Colletotrichum caladii sp. nov. causing anthracnose leaf spot of Caladium × hortulanum (Araceae) in Florida, USA

Caladium (Caladium × hortulanum) is an ornamental plant popular for its variable and colorful foliage. In 2020, plants showing leaf spots and blight, typical of anthracnose, were found in a field trial at the University of Florida's Gulf Coast Research and Education Center (UF/GCREC) in Wimauma, FL, USA. Leaf samples consistently yielded a Colletotrichum-like species with curved conidia and abundant setae production in the acervuli. The internal transcribed spacer (ITS), partial sequences of the glyceraldehyde-3-phosphate dehydrogenase gene (gapdh), actin gene (act), chitin synthase 1 gene (chs-1), beta-tubulin gene (tub2), and histone3 gene (his3) were amplified and sequenced. Blastn searches in the NCBI GenBank database revealed similarities to species of the Colletotrichum truncatum species complex. Phylogenetic analyses using multi-locus sequence data supports a distinct species within this complex, with the closest related species being C. curcumae. Based on morphological and phylogenetic analyses, a new species of Colletotrichum, named C. caladii, is reported. Pathogenicity assays and subsequent isolation confirmed that this species was the causal agent of the disease.

First Report of Leaf Spot Disease on Lonicera japonica Caused by Nigrospora oryzae in China

Lonicera japonica Thunb. is a traditional Chinese medicinal plant, which widely cultivated in China, Japan and Korea. From August to October in 2021 and 2022, severe leaf spots symptoms were observed on L. japonica in medicinal botanical garden of Shandong University of Traditional Chinese Medicine (36°55'89"N, 116°79'91"E), Jinan, Shandong Province, China. The disease incidence was above 80% in the 25 acre cultivation area. Early symptoms were small brown spots on the leaves. Then the number of small spots gradually increased and spread over the entire leaves. The small brown spots seldom merge together to form larger lesions. Leaves with typical symptoms were collected from twenty individual plants, and cut into small 5×5 mm fragments in the junction of infected and healthy tissues. The fragments were sterilized in 75% ethanol for 30 s and 1% NaClO for 60 s, rinsed three times in sterile water, and then placed on potato dextrose agar (PDA). After 3 days of incubation at 25°C, fungal plugs along the edge of the colony were cut and transferred to new PDA for purification. A total number of 23 colonies with similar morphological characteristics were obtained, and three representative strains (Lj14, Lj18 and Lj20) were selected for subsequent study. The colonies grew rapidly on PDA and covered the entire petri dish in 4 days. Colonies had abundant aerial hyphae, initially white, round, later turning gray and black. Conidia were oblate or nearly spherical, single-celled, black, and measured in size from 9.6 to 13.2 μm × 7.9 to 16.1 μm in diameter (n=150) (Figure S1). The observed characteristics were close to those of Nigrospora spp. ( Wang et al. 2017). The genomic DNA was extracted, and PCR amplification of the rDNA internal transcribed spacer (ITS), β-tubulin gene (TUB), and translation elongation factor 1-alpha gene (TEF1) were completed by primers ITS1/ITS4, Bt2a/Bt2b and EF1-728F/EF1-986R (Carbone and Kohn, 1999). Sequences were deposited in GenBank (accession nos. OR936661, OR936662, OR936671 for ITS, OR947626, OR947627, OR947628 for TUB, and OR947629, OR947630, OR947631 for TEF1 sequences, respectively). BLAST analyses of ITS (OR936661), TUB(OR947626) and TEF1 (OR947629) sequences exhibited 100% (487 bp out of 487 bp), 99.48% (380 bp out of 382 bp), and 99.6% (248 bp out of 249 bp) similarity to the sequences of N. oryzae strains KoLRI_053384 (MZ855426), LC2991 (KY019496) and LC7307 (KY019409), respectively. Lj14, Lj18 and Lj20 formed a clade with N. oryzae LC6763 and LC2991 in phylogenetic tree (Figure S2). Based on morphological and molecular evidence, the pathogen was identified as N. oryzae (Berk. &Broome) Petch. To fulfill Koch's postulates, the pathogenicity was tested in vivo experiments. Thirty non-wounded healthy leaves of ten intact plants were inoculated with 10 µl spore suspension (106 spores/ml) of three strains, respectively. As negative control, thirty leaves of ten healthy plants were inoculated with sterile water. The inoculated plants were placed at 28°C in the growth chamber with high relative humidity. The pathogenicity tests were repeated three times. Distinct symptoms similar to that of natural conditions were observed on the leaves of inoculated plants after 4 to 7 days. The strain was reisolated from the lesions and identified as N. oryzae by morphological features and ITS sequence. The pathogen has been reported to cause leaf spot disease on tobacco (Wang et al. 2022) and asiatic dayflower (Qiu et al. 2022). To our knowledge, this is the first report of leaf spot caused by N. oryzae on Lonicera japonica in China. The research will be helpful for leaf spot disease control.

First Report of White Mold Caused by Sclerotinia sclerotiorum on Hymenocallis glauca in Mexico

In Mexico, there are 29 native species of the genus Hymenocallis, where H. glauca is one of the most cultivated bulbous plants. It holds economic importance as it is commercialized as a potted plant and cut flower (Leszczyñska and Borys, 2001). In October 2023, field sampling was conducted in the Research Center in Horticulture and Native Plants (18°55'55" N, 98°24'02.8"W) of UPAEP University. H. glauca diseased plants were found in an area of 0.4 ha, with an incidence of 35% and an estimated severity of 45% on infected plants in vegetative stage. The symptoms included chlorosis of foliage, necrosis at the base of the stem, and soft rot with abundant white to gray mycelium and abundant production of black, irregular sclerotia of approximately 3.5 mm diameter. Finally, the plants wilted and died. The fungus was isolated from 40 symptomatic plants. Sclerotia were collected, disinfested with 3% NaOCl for one minute, rinsed with sterile distilled water (SDW), and plated on Petri dishes containing potato dextrose agar (PDA) with sterile forceps. Subsequently, a sterile dissecting needle was used to place fragments of mycelium directly on Petri dishes with PDA. Plates were incubated at 23 °C in dark for 7 days. One isolate was obtained from each diseased plant by the hyphal-tip method (20 isolates from sclerotia and 20 from mycelium). After 7 days, colonies had fast-growing, dense, and cottony-white aerial mycelium forming irregular sclerotia of 3.57 ± 0.59 mm (mean ± standard deviation, n=100). In each Petri dish there were produced 21.5 ± 7.9 sclerotia (mean ± standard deviation, n=40), after 11 days; these were initially white and gradually turned black. The isolates were tentatively identified as Sclerotinia sclerotiorum based on morphological characteristics (Saharan and Mehta 2008). Two representative isolates were chosen for molecular identification and genomic DNA was extracted by the CTAB protocol. The ITS region and the glyceraldehyde 3-phosphate dehydrogenase (G3PDH) gene were amplified and sequenced (Staats et al. 2005; White et al. 1990). The sequences of a representative isolate (SsHg3) were deposited in GenBank (ITS- PP094578; G3PDH- PP101843). BLAST analysis of the partial sequences ITS (519 bp), and G3PDH (950 bp) showed 100% similarity to S. sclerotiorum isolates (GenBank: MG249967, MW082601). Pathogenicity was confirmed by inoculating 30 H. glauca plants in vegetative stage grown in pots with sterile soil. Ten sclerotia were deposited at the base of the stem, 10 mm below the soil surface. As control treatment, SDW was applied to 10 plants. The plants were placed in a greenhouse at 23 °C and 90% relative humidity. After 17 days, all inoculated plants displayed symptoms similar to those observed in the field, while no symptoms were observed on the controls. The fungus was re-isolated from the inoculated plants as described above, fulfilling Koch's postulates. The pathogenicity tests were repeated three times. S. sclerotiorum has been reported causing white mold on other bulbous plants, like fennel (Foeniculum vulgare) in Korea (Choi et al. 2015). To our knowledge, this is the first report of S. sclerotiorum causing white mold on H. glauca in Mexico. Information about diseases affecting this plant is very limited, so this research is essential for developing integrated management strategies and preventing spread to other production areas.

Phytophthora pseudocryptogea Is Associated with Root and Crown Rot of Nursery-Grown Common Sage in Hungary

In October 2009, necrotic bark lesions at the root collar and lower stem associated with root rot, reduced growth, and wilting were observed on container-grown 2-year-old common sage (Salvia officinalis L. 'Icterina') in two ornamental nurseries in Somogy and Zala counties in Hungary. The disease occurred at a frequency of 15-20% (100 to 150 symptomatic plants in each nursery). A P. cryptogea-like species was isolated consistently from necrotic root collars of many plants on carrot (CA) PARPB agar. Six isolates from the nursery in Zala county and three isolates from the nursery in Somogy county were deposited in the culture collection of Plant Protection Institute (Budapest, Hungary). All developed slightly petaloid colonies on CA agar. Chlamydospores and gametangia were not present in single and dual culture combinations of isolates. Radial colony growth was the fastest at 25°C (6.8 to 7.4 mm/day) and no growth occurred above 34°C. On mycelial discs floating in nonsterile stream water, persistent, nonpapillate, mostly ovoid to obpyriform sporangia (37.4±3.5 to 47.8±4.6 μm long and 22.3±2.6 to 29.2±3.7 μm wide) and hyphal swellings were produced abundantly. Pathogenicity of one selected isolate from each nursery was tested on 3-month-old seedlings of S. officinalis 'Icterina' in 2010. Isolates were grown for 4 weeks at 20°C on autoclaved millet grains moistened with CA broth. Infested and uninfested grains were mixed with autoclaved soil (30 cm3 grain/liter), and the mixes were used as potting media for transplanting five treated and five control plants per isolate, respectively. Plants were kept in a growth room (20-25°C, 16/8 h dark/light). Pots were flooded for 24 hours on the 1st day and every 2 weeks. All and only treated plants showed symptoms of wilt associated with basal stem and root necrosis within three weeks. The trial was repeated with the same result. The pathogen could be reisolated only from the treated plants. Identity of isolates from nurseries and inoculated plants was confirmed recently by amplification and sequence analysis of the rDNA internal transcribed spacers (ITS) and gene regions of cytochrome c oxidase subunit I (coxI) and β-tubulin (tub) according to Jung et al. (2017). BLASTn searches showed 100% identity and only 97.3-99.0% similarity to the corresponding sequences of authenthic P. pseudocryptogea and P. cryptogea strains, respectively (e.g., GenBank accession nos. KP288336-KP288342, KP288370-KP288372, KP288386-KP288392, MN872725, MN872776). Sequences of the 9 field isolates were deposited in GenBank under accession nos. OR771701-OR771709 (ITS), OR787508-OR787516 (coxI) and OR787517-OR787525 (tub). P. pseudocryptogea was delineated from P. cryptogea sensu lato (Safaiefarahani et al. 2015), which has been reported from S. officinalis in the United States (Koike 1997), and S. leucantha (Cacciola et al. 2002) and S. officinalis (Garibaldi et al. 2015) in Italy. The known natural hosts of P. pseudocryptogea includes plant species in families other than Lamiaceae (cf. Aloi et al. 2023), but it was pathogenic on the lamiaceous Plectranthus scutellarioides in artificial inoculations (Christova 2020). The pathogen is present in European nurseries (Antonelli et al. 2023). This is the first report of P. pseudocryptogea on S. officinalis in Hungary. The causal agent threatens the production of sages and other ornamentals, and its spread in Hungary should be prevented by proper disease management and phytosanitary actions.

Podosphaera xanthii Causing Powdery Mildew on Salvia farinacea in Central China

Salvia farinacea, commonly referred as mealycup sage, is a perennial herbaceous plant belonging to the Salvia genus of the Lamiaceae family. It originates from the Mediterranean region, North America, and Europe and is globally cultivated due to its appealing and captivating flowers. Moreover, mealycup sage is utilized as traditional Chinese medicinal plant for treatment of cardiovascular diseases (Li et al. 2018). In October 2023, powdery mildew-like symptoms were observed on Salvia farinacea plants cultivated in a garden located in Xinxiang City, Henan Province, China (113.93, 35.29). The leaves were covered with white and thin masses of mycelia, conidiophores and conidia of the fungus. About 100 plants were checked and 90 % were infected. There were a large number of white colonies with irregular or continuous round lesions on the adaxial and abaxial surfaces of the leaves, covering approximately 80% of the leaf area. The slightly or straight curved conidiophores (n = 30) were 46 to 145× 8 to 11 μm in size and consisted of foot cells, shorter cells and conidia. The ellipsoidal to oval conidia (n = 30), containing fibrosin bodies, were 24 to 35 × 12 to 19 μm in size and had a length/width ratio of 1.8 to 2.1. No chasmothecia were observed on leaves. These morphological features were consistent with those of Podosphaera xanthii (Braun and Cook 2012). Following the previously described method (White et al. 1990; Bradshaw et al. 2022; Zhu et al. 2022a), the sequences of ITS and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) regions were amplified with specific primers ITS1/ITS4 (ITS1 5'-TCCGTAGGTGAACCTGCGG-3' ; ITS4 5'-TCCTCCGCTTATTGATATGC-3') and PMGAPDH1/PMGAPDH3R (PMGAPDH1 5'-GGAATGGCTATGCGTGTACC-3'; PMGAPDH3R 5'-CCCCATTCGTTGTCGTACCATG-3'), and the resulting sequences were uploaded in GenBank (Accession No. OR761885 and PP236082, respectively). BLASTn analysis showed that the sequence shared 560/565 (99%) and 272/272 (100%) homology with P. xanthii (MW301281) on Impatiens balsamina (Zhu et al. 2022b) and with P. xanthii (ON075658) on Cucumis melo (Bradshaw et al. 2022), respectively. The phylogenetic analysis clearly illustrated that the collected isolate of P. xanthii clustered in the same clade. The pathogenicity was tested according to the method previously described (Zhu et al. 2021). The fungus was inoculated onto the leaf surfaces of three healthy plants by blowing conidia from infected leaves with pressurized air. Non-inoculated plants were treated as control. Both the control and inoculated plants were separately placed in growth chambers under 60% humidity; light/dark, 16 h/8 h; and a temperature of 18°C. After a period of 12-15 days, the leaves of the inoculated plants exhibited signs of powdery mildew, whereas the control group remained unaffected. Therefore, the fungal pathogen was identified and confirmed as P. xanthii (isolate PXSF202310). Previously, P. xanthii was reported on Impatiens balsamina and S. farinacea from China and Korea (Zhu et al. 2021; Choi et al. 2022). As far as we know, this is the first documentation of P. xanthii on S. farinacea in central China. The presence of P. xanthii can lead to a deterioration in plant health and stunted growth, thereby negatively impacting both the decorative and medicinal value of S. farinacea. The recognition of P. xanthii on S. farinacea enhances our comprehension of this pathogen hosts and provides fundamental information for forthcoming disease control studies.

Hematological and plasma biochemical profile of two species of freshwater stingrays from the Amazon

The evaluation of hematological and plasma biochemical parameters and the subsequent establishment of reference intervals facilitate the diagnosis of the health status of animals. This work aimed to determine the blood parameters of wild specimens of the stingrays Potamotrygon motoro and Potamotrygon orbignyi from the lower Solimões River region, Amazonas, Brazil. One hundred forty-one stingrays were captured, 92 specimens of P. motoro and 49 of P. orbignyi, of both sexes and at different stages of development. No effect of sex was observed on the blood parameters of juvenile animals for both species. P. motoro neonates presented a distinct hematological and biochemical profile, with significantly lower hematocrit values, hemoglobina, number of erythrocytes, mean corpuscular hemoglobin concentration, monocytes, plasma glucose, total proteins, albumin, and globulin. On the other hand, total cholesterol and urea levels were significantly higher in this same group compared to juveniles of the same species. Comparison between species revealed lower values of triglycerides and total cholesterol in P. orbignyi of both sexes. The results obtained are pioneering for these Amazonian species in white water environments and will serve as a basis for evaluating the health status of wild stingrays. Thus, from the analysis of the blood of the P. motoro and P. orbignyi stingrays, it was possible to observe good health conditions.

First Report of Agroathelia rolfsii Causing Southern Blight on Lippia (Phyla canescens) in Guangzhou, China

Lippia (Phyla canescens) is a fast-growing, mat-forming, and prostrate perennial plant well adapted to infertile, high-saline, and drought environments (Leigh, et al. 2004). It arrived in China from Japan as a flowering ground cover in 2001 (Cai, et al. 2004). In June 2022, southern blight appeared in our nursery of the Floriculture Research Institute of Guangdong Academy of Agricultural Sciences. High temperature and damp environment are major factors for this disease. The symptoms of top-layer plants were not easily detected, but they were slightly yellowed. A yellowish-brown water-soak lesion appeared on the stems and lowest leaves exposed to soil. White mycelium appeared in the middle stage. Finally, the surface plants showed water-soak decay, and a mass of beige to black-brown rapeseed-shaped sclerotia appeared on the residue and surrounding soil; these plants died. Sclerotia and mycelia were collected from disease tissue, and after surface sterilization, sclerotia was cultured on potato dextrose agar (PDA) at 28±2°C in an incubator without light. Eight fungal isolates with similar colony morphologies were consistently isolated by purifying from different sampling areas. The isolates exhibited obvious septa and a clamp connection structure within the white mycelium. The average growth rate was 26.86±0.06 mm/day. Numerous white granular sclerotia were produced on the mycelium 6 days later. The sclerotia with a diameter of 1.24±0.07mm (n=189) gradually changed from diage to yellow to brown. A typical strain B1 was selected for further identification, targeting its 18S rRNA and LSU rRNA sequences (Yang, et al. 2011; Xue, et al. 2019). Its 18S rRNA sequence (GenBank Accession No. OR517233, 1626 bp) is 99.63% and 99.57% identical to Athelia rolfsii (AY665774, 1179bp; KC670714, 1775bp; JF819726, 1781bp). Its LSU rRNA sequence (OR539570, 757 bp) is 99.87% identical to Agroathelia rolfsii (OR526537, 904 bp). For Athelia rolfsii, a synonym of Agroathelia rolfsii, by combining the morphological characteristics and molecular identification, the isolate pathogen B1 was confirmed to be Agroathelia rolfsii (the teleomorph of Sclerotium rolfsii). To fullfill Koch's postulates, we inoculated the mycelial plugs to healthy lippia stems and leaves which has grown for one year, with PDA plugs free of mycelium as the control. All the plants were kept in a greenhouse at 28±2°C with a 14-h photoperiod and 80% relative humidity. Each treatment was repeated thrice and vaccinated with 6 points. At 7 d following inoculation, all plants inoculated with B1 showed typical symptoms, but the control group was asymptomatic, and sclerotia appeared 17d after inoculation. Using the same protocol mentioned above, pathogenic fungal was reisolated only from treated groups, but not from the control group. Chose three of the pathogens for 18S rRNA and LSU rRNA sequencing, the results showed 100% identity to B1, the same as its microstructure. There are few reports about the disease on P. canescens. Sosa (2007) investigated the pathogens on P. canescens in Argentina, 16 fungi were found but no A. rolfsii. Sclerotium rolfsii were identified on P. nodiflora or P. lanceolata (Michaux) Greene in America (Farr, et al. 1989). To our knowledge, this is the first report in China. Because this pathogen has wide-ranging hosts and causes serious damage, the results from this study will offer guidance for the prevention and treatment of this disease.

First Report of Pectobacterium polaris Causing Soft Rot on Broccoli in China

In April 2023, soft rot symptoms were observed in broccoli (Brassica oleracea L. var. italica) commercial fields in Songming County, Yunnan province, China (103°12'E, 25°31'N). The disease incidence in these fields (6 ha in size) was high, exceeding 50%, and it caused significant yield loss. The affected plants displayed characteristic symptoms, with the roots and stems of broccoli becoming soft, yellowish-brown, rotten, and emitting a foul odor. To identify the causal agent, soft rot symptomatic stems were surface sterilized by dipping them in 75% ethanol for 30 seconds, followed by three successive rinses with sterile distilled water. Tissue specimens were then plated onto nutrient agar (NA) plates and incubated at 28°C for 24 hours. (Wang et al. 2022). Three representative bacterial isolates HYC22041801-HYC22041803 from broccoli were selected for further analysis. The colonies on NA plates appeared as white, small, round, and translucent with smooth edges. Physiological and biochemical tests were performed, along with 96 phenotypic screenings using the BIOLOG GENIII microplate system (Biolog, Hayward, CA, USA). Three isolates were negative for D-arabitol, maltose, and sorbitol, but were positive for cellobiose, α-D-glucose, sucrose, glycerol and gentiobiose tests, which are consistent with the reported type strain P. polaris NIBIO1006T (Chen et al. 2021). Total genomic DNA was extracted from three bacterial isolates using the QIAamp DNA Mini Kit (QIAGEN, USA). The 16S rRNA region and nine housekeeping genes (gapA, icdA, mdh, mtlD, pel, pgi, pmrA, proA and rpoS) were amplified with universal primers 27F/1492R (Monciardini et al., 2006) and designed specific primers (Xie et al., 2018), respectively. All amplicons were sequenced and deposited in GenBank with accession numbers ON723841-ON723843 and ON723846-ON723872. The BLASTn analysis of the 16S rRNA amplicons confirmed that the isolates HYC22041801-HYC22041803 belonged to the genus Pectobacterium. Phylogenetic trees based on 16S rRNA gene sequences and multilocus sequence analysis of other nine housekeeping genes of the three isolates were constructed and the results revealed that three isolates clustered with P. polaris type strain NIBIO1006T, which was previously isolated from potato (Dees et al., 2017). To confirm the pathogenicity, nine broccoli seedlings were stab inoculated with a bacterial suspension (108 CFU·ml-1), while sterile distilled liquid LB medium was used as a negative control. The seedlings were kept at 80% relative humidity and 28°C in a growth chamber. Three trials were conducted per isolate (HYC22041801-HYC22041803). After 3 days, the inoculated petioles showed soft rot symptoms similar to those observed initially in the field, while control plants remained asymptomatic. All three isolates were re-isolated successfully from symptomatic tissues to complete Koch's postulates. P. polaris has been previously reported as the causative agent of blackleg in potato in several countries, including Norway, Poland, Russia, and China (Handique et al. 2022; Wang et al. 2022). Additionally, it was reported to cause soft rot in Chinese cabbage in China (Chen et al. 2021). However, this is the first report of P. polaris causing soft rot disease in broccoli in China. This discovery is of great importance for vegetable growers because this bacterium is well established on Cruciferous vegetables in the local area, and effective measures are needed to manage this disease.

First Report of Powdery Mildew Caused by Podosphaera xanthii on Youngia japonica subsp. elstonii in Hainan Province, China

Youngia japonica (L.) DC. is a polymorphic annual herb of the Asteraceae family. Although this plant originated in Asia, it is now world-widely distributed. In China, Y. japonica is used for edible or folk medicine to treat viral infections and various kinds of inflammation (Yu et al. 2021). As a traditional Chinese medicinal herb, Y. japonica used for the treatment of inflammatory diseases, such as angina, leucorrhea, mastitis, conjunctivitis, and rheumatoid arthritis (Chen et al. 2006). During the spring of 2023, powdery mildew symptoms were observed on 60% of Y. japonica subsp. elstonii plants in a greenhouse on the Hainan Medical University campus (19° 58' 53″ N; 110° 19' 47″ E) in Haikou, Hainan Province, China. Powdery mildew colonies covered the leaf surfaces and stems of affected plants, causing discoloration and defoliation. Mycelia were superficial and hyphal appressoria were nipple-shaped. Conidiophores (n =30) were unbranched, cylindrical, 99 to 166 × 11 to 16 µm, and produced three to five immature conidia in chains with a crenate outline. Foot cells (n =30) were cylindrical, straight or sometimes curved at the base, and 35 to 61 µm long. Conidia (n =100) were ellipsoid-ovoid to doliiform, 21 to 40 ×13 to 21 µm (length/width ratio = 1.4 to 2.3), with well-developed fibrosin bodies, and produced germ tubes from the lateral position. Based on these morphological characteristics, the pathogen was provisionally identified as Podosphaera xanthii (Braun and Cook 2012). The teleomorph was not observed. A specimen was deposited in the Hainan Medical University Plant Pathology Herbarium as HMYJ-23. To confirm the genus identification and ascertain a putative species, genomic DNA was extracted from mycelium, conidiophores, and conidia using a fungal DNA kit (Omega Bio-Tek, USA). The rDNA internal transcribed spacer (ITS) region was amplified with primers ITS1/ITS4 (White et al. 1990) and sequenced directly. The resulting 575-bp sequence was deposited in GenBank (accession no. OR229712). A BLASTn search in GenBank of this sequence showed 99% similarity with the ITS sequences of P. xanthii isolates from China (MT260063, OP765400, MW422608, and MT739423), Thailand (LC270778, LC270779, and LC270780), and Argentina (AB525914). Additionally, the 613-bp 28S rDNA region was amplified using the primer pairs NL1 and NL4 (O'Donnell 1993; accession no. OR240257). This region shared 100% similarity with P. xanthii isolates (MK357436, LC371333, LC270780, OP765401, and AB936277) as well. To confirm pathogenicity, five healthy potted plants of Y. japonica subsp. elstonii were inoculated by gently pressing a powdery mildew-infected leaf onto the young leaves. Five non-inoculated plants served as controls. All plants were maintained in a greenhouse at 24 to 30°C, 70% relative humidity, with a 16-h photoperiod. After 7 days, inoculated leaves showed powdery mildew symptoms whereas no symptoms were observed on control plants. The fungal colonies observed on inoculated plants were morphologically identical to those found on the originally infected leaves collected from Hainan Province. Based on the morphological characteristics and molecular identification, the fungus was identified as P. xanthii. To our knowledge, this is the first record of P. xanthii infecting Y. japonica subsp. elstonii in Hainan province, China. We are concerned that the pathogen could become a threat to the widespread planting of Y. japonica subsp. elstonii in the future.

First Report of Powdery Mildew Caused by Podosphaera xanthii on Sphagneticola trilobata in Hainan Province, China

Sphagneticola trilobata (L.) Pruski is a perennial creeping herb of the Asteraceae family, which is native to South America. It was introduced into Southern China as a groundcover in the 1970s (Zhang et al. 2023). Now it is mainly used for folk medicine to treat various kinds of inflammatory, incuding joint pain, rheumatic diseases, arthritis, in addition to treating persistent wounds, ulcers, and edemas (Gonçalves et al. 2022). In February and November 2023, powdery mildew symptoms were observed on 60% of S. trilobata plants on the Hainan Medical University campus (19° 58' 53″ N; 110° 19' 47″ E) in Haikou, Hainan Province, China. Powdery mildew colonies covered the leaf surfaces and stems of affected plants, causing discoloration and defoliation. Mycelia were superficial and hyphal appressoria were nipple-shaped. Conidiophores (n =30) were unbranched, cylindrical, 74 to 161 × 10 to 14 µm, and produced three to five immature conidia in chains with a crenate outline. Foot cells (n =30) were cylindrical, straight or sometimes curved at the base, and 27 to 56 µm long. Conidia (n =100) were ellipsoid-ovoid to doliiform, 17 to 30 ×14 to 28 µm (length/width ratio = 1.1 to 1.9), with well-developed fibrosin bodies, and produced germ tubes from the lateral position. Based on these morphological characteristics, the pathogen was provisionally identified as Podosphaera xanthii (Braun and Cook 2012). The teleomorph was not observed. A specimen was deposited in the Hainan Medical University Plant Pathology Herbarium as HMST-23. To confirm the genus identification and ascertain a putative species, genomic DNA was extracted from mycelium, conidiophores, and conidia using a fungal DNA kit (Omega Bio-Tek, USA). The rDNA internal transcribed spacer (ITS) region was amplified with primers ITS1/ITS4 (White et al. 1990) and sequenced directly. The resulting 577-bp sequence was deposited in GenBank (accession no. OR784549). A BLASTn search in GenBank of this sequence showed 100% similarity with the ITS sequences of P. xanthii isolates from China (MT260063, MN203658, OP765400, and MT739423), Thailand (LC270780), and Vietnam (KM260731, KM260730, and KR779870). Additionally, the 28S rDNA region was amplified using the primer pairs NL1 and NL4 (O´Donnell 1993; accession no. OR784550). This region shared 100% similarity with P. xanthii isolates (LC371334, LC270782, AB936277, and OP765401) as well. Powdery mildew from Hainan sample belonged to the P. xanthii group with strong bootstrap values support 99% in maximum likelihood phylogenetic tree based on ITS and 28S gene sequences. To confirm pathogenicity, five healthy potted plants of S. trilobata were inoculated by gently pressing a powdery mildew-infected leaf onto 15 young leaves. Five non-inoculated plants served as controls. All plants were maintained in a greenhouse at 24 to 30°C, 70% relative humidity, with a 16-h photoperiod. After 7 days, inoculated leaves showed powdery mildew symptoms whereas no symptoms were observed on control plants. The fungal colonies observed on inoculated plants were morphologically identical to those found on the originally infected leaves collected from Hainan Province. Based on the morphological characteristics and molecular identification, the fungus was identified as P. xanthii. In different countries and regions, P. xanthii has been previously reported on S. trilobata in Taiwan (Yeh et al. 2021). To our knowledge, this is the first record of P. xanthii infecting S. trilobata in Hainan Province, China. S. trilobata is often planted as an ornamental plant on both sides of the road, and we are concerned that it may serve as a new host, spreading this pathogen to other economic crops.

Molecular-Phylogenetic Characterization of Xanthomonas hortorum pv. pelargonii Strains Causing Leaf Spot of Geraniums in Iran

Bacterial blight and leaf spot of geraniums is a destructive disease of cultivated Pelargonium species around the world. During 2020-2021, surveys were conducted in seven geranium-growing provinces of Iran to monitor the status of bacterial blight and leaf spot disease. The disease was observed in six surveyed provinces varying in the extent of occurrence and severity. Twenty-two Gram-negative pale-yellow bacterial strains resembling members of Xanthomonas were isolated from symptomatic leaves and stems. Pathogenicity and host range assays showed that the bacterial strains were pathogenic on Pelargonium grandiflorum, P. graveolens, P. peltatum, and P. zonale. All strains were positive for PCR test using the primer pair XcpM1/XcpM2 which is specific for Xanthomonas hortorum pv. pelargonii. Phylogenetic analysis using the sequences of gyrB and lepA genes showed that the 22 strains clustered in a clade among the sequences of X. hortorum pv. pelargonii strains retrieved from the GenBank, while distinct from the other pathovars of X. hortorum. BOX-PCR-based fingerprinting using BOX-A1R primer revealed that the strains isolated in this study were grouped into two clusters while no distinct correlation was observed between the host/area of isolation and BOX-PCR fingerprinting. None of the strains obtained in this study nor reference strain of the pathogen did produce bacteriocin against each other. Results obtained in this study shed light on the geographic distribution, taxonomic status and host range of the bacterial blight and leaf spot pathogen of geraniums in Iran, paving the path of further research on disease management.

First Report of Powdery Mildew Caused by Podosphaera xanthii on Acalypha indica in China

Acalypha indica L. is an annual erect herb of the Euphorbiaceae family. This plant is found widely in the tropics and parts of Africa and Asia (Chakraborty et al. 2023). In China, A. indica is a vegetable and also used as a folk medicine due to its antipyretic and hemostatic, antibacterial and anti-inflammatory properties. In February 2022 and 2023, powdery mildew symptoms were observed on 70% of A. indica plants on the Hainan Medical University campus (19° 58' 53″ N; 110° 19' 47″ E) in Haikou, Hainan Province, China. Powdery mildew colonies covered the leaf surfaces and stems of affected plants, causing discoloration and defoliation. Mycelia were superficial and hyphal appressoria were nipple-shaped. Conidiophores (n =30) were unbranched, cylindrical, 66 to 150 × 10 to 15 µm, and produced three to five immature conidia in chains with a crenate outline. Foot cells (n =30) were cylindrical, straight or sometimes curved at the base, and 31 to 59 µm long. Conidia (n =100) were ellipsoid-ovoid to doliiform, 20 to 33 ×12 to 20 µm (length/width ratio = 1.3 to 2.4), with well-developed fibrosin bodies, and produced germ tubes from the lateral position. Based on these morphological characteristics, the pathogen was provisionally identified as Podosphaera xanthii (Braun and Cook 2012). The teleomorph was not observed. A specimen was deposited in the Hainan Medical University Plant Pathology Herbarium as HMAI-23. To confirm the genus identification and ascertain a putative species, genomic DNA was extracted from mycelium, conidiophores, and conidia using a fungal DNA kit (Omega Bio-Tek, USA). The rDNA internal transcribed spacer (ITS) region was amplified with primers ITS1/ITS4 (White et al. 1990) and sequenced directly. The resulting 575-bp sequence was deposited in GenBank (accession no. OR775733). A BLASTn search in GenBank of this sequence showed 99% similarity with the ITS sequences of P. xanthii on plants of Fabaceae, Malvaceae and Cucurbitaceae family from China (MH143485, MT242593, MK439611 and MH143483), Thailand (LC270779 and LC270778), Korea (MG754404), Vietnam (KM260704), and Puerto Rico (OP882310). Additionally, the 28S rDNA region was amplified using the primer pairs NL1 and NL4 (O´Donnell 1993; accession no. OR784547). This region shared 99% similarity with P. xanthii isolates (LC371333, LC270780, AB936277, and OP765401) as well. To confirm pathogenicity, five healthy potted plants of A. indica were inoculated by gently pressing a powdery mildew-infected leaf onto 15 young leaves. Five non-inoculated plants served as controls. All plants were maintained in a greenhouse at 24 to 30°C, 70% relative humidity, with a 16-h photoperiod. After 7 days, inoculated leaves showed powdery mildew symptoms whereas no symptoms were observed on control plants. The fungal colonies observed on inoculated plants were morphologically identical to those found on the originally infected leaves collected from Hainan Province. Based on the morphological characteristics and molecular identification, the fungus was identified as P. xanthii. In different countries and regions, P. xanthii has been previously reported on A. indica from Sudan and India (Amano 1986). To our knowledge, this is the first record of P. xanthii infecting A. indica in China. We are concerned that the pathogen could become a threat to the widespread planting of A. indica in the future.

First report of leaf blight caused by Stemphylium lycopersici on Salvia splendens in China

Salvia splendens is a popular ornamental plant in China with extensive potentials, including value in traditional Chinese medicine and in environmental restoration function (Li et al. 2008). In September 2019, leaf blight disease was observed on road side plants of S. splendens in Bayi park, Nanchang city, Jiangxi province, China. The typical symptoms appeared as irregular necrotic spots or leaf blight, accompanied by extensive scorch necrosis or ultimately defoliation. Small segments cut from diseased leaves were surface sterilized in a 2% sodium hypochlorite solution for 2 min and rinsed three times with sterile distilled water. Then, the samples were placed on potato dextrose agar (PDA) plates incubated at 25°C in darkness. Pure cultures were obtained by the hyphal tip method. Morphologically, all 11 colonies were identical to each other on PDA. Two strains, YZU 191468 and YZU 191481, were selected for further study and deposited in the Fungal Herbarium of Yangtze University (YZU), Jingzhou, Hubei, China. The 7-day-old colonies were circular, 53 to 56 mm in diameter, and consisted of white mycelium with a buff margin, and were cinnamon colored in the center of the reverse side. To examine conidial morphology, the mycelium was transferred onto potato carrot agar (PCA) and incubated at 23°C with a period of 8 h light/16 h dark for 7 days. Conidia were normally solitary or two in a chain, ellipsoid or long ellipsoid, beakless, 10 to 23×30 to 60 µm in size (n=50). Based on morphology, the isolates were consistent with Stemphylium lycopersici (Yamamoto 1960). To confirm the identification, genomic DNA was extracted from both isolates and used to amplify the internal transcribed spacer rDNA region (ITS), glyceraldehydes-3-phosphate dehydrogenase (GAPDH) and calmodulin (CAL) genes with primer pairs ITS5/ITS4, gpd1/gpd2, and CALDF1/CALDR2, respectively (Woudenberg et al. 2017). Sequences were deposited in GenBank with accession numbers OP564983 and OP564984 (ITS), OP892529 and OP892530 (GAPDH), OP584970 and OP584971 (CAL). A neighbor-joining tree was constructed with Mega 7.0 based on the combined dataset with 1,000 bootstrap replicates. The resulting phylogenetic tree showed that the strains from S. splendens clustered with S. lycopersici (CBS 122639 and CBS 124980) supported with 100% bootstrap values. The molecular analyses confirmed that the species causing leaf blight symptoms was S. lycopersici. To test pathogenicity, healthy leaves of S. splendens were surface sterilized and inoculated by mycelium blocks (6 mm in diameter) and spore suspension (1×106 spore/mL) of representative strains YZU 191468 and YZU 191481, respectively. Controls were inoculated with blocks of PDA and sterile water. Each strain was inoculated on three leaves of a plant. One clean plant was used as control. The test was replicated three times. After inoculation, the plants were covered with plastic bags and incubated in a greenhouse (25℃, 80 % relative humidity, 8 h light/16 h dark). After 5 days, the inoculated leaves exhibited dark brown spots with white mycelium, followed by withering of necrotic tissues. There were no symptoms observed on the controls. The fungal isolates inoculated leaves had the same morphological characteristics as the strains used for inoculation. S. lycopersici has been found on eggplant and Zinnia elegans in China (He et al. 2019; Yang et al. 2017). To the best of our knowledge, this is the first report of S. lycopersici causing leaf blight on S. splendens in China. This finding offers a new reference for the management and control of S. splendens leaf diseases in China.

First Report of Anthracnose on Euonymus japonicus Thunb. Caused by a Provisionally Novel Species of Colletotrichum in the Magnum Complex in South Korea

Euonymus japonicus Thunb., also known as the evergreen spindle tree, is an evergreen tree, which is widely planted as a hedge plant along streets in South Korea. In April 2022, severe anthracnose symptoms were observed on the leaves of this tree in Jangsu in the Jeonbuk Province of the country (35°43'49.44″N, 127°34'53.7″E). About 80% of the leaves of each affected tree within a 0.03-ha area showed incidence of the disease on approximately 30 trees were planted along the roadside (~30 m). These symptoms typically included circular or irregularly shaped whitish-gray lesions with a diameter of 2.0 to 3.0 cm. In cases where some leaves were severely affected, larger blotches formed. To isolate the pathogen, about ten leaves showing anthracnose symptoms on each tree were randomly selected and brought to the laboratory. Fungal isolations were made from acervuli filled with conidial masses on infected evergreen tissues, followed by plating onto 2% potato dextrose agar (PDA) as well as incubated at 25℃. On the PDA, colonies were circular, raised, green-grey or dark grey, and had a distinct white margin. The conidia were single-celled, transparent, cylindrical with rounded ends, had smooth walls, with a length ranging from 12 μm to 16.7 μm and a width raging from 4 μm to 6.5 μm (av. = 14.1 X 5.0 μm, n=40). Of those that were successfully recovered with approximately 90% frequency, two monoconidial isolates were deposited to the culture collection at Chungnam National University in South Korea (Accession number: CDH059-060). To ensure the identity of the fungus, genomic DNAs were extracted from the selected isolates, CDH059-060, and were sequenced. This was achieved based on partial sequences of the internal transcribed spacer (ITS), actin and beta-tubulin (TUB2) gene regions which were amplified using ITS1F / ITS4 (Gardes and Bruns 1993; White et al. 1990), ACT-512F / ACT-783R (Carbone and Kohn 1999), and T1 / Bt2b (O'Donnell and Cigelnik 1997; Glass and Donaldson 1995) primer pairs, respectively. The resulting sequences were deposited to GenBank (OR984424-425) for ITS, (OR996289-290) for actin, and (OR996291-292) for TUB2. For a phylogenetic analysis, sequences from different gene regions (ITS, actin and TUB2) retrieved from GenBank were aligned, concatenated, and analyzed as a single dataset based on a maximum likelihood analysis. The phylogenetic result revealed that the fungus isolated in this study was positioned in a clearly distinct lineage, provisionally representing an undetermined species of Colletotrichum, which is most closely related to Colletotrichum liaoningense (Y.Z. Diao, C. Zhang, L. Cai & X.L. Liu, CGMCC3.17616 (KP890104 for ITS, KP890097 for actin, and KP890111 for TUB, Diao et al. 2017). Sequence comparisons revealed that this pathogen differed from C. liaoningense at 20 of 494 characters (∼4.0%) in the ITS and 2 of 251 (∼1.0%) in the actin sequences. For pathogenicity tests, three seedlings of E. japonicus were used. The leaves for each tree were treated with 10 ml of a conidial suspension by spraying (1x10⁶ conidia ml-1 of the isolate, CDH059), while the three seedlings were treated with distilled water as control. After sprayed, the treated areas were sealed with plastic bags for a day to maintain humidity. Anthracnose symptoms identical to those observed in the field appeared seven days after inoculations, while no symptoms were observed in the control. Re-isolations were successfully achieved from the treatments, fulfilling Koch's postulates. Anthracnose associated with the provisionally novel species of Colletotrichum sp. on E. japonicus has not been recorded elsewhere, and in this regard, this is the first report of anthracnose caused by Colletotrichum sp. on E. japonicus in Korea. To effectively control the disease, more attention should be paid to the host range of the pathogen and other regions where the disease caused by the pathogen might occur in the country.

First report of Pseudomonas cichorii causing bacterial leaf blight of pocketbook plant (Calceolaria hybrida) in Taiwan

Pocketbook plants (Calceolaria spp.) are flowering ornamentals often grown as potted plants (Poesch 1937). In December 2022, leaf blight symptoms were observed on 2-mo-old plants of C. hybrida F1 'Dainty'. The disease was found in a nursery in Ren'ai Township, Nantou, and about 20% of the plants exhibited symptoms. Symptomatic plants had brown or gray necrotic lesions of different sizes and shapes, mostly around leaf margins. Lower leaf wilting was also observed (Fig. S1, A and B). Three plants were sampled. Leaf lesions were surface-disinfected with 75% ethanol and cut into smaller pieces in 10 mM MgCl2. After observing bacterial streaming under a microscope, the bacteria were streaked onto nutrient agar (NA). Following 2 days at 28°C, a type of round, creamy white colony predominated on all the plates. Three strains (Calc-A, Calc-B, and Calc-C) were obtained, one from each plant. The strains produced fluorescent pigments on King's B medium and were tested Gram-negative. The strains were characterized with the LOPAT scheme (Schaad et al. 2001). They did not exhibit activities of pectic enzymes, arginine dihydrolase and levan sucrase, but produced oxidase and induced the hypersensitive response in tobacco. DNA was extracted from the strains for PCR amplification of the 16S rDNA with primer pair 27f/1492r as described by Lane (1991). The 16S rDNA sequences were compared with entries in the GenBank database. The sequences obtained (GenBank accession no. OR824302) matched that of Pseudomonas cichorii MAFF 301158 (accession no. AB724288; 1,403/1,403 bp) and were 99% identical to that of DSM 50259T (accession no. CP074349; 1,391/1,405 bp). The strains were also tested with the species-specific primers hrp1a and hrp2a (Cottyn et al. 2011). The amplicons were sequenced and a BLASTn search showed that the sequences (accession no. OR827305) shared the highest identity (99.3%) with that of P. cichorii strain 83-1 (accession no. DQ168848; 848/854 bp) and were 97.3% identical to the sequence of DSM 50259T (accession no. CP074349; 831/854 bp). Calc-A was selected as a representative strain and deposited in the Bioresource Collection and Research Center, Taiwan (reference no. BCRC 81432). Koch's postulates were fulfilled by spray-inoculating a suspension of Calc-A on three 2-mo-old C. hybrida F1 'Dainty' plants. The inoculum was prepared by suspending NA-grown cells in 10 mM MgCl2 including 0.02% Silwet L-77 (OD600 = 0.3; 1.5 x 108 CFU/ml). For the controls, three plants were sprayed with bacteria-free solution. The plants were bagged throughout the experiment and kept in a growth chamber (14/10 h light/dark; 26/24°C day/night). Leaf blight and wilting symptoms developed on all leaves of the inoculated plants after 30 h, but not the controls (Fig. S1, C and D). The pathogen was reisolated from the treatment group, and colony PCR with hrp1a/hrp2a showed that the reisolated strain shared the same sequence with Calc-A to Calc-C. Repeating the inoculation assay produced consistent results. This is the first report of P. cichorii affecting Calceolaria in Taiwan. The bacterium has been reported infecting diverse crops in Taiwan, such as tomato and lettuce (Tsai et al. 2014). Expanding the understanding of the pathogen's potential hosts could help prevent its spread across important crops.

First Report of White Mold Caused by Sclerotinia sclerotiorum on Echeveria gigantea in Mexico

Echeveria gigantea, native of Mexico (Reyes et al. 2011), holds economic importance as it is marketed as a potted plant and cut flower due to its drought-tolerant capabilities and aesthetic appeal. In September 2023, a field sampling was conducted at the Research Center in Horticulture and Native Plants (18°55'56.6" N, 98°24'01.5" W) of UPAEP University. Echeveria gigantea cv. Quilpalli plants with white mold symptoms were found in an area of 0.5 ha, with an incidence of 40% and severity of 50% on severely affected stems. The symptoms included chlorosis of older foliage, necrosis at the base of the stem, and soft rot with abundant white to gray mycelium and abundant production of irregular sclerotia resulting in wilted plants. The fungus was isolated from 30 symptomatic plants. Sclerotia were collected, sterilized in 3% NaOCl, rinsed with sterile distilled water (SDW), and plated on Potato Dextrose Agar (PDA) with sterile forceps. Subsequently, a dissecting needle was used to place fragments of mycelium directly on PDA. Plates were incubated at 23 °C in darkness. A total of 30 isolates were obtained using the hyphal-tip method, one from each diseased plant (15 isolates from sclerotia and 15 from mycelium). After 6 days, colonies had fast-growing, dense, cottony-white aerial mycelium forming irregular sclerotia of 3.67 ± 1.13 mm (n=100). Each Petri dish produced 32.47 ± 7.5 sclerotia (n=30), after 12 days. The sclerotia were initially white and gradually turned black. The isolates were tentatively identified as Sclerotinia sclerotiorum based on morphological characteristics (Saharan and Mehta 2008). Two isolates were selected for molecular identification. Genomic DNA was extracted using the CTAB protocol. The ITS region and the glyceraldehyde 3-phosphate dehydrogenase (G3PDH) gene were sequenced for two randomly selected isolates (White et al. 1990; Staats et al. 2005). The ITS and G3PDH sequences of the SsEg9 isolate were deposited in GenBank (ITS-OR816006; G3PDH-OR879212). BLAST analysis of the partial ITS (510 bp) and G3PDH (915 bp) sequences showed 100% and 99.78% similarity to S. sclerotiorum isolates (GenBank: MT101751 and MW082601). Pathogenicity was confirmed by inoculating 30 120-day-old E. gigantea cv. Quilpalli plants grown in pots with sterile soil. Ten sclerotia were deposited at the base of the stem, 10 mm below the soil surface. As control treatment, SDW was applied to 10 plants. The plants were placed in a greenhouse at 23 °C and 90% relative humidity. After 16 days, all inoculated plants displayed symptoms similar to those observed in the field. Control plants did not display any symptoms. The fungus was reisolated from the inoculated stems, fulfilling Koch's postulates. The pathogenicity tests were repeated three times. Recently S. sclerotiorum has been reported causing white mold on cabbage in the state of Puebla, Mexico (Terrones-Salgado et al. 2023). To the best of our knowledge, this is the first report of S. sclerotiorum causing white mold on E. gigantea in Mexico. Information about diseases affecting this plant is very limited, so this research is crucial for designing integrated management strategies and preventing spread to other production areas.

First Report of Stem and Foliage Blight of Chrysanthemum morifolium cv. Fubaiju Caused by Stagonosporopsis chrysanthemi in China

Chrysanthemum (Chrysanthemum morifolium cv. Fubaiju) is used as medicinal herb (Chen et al. 2020). In October 2021, a leaf spot disease was observed on leaves of C. morifolium in Huanggang, Hubei province. Disease incidence was approximately 40%. Leaf lesions manifested as necrotic spots, coalesced, and expanded to form brown-black spots, leading to wilting of the leaves. On stems, the lesions manifested as dark brown necrotic spots. To identify the pathogen, 29 pieces (5 × 5 mm) from lesion margins were surface sterilized in 1% NaOCl and rinsed three times with sterile water. The pieces were transferred onto potato dextrose agar (PDA) for incubation at 25℃ for 3 d in the dark. Fifteen fungal colonies were successfully isolated. The colony morphology with flat wavy edge, sparse aerial mycelia, and surface olivaceous black were observed at 7 days post incubation. Subglobular pycnidia were brown with a short beak, and pycnidia diameters were thick (212 to 265 × 189 to 363 µm, n = 20). Ovoid conidia were aseptate and hyaline, conidia diameters were thick (4.0 to 9.8 × 1.8 to 4.7 µm, n = 100). The morphological characters of these isolates were consistent with those of Stagonosporopsis chrysanthemi (Zhao et al. 2021). Pure culture of representative HGNU2021-18 isolated from the diseased leaves subjected to molecular identification. Sequences of the rDNA internal transcribed spacer (ITS) region, 28S large subunit ribosomal RNA (LSU), β-tubulin (TUB2), actin (ACT), and partial RNA polymerase II largest subunit (RPB2) genes were amplified from genomic DNA of isolate HGNU2021-18 using the following primer pairs: ITS1/ITS4 (White et al. 1990), LR0R/LR5 (Rehner et al. 1994), Btub2Fd/Btub4Rd (Woudenberg et al. 2009), ACT512F/ACT783R (Carbone et al.1999), and RPB2-5F2 (Sung et al. 2007)/fRPB2-7cR (Liu et al. 1999), respectively. The PCR products were purified and then sequenced by Sangon Biotech (China). Nucleotide sequences of ITS (544 bp, OM346748), LSU (905 bp, OM758418), TUB2 (563 bp, OM945724), ACT (294 bp, OM793715), and RPB2 (957 bp, OM793716) amplified from the isolate HGNU2021-18 were subjected to BLASTn analysis. The results showed that ITS, LSU, TUB2, ACT, and RPB2 shared 100.00%, 99.45%, 99.20%, 100.00%, and 100.00% sequence identity to the five published sequences (MW810272.1, MH869953.1, MW815129.1, JN251973.1, and MT018012.1, respectively) of the S. chrysanthemi isolate CBS 500.63. Phylogenetic analysis of the multilocus sequences of ITS, LSU, RPB2, ACT, and TUB2 belonging to different Stagonosporopsis species was performed in MEGA 7.0 (Chen et al. 2015). Isolate HGNU2021-18 was placed in a clade with S. chrysanthemi with 99% bootstrap support. Thus, the results of morphological and molecular analyses indicated that the disease symptoms on chrysanthemum plants were caused by S. chrysanthemi. Under conditions of 25°C and 85% relative humidity, pathogenicity test was performed on 2-month-old healthy plants using isolate HGNU2021-18. The leaves were inoculated with 5 mm diameter mycelial plugs or with sterile agar plugs (control). Six plants were used in each treatment. Disease symptoms were observed on treated plants at 2 weeks post inoculation which were those previously observed in the field, while the control plants remained symptomless. The pathogen was re-isolated from the diseased plants, and S. chrysanthemi was confirmed as the causal pathogen. This is the first report of S. chrysanthemi causing stem and foliage blight of chrysanthemum in China.

Transversotrema hafniensis n. sp. infection in Poecilia reticulata by cercariae released from Melanoides tuberculata in Denmark

BACKGROUND

Exotic and ornamental fish are highly popular companion animals resulting in a significant transcontinental trade of fish, invertebrates and aquatic plants. A major issue is the diseases associated with these organisms, as they have a major impact on health of the fish in both public and private household aquaria. A secondary issue is the trade with these products, which potentially may expand the distribution area and spread a range of diseases to new habitats.

RESULTS

We here describe how Poecilia reticulata (guppy), produced in a private household aquarium, were invaded by cercariae of an exotic trematode released by imported Melanoides tuberculata snails. The fish presented with severe clinical signs (tremor, flashing, scraping of body against objects). A standard parasitological examination and morphometric identification showed scale pocket infections with a digenean trematode species within the genus Transversotrema. Molecular identification by PCR, sequencing and phylogenetic analyses of a 2646 bp sequence encoding ribosomal RNA (partial 18 S, ITS1, 5.8 S, ITS2, partial 28 S) was performed. The 1107 bp sequence of mitochondrial DNA (cox1) showed that the parasite differed from previously described Transversotrema species in M. tuberculata. Morphometrics of adult and larval specimens of this isolate also differed from previously described freshwater species within the genus. The new species was described and is named after Copenhagen, for its geographic origin.

CONCLUSIONS

The genus Transversotrema comprises a range of species, adapted to a microhabitat in scalepockets of teleosts. A combination of morphological and molecular characterization techniques has been shown to provide a good differentiation between species. The fish were not purchased from a pet shop but produced in the home aquarium. This indicated that an infection pressure existed in the aquarium, where the source of infection was found to be exotic intermediate host snails M. tuberculata, which originally were imported and purchased from a pet shop. The potential spread of fish diseases associated with trade of fish and snails to new geographic regions, where climate conditions are favourable, is discussed.

Southern blight of water lily: The first host record of Agroathelia rolfsii on Nelumbo nucifera discovered in Florida, USA

Nelumbo nucifera Gaertn. (Nelumbonaceae, Eudicots), also known as water lily or sacred lotus, is a nonnative and invasive plant commonly found in artificial ponds and natural lakes throughout Florida (UF-IFAS 2023; Wunderlin et al. 2023). In August 2020, a single sample of water lily plants showing large leaf spots were collected at a residence in Dunnellon, Marion County, Florida (80% disease prevalence with 40% leaf coverage). Symptoms and signs of the disease were necrotized adaxial leaf spots only, bordered by whitish mycelia and hyphae with clamp connections, and whitish to light brown sclerotia formed in the center (<0.7 mm diameter). Symptomatic tissue was plated on acid potato dextrose agar (APDA) amended with chloramphenicol (100 mg/L) and ampicillin (30mg/L), and incubated at 20 °C for one week. Data supporting the molecular identification of this putative pathogen were gathered by PCR amplification and Sanger sequencing of the complete internal transcribed spacer (ITS) and a fragment of the large subunit (LSU) of the rRNA gene (~1.5 kb) using primers ITS1F and LR5 (FDACS-DPI PPST 2020-105211, GenBank OR492009) (White et al. 1990). The identification of the host was confirmed by Sanger sequencing of three plant barcode fragments: ITS2 (ITS2-S2F/ITS4, OR492008), ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) (rbcLa-F/rbcLa-R, GenBank OR502388), and Maturase K (matK) (matK-KIM1R/matK-KIM3F, GenBank OR502389) (Fazekas et al. 2012). MegaBLAST queries of the ITS/LSU sequence obtained here recovered a 99.61% match to the fungal pathogen Agroathelia (=Athelia) rolfsii (Sacc.) Redhead & Mullineux. (Redhead and Mullineux 2023) (Amylocorticiaceae, Agaricomycotina) strain GP3 (GenBank JABRWF010000005) (Yan et al. 2021). MegaBLAST queries of three host plant DNA barcodes recovered matches of greater than 99.62% similarity to N. nucifera sequences. After diagnosis, symptomatic dried leaf samples were deposited at Plant Industry Herbarium Gainesville (PIHG 17807) and an axenic culture was deposited at the Agricultural Research Services Culture Collection (NRRL 66964). Koch's postulates were fulfilled by the inoculation of sclerotia (as in Terrones-Salgado et al. 2022) on adaxial leaf surface of four-week- old water lily transplants obtained from an artificial pond on campus (two plants with five leaves each). One additional transplant was not inoculated and served as a control; this plant remained asymptomatic during the experimentation period. Each transplant was kept in a 27-gallon plastic container (21W × 30L × 14H in) filled with tap water containing one tablespoon of 20-20-20 all-purpose-water-soluble plant fertilizer (VPG, TX, USA) in a plant biosafety level 2 greenhouse (23 °C, >50% relative humidity, and a 12-h/12-h photoperiod). All inoculated leaves showed necrotized areas after one week and new sclerotia were observed floating on the water surface after three weeks. Fungal pathogen was reisolated and reidentified subsequently. Agroathelia rolfsii is the causal agent of southern blight, also known as grey rot, and is reported from at least in 260 plant genera, including specialty crops such as citrus, cucumber, pepper, peanuts, pumpkin, and strawberry (Farr and Rossman 2018). Agroathelia rolfsii usually causes lower stem, crown, and root rots; consequently, leaf spots are a noteworthy presentation of symptoms for this fungus.

First Report of the Rust Fungus Melampsora ferrinii on Salix babylonica in China and a New Spermogonial and Aecial Host, Corydalis bungeana

The occurrence of rust fungi on Corydalis bungeana Turcz. and Salix babylonica L. were found in same area of Hebei Province, China from 2022 to 2023. The life cycle connection of these rust fungi was suspected because Peng et al. (2022) reported the life cycle of Melampsora ferrinii Toome & Aime by inoculations, producing spermogonia and aecia on Corydalis species, and uredinia on S. babylonica. The morphology of the uredinial and telial stages on S. babylonica collected in the field was identical with the description of M. ferrinii by Toome and Aime (2015), and its identity was confirmed by phylogenetic analyses using the method of Ji et al. (2020) (LSU-PP087777, ITS-PP091274; Similarity with M. ferrinii: LSU-100%, ITS-99.85%). To confirm the life cycle of this rust fungus, inoculations were conducted on C. bungeana with basidiospores obtained from the teliospores on fallen leaves of Salix babylonica. The fallen leaves producing basidiospores were cut into small pieces (ca. 5 mm2) and placed on healthy leaves of C. bungeana. The inoculated plants were kept in a moist plastic box in darkness at 15-20℃ for 2 days and then transferred to the floor near windows at about 15-20℃ for observations. Ten days after inoculations small yellow spots of spermogonia appeared on the upper surface of the leaves of C. bungeana. About 7 days later, pale yellow aecia with aeciospores were produced mainly on the under surface of the leaves and petioles. The morphology of rust fungus on C. bungeana collected from the fields and obtained by inoculations was identical with the description by Peng et al. (2022). Phylogenetic analyses also showed that a specimen on C. bungeana collected from the field (LSU-OR607838, ITS-OR612063) were included into the same clade of M. ferrinii (Similarity: LSU-100 %, ITS-99.85). Based on morphology, inoculations and DNA sequence analyses, the rust fungi on C. bungeana and S. babylonica are identified as different stages of life cycle of M. ferrinii. This rust fungus has been reported to produce spermogonia and aecia on C. acuminata Franch., C. edulis Maxim. and C. racemosa (Thunb.) Pers. in China (Peng et al. 2022), and uredinia and telia on S. babylonica in USA, Argentina and Iran (Toome and Aime 2015, Abbasi et al. 2024), and on Salix sp. in Chile (Zapata 2016). Therefore, C. bungeana is a new host for M. ferrinii, and its field occurrence on S. babylonica is reported for the first time in China although Peng et al. (2022) reported successful results in its inoculations to S. babylonica in China. This report contributes to the control of rust diseases caused by this species. Specimens used in this experiment were deposited in the Fungal Herbarium of the Jilin Agricultural University, Changchun, China (HMJAU) and sequences newly analyzed were deposited in GenBank.

First report of Ralstonia pseudosolanacearum causing bacterial wilt on Rosa sp. in Greece

In March 2021, a sample of nine-month-old, non-grafted, diseased rose (Rosa sp.) plants was sent by a grower to the Benaki Phytopathological Institute for examination. The plants exhibited symptoms of dieback with black necrosis of pruned shoots, brown discoloration of shoot and root vascular tissues, and whitish slime exudation on cutting wounds of the shoots. The symptoms resembled those caused by Ralstonia pseudosolanacearum (Tjou-Tam-Sin et al. 2016). According to the sample's information sheet, the sample had been collected in a commercial greenhouse rose crop for cut flowers with a 10% disease incidence in the area of Troizinia-Methana (Regional Unit of Islands, Greece). Microscopic examination of symptomatic shoot and root vascular tissues revealed masses of bacterial cells streaming out of them. Sections of symptomatic tissues were suspended in water and in the resulting suspension, bacteria of the R. solanacearum species complex (RSSC) were detected by an indirect immunofluorescence (IF) assay using polyclonal antibodies (Plant Research International, the Netherlands) and a qPCR assay (RS-I-F/RS-II-R primers, RSP-55T probe) (Vreeburg et al. 2016). Furthermore, colonies with typical characteristics of RSSC were isolated from vascular tissues of shoots and roots on non-selective (NA) and semi-selective (mSMSA) media (EPPO 2022), and their identification as RSSC was confirmed by the above-mentioned IF and qPCR assays. Also, the isolates were assigned to: i) biovar 3, based on their ability to metabolize three disaccharides (maltose, lactose, D(+) cellobiose) and three hexose alcohols (mannitol, sorbitol, dulcitol) producing acid (EU 2006) and ii) phylotype I, by multiplex conventional PCR (Opina et al. 1997; Fegan and Prior 2005). A representative isolate was selected for sequencing part of the genes: 16S rDNA (1464bp), mutS (729bp) and egl (795bp) with GenBank Accession Nos. OR102443, OR683617 and OR702781, respectively. Blast analysis of these sequences showed 100% identity with those of various RSSC strains (e.g. GenBank Ac. Nos. CP025741.1, CP021762.1, MF141029.1, respectively). The obtained egl sequence conforms with the characteristics of phylotype I based on the DNA barcoding tool (EPPO 2021) and is 100% identical to that of the Dutch strain PD7216 (MF141029.1) reported to be sequevar I-33 (Bergsma-Vlami et al. 2018). The pathogenicity of two isolates was tested by inoculating: i) tomato seedlings (cv. 'Belladona') at their stem between the cotyledons and the first true leaf (EU 2006) and b) rose plants (cv. 'Aqua' and 'Papa Meilland') at their shoot base (Tjou-Tam-Sin et al. 2016), with bacterial suspensions in water (108 cfu/ml). The inoculated plants were maintained at a day/night temperature about 28/20°C with tomato plants exhibiting leaf wilting (7-17 dpi) and rose plants exhibiting chlorosis and necrosis of leaves (17 dpi). The pathogen was re-isolated on mSMSA from both artificially infected plant species and identified by the IF assay described above, thus fulfilling Koch's postulates. This is the first diagnosis in Greece of: i) rose plants infected by a Ralstonia species and ii) a crop infected by R. solanacearum phylotype I that corresponds to the R. pseudosolanacearum species (EPPO 2022). Official phytosanitary measures imposed in the affected area include an annual survey of rose crops for the presence of this pathogen, aiming at an early detection and prevention of its spread in such a highly valued ornamental crop.

First report of Dactylonectria pauciseptata causing root rot on Eucalyptus cinerea in China

Eucalyptus cinerea is an evergreen tree in the Myrtaceae. It is native to southern and eastern New South Wales and northern and eastern Victoria, Australia. It was introduced into China in the 1980s (Silva et al. 2011). Because of its unique shape, flexible stems, and rapid growth characteristics, it is widely used in the pulp industry and in decorative materials such as flower bouquets. In July 2022, 5- to 10-year-old E. cinerea showing symptoms of dehydration, withering and yellowing leaves, were found in forests and nurseries in Kunming and Songming, China. More than 37% of the trees showed these symptoms at each location, and disease severity was about 30%. Sixty symptomatic plants were collected from five tree nurseries. Diseased roots with 2-cm-long lesions were soaked in 75% ethanol for 15 s, 0.1% mercuric chloride for 2 min, rinsed with sterilized water, and placed on potato dextrose agar (PDA) at 25℃ for 3 days. Thirty samples were plated, and 21 isolates (YJLGF01 to YJLGF21) obtained, 11 strains with similar colony morphology (including representative strains YJLGF03 to YJLGF05). Three isolates (YJLGF03 to YJLGF05) were obtained by single-spore purification. On PDA, the colonies were circular with fluffy white to light yellow mycelium; the underside was yellowish brown. Conidiophores were bifurcated, with macroconidia borne terminally. The macroconidia were cylindrical with rounded, blunt ends, yellow to transparent, 1 to 3 septate (22.5 to 47.6 × 4.5 to 7.1 µm); microconidia were 0 to 1 septate (12.5 to 19.6 × 4.7 to 6.4 µm). Chlamydospores were spherical, rosary-like, and light yellow. Morphological characteristics were consistent with published descriptions of Dactylonectria pauciseptata (Piperkova et al. 2017). For molecular identification, the internal transcribed spacer (ITS), translation elongation factor 1- alpha (ef1-α) gene, and the beta-tubulin 2 (β-tub2) gene were amplified and sequenced (ITS accessions OR735053, OR735054, OR735055; β-tub2 accessios OR757447, OR757448, OR757449; ef1-α accessions OR757450, OR757451, OR757451) using published primers (White et al. 1990; Carbone et al. 1999). A phylogenetic tree was developed by Maximum Parsimony (MP) and Maximum Likelihood (ML) methods. These three isolates fell into the D. pauciseptata clade and were distinguished clearly from other species. Pathogenicity tests were performed using the same three isolates. Each isolate was cultured on PDA, and then subcultured in V8 juice broth on an orbital shaker at 180 RPM for 5 days. Conidia were collected by centrifugation at 6,000 RPM for 5 min, and then resuspended in sterilized distilled water (1×106 conidia/ml). Injured roots of one-year-old E. cinerea were soaked in the spore suspension for 1 h before being transplanted in sterile vermiculite. The plants were incubated at 25℃ with a 12 h photoperiod and 90% humidity. Five plants were inoculated as a group for each treatment and the entire experiment was completed three times. Among the inoculated plants, the incidence of disease development was 100%. A small sot appeared after 4 days, with a water-soaked lesion appearing and gradually expanding during days 5 to 7. After 10 days symptoms of root necrosis were similar to the those observed in the nursery, and aboveground plant parts had yellow, withering leaves and defoliation after 10 to 15 days. Control plants treated with sterile water showed no disease symptoms. The three strains were successfully reisolated from inoculated seedlings and confirmed them using DNA sequencing. No isolates were obtained from the control plants, thus fulfilling Koch's postulates. Dactylonectria pauciseptata was first reported from necrotic tissue of infected grape roots (Schroers et al. 2008). So far, it has been reported in Turkey, Canada, Brazil, Italy, and other countries (Erper et al. 2013; Úrbez-Torres et al. 2014; Santos et al. 2014). Based on our results, E. cinerea is a new host plant of D. pauciseptata in China. This disease is a threat to the nursery production of E. cinerea, potentially leading to a reduction in yields and economic losses.

First Report of Root Rot Caused by Fusarium incarnatum on Mongolian Snake gourd in China

Mongolian snake gourd (Trichosanthes kirilowii Maxim) is a precious traditional Chinese herbal medicine and perennial liana plant in the family Cucurbitaceae, and the root, fruit, seed and peel all possess the medicinal value (Zhang et al. 2016). During 2021-2022, the root rot was observed in a 20-ha commercial farm and became a major disease limiting Mongolian snake gourd production in Zhenjiang City, Jiangsu Province, China (119°27'E, 32°12'N). Field investigations showed that disease incidence was estimated at approximately 70% and resulted in up to a 50% decrease in total production. Symptoms on snake gourd initially appeared as yellow mottling produced on the surface of the infected new leaves and systemic wilting on the upper leaves. With the development of the infection, the base of the stem began to brown and die, and has lots of filamentous hyphae attached to it. As the lesions coalesced, the whole plant gradually wilted and died. In order to explore the cause of the disease, six infected plants were randomly collected from the commercial farm. The roots of the plants were rinsed in sterile water to remove soil debris, and symptomatic roots were surface sterilized using 75% ethanol for 60s, rinsed three times in sterile water, then plated onto the potato dextrose agar (PDA), and incubated at 25°C for 3 days in the dark. White fungal colonies grew from the tissue pieces, then hyphal tips were transferred to PDA to obtain pure cultures. A total of six isolates with similar morphological characteristics were obtained from six of the infected plants. One representative isolate GL21091501 was chosen for further analysis. At 5 days after inoculation, the colonies on PDA began to grow as white, and with the incubated time was extended, the hyphae turned yellowish-brown with a yellowish-brown center on the reverse side. Observations under a light microscope showed conidia that were falculate, slender and slightly curved, and the cells at both ends were sharp. Macroconidia had four to five septa, measuring 22.4 ~ 33.5 μm. Microconidia without septa, elliptical, measuring 4.36 ~ 9.88 μm. On the tip of aerial hyphae can form conidiophore, and produce macroconidia (Wonglom et al. 2020; Lin et al 2018). The pathogen was typical Fusarium spp. by morphological characteristics. To identify the species level, the mycelia of the representative isolate GL21091501 was used for genomic DNA extraction (Tiangen, China). The internal transcribed spacer (ITS) region and partial translational elongation factor subunit 1-α (TEF-1α) of the cultures were amplified and sequenced using the primer pairs EF1/EF2 and ITS1/ITS4 respectively (White et al. 1990; O'Donnell et al. 1998). The obtained sequences were deposited in GenBank under the accesion numbers OP311409 and OP311410. BLAST searches of the deposited sequences showed 100% identity with the existing TEF sequences (MT563420.1) and ITS sequences (MN539094.1) of Fusarium incarnatum isolates in GenBank. In addition, BLASTn analysis of these in FUSARIUM-ID database showed 99.62% and 100% similarity with F. incarnatum-equiseti species complex (FIESC) NRRL13379 [ITS] and NRRL34004 [TEF-1α]), respectively. Phylogenetic analysis was conducted with the neighbor-joining (NJ) method using MEGA6.0 (Tamura et al. 2007). Combined phylogenetic analysis revealed that the isolate shared a common clade with the reference sequence of F. incarnatum in the F. incarnatum-equiseti species complex. Therefore, according to morphological and molecular characteristics confirming the identity of the isolated pathogen as F. incarnatum. In order to fulfill Koch's postulates, fresh isolate GL21091501 hyphae were cut into 3 × 3 mm agar plugs from a 7 cm PDA plate and inoculated in 200 mL the Potato Dextrose (PD) liquid medium on a shaker at 170 rpm, 25°C for 5 days. Spores were filtered through four layers of gauze, adjusted to 1 × 106 spores/ml with sterilized water. Then Mongolian snake gourd seedlings at the two true leaves stage were transplanted in (15-cm-diameter) pots (1 plants/pot) filled with mixture of sterilized soil: vermiculite: pearlite (2:1:1, v/v). The pathogenicity test was conducted on seedlings plants by root irrigation method (50 ml/plant, 1×106 conidia/mL), control plants were irrigation with sterilized water (50 ml/plant). Each treatment was repeated three times. After 15 days, all inoculated plants showed the same symptoms observed on the original diseased plants in the field, whereas, the control plants remained symptomless. The same pathogen was successfully re-isolated from the inoculated plants, and identical to those of the originals based on morphological and sequence data. To our knowledge, this is the first report of F. incarnatum causing root rot on Mongolian snake gourd in China. F. incarnatum has been reported to cause root and stem rot in many plants worldwide, including muskmelon (Wonglom et al. 2020), Cucurbita pepo (Thomas et al. 2019) and Bambusa multiplex (Lin et al. 2018). This discovery is of great importance for Mongolian snake gourd planters because the fungus is accurately identified in a certain geographic area and effective field management strategies are necessary to control this disease.

Occurrence of Fusarium fujikuroi Causing Fusarium Wilt on Carthusian Pink in China

Carthusian pink (Dianthus carthusianorum) is native to Europe and is widely grown in China for landscaping. In September 2022, wilting symptoms of carthusian pink were found in Xixia City (33°18'31″ N, 111°29'45″ E), Henan Province, China, with a disease incidence of 65%. Approximately 100 plants were surveyed on the landscaping lawns of the park. Initial symptoms were yellow to brown lesions on the base of stems and leaves. Later, the lesions spread throughout the plants, turning leaves yellow, and leading to root and leaf rot. Eventually, the plants shriveled and died (Figure S1a). Thirty diseased tissues isolated from the roots and leaves were cut into 5×5 mm pieces, which were surface sterilized with 75% ethanol solution for 30 seconds and 1% NaClO solution for 1 minute, rinsed three times in sterilized water, placed on potato dextrose agar (PDA) plates supplemented with 50 μg ml-1 streptomycin, and incubated at 28°C for five days. A total of 25 purified fungal strains with similar phenotypic features were obtained. Three representative strains named OSZ-P1, OSZ-P2, and OSZ-P3 were selected for identification. Fungal colonies developed an abundant aerial mycelium, initially white, which subsequently developed red to purple pigments (Figure S1b). Macroconidia were slender, straight, and measured 12.74 to 49.39 × 2.07 to 4.39 μm (n=50), with two to five septa. Microconidia were clavate and measured 6.31 to 11.61 × 2.15 to 4.02 μm (n=50) (Figure S1c). These morphological characteristics were consistent with Fusarium spp.. The rDNA internal transcribed spacer (ITS), β-tubulin gene (tub2), translation elongation factor 1-alpha gene (tef1), calmodulin (cmdA), RNA polymerase largest subunit (rpb1), and RNA polymerase II second largest subunit (rpb2) were amplified with primers ITS1/ITS4, BT-2a/BT-2b, EF1/EF2, CL1/CL2A, Fa/G2R, and 5F2/7Cr, respectively, for further identification (Yilmaz et al. 2021, O'Donnell et al. 2022). ITS (OQ726389, OQ726390, OQ726391), tub2 (OQ730191, OQ789645, OQ789646), tef1 (OR088904, OR088905, OR088906), cmdA (OR133730, OR133731, OR133732), rpb1 (OR088907, OR088908, OR133729), and rpb2 (OR133733, OR133734, OR133735) nucleotide sequences of the strains OSZ-P1, OSZ-P2, and OSZ-P3 were submitted to GenBank. BLASTn analysis of OSZ-P1 sequences exhibited 99 to 100% similarity with Fusarium fujikuroi sequences (strains Augusto2, I1.3, and CSV1) CP023096, CP023108, CP023084 of cmdA, CP023089, CP023077 of rpb1, and CP023093, CP023105, CP023081 of rpb2. A Phylogenetic tree was constructed of combined genes (tub2, tef1, cmdA, rpb1, rpb2) of sequences, alongside the sequences of the type strains by the neighbor-joining method. The three strains formed a clade with the type strains CBS257.52 and Augusto2 of F. fujikuroi in phylogenetic trees, being clearly separated from other Fusarium spp. (Figure S2). The morphological features and molecular analyses supported the strains as members of F. fujikuroi. To verify the pathogenicity, aboveground parts of the plants of five healthy six-month-old potted plants were sprayed with 100 µl of conidial suspension per pot (106 conidia ml-1), and five similar plants were sprayed with sterilized water as a control. All plants were placed in a climate incubator at 28°C and 90% relative humidity. Seven days after inoculation, withered and yellowed lesions were observed, similar to the natural lesions (Figure S1e). No symptoms were observed on the control plants. The whole pathogenicity tests were performed thrice. Reisolation resulted in cultures that were morphologically and molecularly identical to the original isolates, fulfilling Koch's postulates. Fusarium wilt disease has been reported on other plants of the genus Dianthus. Vascular wilt on Dianthus caryophyllus (carnation) caused by Fusarium oxysporum is the most destructive disease of carnation crops worldwide (Ardila et al. 2014). Fusarium acuminatum causing Dianthus chinensis root rot and foliage blight has recently been reported in Nanjing, China (Xu et al. 2022). To our knowledge, this is the first report of F. fujikuroi causing Fusarium wilt on carthusian pink worldwide. The host range of F. fujikuroi still needs to be clarified for accurate disease management in the selection of plant species for landscape.

First Report of rattail cactus necrosis-associated virus Infecting Prickly pear (Opuntia macrocentra) in the United States

Black-spined prickly pear (Opuntia macrocentra Engelmann; Cactaceae) is a cactus native to Arizona, New Mexico, Texas, and northwest Mexico. The plant is often grown for ornamental purposes in the United States. In February 2023, virus-like symptoms such as concentric ringspots and chlorotic spots were observed on O. macrocentra plants grown at the vicinity of Maricopa County Cooperative extension, University of Arizona, Phoenix, AZ (33°24'24.6"N, 111°59'15.3"W). Total RNA was extracted from two samples (YPHC-60-A and YPHC-60-B), following the protocol by Tzanetakis et al. (2007). Reverse transcription polymerase chain reaction (RT-PCR) was performed with degenerate tobamovirus, TobamodF/TobamodR (Li et al. 2018) and potexvirus, 1RC, Potex 2RC, and Potex 5 (van der Vlugt and Berendsen 2002) primers. An expected amplicon of ~880 bp was obtained from both samples using TobamodF/TobamodR primers, while no amplification was observed with potexvirus primers. Further, RT-PCR was carried out using species-specific primers to detect cacti related tobamoviruses: cactus mild mottle virus (CMMoV), rattail cactus necrosis-associated virus (RCNaV) (Park et al. 2018) and Opuntia virus 2 (Salgado-Ortiz et al. 2020). Amplicons of ~540 bp were amplified from both samples using RCNaV specific primers, whereas no amplification was obtained using CMMoV and Opuntia virus 2 specific primers. Then, the amplicons from both YPHC-60 (A-B) isolates (~540 bp) were Sanger sequenced and shared 99.22% nucleotide identity to each other. A BLAST search revealed 93% nucleotide identity with RCNaV CP sequences (KY581586.1, JF729471, and MT130378.1). The sequences were submitted in the GenBank (accessions no. OQ914798 and OR828526). Furthermore, complete RCNaV- RNA dependent RNA polymerase (RdRP) gene was amplified using primers 3490-s-5'GTAGGTGGTACCGCATAGCA-3'; 3490as 5'AAACGCAAGTCMRYGACYGA-3' (designed in this study from accession no. JF729471.1, position 3490-3509 and 4905-4925). The expected amplicons of ~1,500 bp were obtained from both YPHC-60 (A-B) samples and sequenced (GenBank: OQ914799 and OR823954) showing 87.5 % identity with RCNaV sequences (JF729471.1 and NC_016442.1). The maximum-likelihood phylogenetic tree clustered YPHC-60 (A-B) isolates in a single clade with other RCNaV isolates. RCNaV virus particles were isolated from YPHC-60 (A-B) and submitted for RNA extraction, testing positive for RCNaV by RT-PCR. Sap extract of YPHC-60 (A-B) prepared in 0.01 M phosphate buffer (pH =7.0) was used to mechanically inoculate 3 indicator plant species (n=10): Phaseolus vulgaris, Medicago sativa, and Cucumis melo. Also, infected tissue was used to graft Opuntia sp. plants. Symptoms such as local lesions were observed on M. sativa and vein thickening on P. vulgaris 14 days post-inoculation, while Opuntia sp. showed chlorosis 30 days after grafting. RCNaV infection in mechanically inoculated P. vulgaris, M. sativa, and Opuntia sp. was also confirmed through RT-PCR. C. melo and non-inoculated control plants did not show any symptoms, nor tested positive through RT-PCR. RCNaV has been reported earlier to infect cactus species in South Korea (Park et al. 2018) and O. albicarpa in Mexico (De La Torre-Almaráz et al. 2016), where it was found in several orchards. To the best of our knowledge, this is the first report of RCNaV infecting O. macrocentra in the United States. This study highlights that RCNaV is easily transmitted mechanically or by grafting, which could impact the nursery industry as most cacti are clonally propagated.