gloeosporioides Species Complexes

Natural infection by Colletotrichum spp. and the subsequent development of ripe rot were observed in susceptible grape (Vitis vinifera) clusters either protected or exposed to environmental conditions and naturally occurring inoculum by the application or removal of paper bags at various phenological stages at two Mid-Atlantic vineyards. During each of the three experimental seasons, most treatments with grape clusters that were exposed between veraison and harvest developed significantly more severe ripe rot than clusters that were exposed during only the early season or protected throughout the entire season. Spore traps were placed in one vineyard over two seasons and were analyzed via quantitative PCR. DNA of the Colletotrichum acutatum and C. gloeosporioides species complexes was detected from the bloom to the harvest stage, with a higher quantity of C. acutatum DNA than C. gloeosporioides DNA. From ripe rot symptomatic clusters, 417 isolates were collected, and a multilocus phylogenetic analysis of 51 representative isolates identified six Colletotrichum spp., with C. fioriniae (C. acutatum complex) being the most frequently isolated. Weather data were also monitored, and ripe rot-conducive conditions were observed at multiple times throughout each season. In summary, only clusters that were exposed to inoculum and environmental conditions in the late season developed severe ripe rot. The data collected in this study suggest that grape clusters have ontogenic susceptibility to ripe rot, becoming more susceptible as they mature, in contrast to the susceptible bloom stage for other fruit rotting diseases of grapevine.

Rotting Grapes Don't Improve with Age: Cluster Rot Disease Complexes, Management, and Future Prospects

Cluster rots can be devastating to grape production around the world. There are several late-season rots that can affect grape berries, including Botrytis bunch rot, sour rot, black rot, Phomopsis fruit rot, bitter rot, and ripe rot. Tight-clustered varieties such as 'Pinot gris', 'Pinot noir', and 'Vignoles' are particularly susceptible to cluster rots. Symptoms or signs for these rots range from discolored berries or gray-brown sporulation in Botrytis bunch rot to sour rot, which smells distinctly of vinegar due to the presence of acetic acid bacteria. This review discusses the common symptoms and disease cycles of these different cluster rots. It also includes useful updates on disease diagnostics and management practices, including cultural practices in commercial vineyards and future prospects for disease management. By understanding what drives the development of different cluster rots, researchers will be able to identify new avenues for research to control these critical pathogens.

Isolation and Characterization of Endophyte Bacillus velezensis KOF112 from Grapevine Shoot Xylem as Biological Control Agent for Fungal Diseases

As the use of chemical fungicides has raised environmental concerns, biological control agents have attracted interest as an alternative to chemical fungicides for plant-disease control. In this study, we attempted to explore biological control agents for three fungal phytopathogens causing downy mildew, gray mold, and ripe rot in grapevines, which are derived from shoot xylem of grapevines. KOF112, which was isolated from the Japanese indigenous wine grape Vitis sp. cv. Koshu, inhibited mycelial growth of Botrytis cinerea, Colletotrichum gloeosporioides, and Phytophthora infestans. The KOF112-inhibited mycelial tips were swollen or ruptured, suggesting that KOF112 produces antifungal substances. Analysis of the 16S rDNA sequence revealed that KOF112 is a strain of Bacillus velezensis. Comparative genome analysis indicated significant differences in the synthesis of non-ribosomal synthesized antimicrobial peptides and polyketides between KOF112 and the antagonistic B. velezensis FZB42. KOF112 showed biocontrol activities against gray mold caused by B. cinerea, anthracnose by C. gloeosporioides, and downy mildew by Plasmopara viticola. In the KOF112–P. viticola interaction, KOF112 inhibited zoospore release from P. viticola zoosporangia but not zoospore germination. In addition, KOF112 drastically upregulated the expression of genes encoding class IV chitinase and β-1,3-glucanase in grape leaves, suggesting that KOF112 also works as a biotic elicitor in grapevine. Because it is considered that endophytic KOF112 can colonize well in and/or on grapevine, KOF112 may contribute to pest-management strategies in viticulture and potentially reduce the frequency of chemical fungicide application.

Validation of a Decision Support System for Blueberry Anthracnose and Fungicide Sensitivity of Colletotrichum gloeosporioides Isolates

Blueberry is an increasingly important crop in Florida. Anthracnose fruit rot (AFR), caused mostly by Colletotrichum gloeosporioides, is favored by long wetness periods and temperatures from 15 to 27°C. Currently, the model in the Strawberry Advisory System (StAS) guides fungicide applications targeting strawberry AFR. Given the similarity between blueberry and strawberry AFR, we hypothesized that the model used in StAS could be used in a decision support system (DSS) built for blueberry AFR. There is no information on inhibition posed by fungicides on C. gloeosporioides isolates from blueberry. Our objectives were to demonstrate that the model used in the StAS could be used for blueberry AFR management in Florida and to assess the sensitivity of isolates to fungicides. Four trials were undertaken in blueberry fields in Florida during two seasons to compare the effectiveness of fungicide applications according to the model with that of the growers' standard calendar. Sensitivity of blueberry C. gloeosporioides isolates to azoxystrobin, benzovindiflupyr, penthiopyrad, pydiflumetofen, boscalid, thiophanate-methyl, fluazinam, and fludioxonil was evaluated. AFR incidence and yield were compared between treatments. Following recommendations from the model resulted in disease control as effective as the standard program and in some cases with fewer applications. All isolates were sensitive to benzovindiflupyr, penthiopyrad, fluazinam, and fludioxonil. Low frequency of in vitro inhibition of isolates by azoxystrobin, pydiflumetofen, boscalid, and thiophanate-methyl should raise concern about fungicide resistance. Our results indicate that the model used in StAS could be used in a DSS to help Florida growers to manage AFR in blueberry.

A First Assessment of the Cranberry Fruit Rot Complex in Michigan

Samples of ripe fruit were taken at harvest from all eight commercial cranberry farms in Michigan over a 3-year period to determine the distribution and incidence of fruit rot diseases and the fungal pathogens associated with rotted fruit. Totals of 23, 33, and 28 beds were sampled in 1999, 2000, and 2001, respectively. Fruit rot incidence varied widely among beds and farms and ranged from 5 to 97% (mean 33.4%) in 1999, 1 to 91% (mean 26.3%) in 2000, and 1 to 67% (mean 12.8%) in 2001. Differences in fruit rot incidence were observed among cultivars, but rankings differed among farms. In general, cultivars Ben Lear, Bergman, and Pilgrim tended to have lower and Beckwith and WSU61 higher fruit rot incidence than other cultivars grown in the same location. Colletotrichum acutatum, Pestalotia vaccinii, and Phyllosticta vaccinii were the fungi most frequently recovered from rotted fruit. Fusicoccum putrefaciens, Phomopsis vaccinii, Physalospora vaccinii, Allantophomopsis lycopodina, Coleophoma empetri, and Botrytis cinerea were isolated occasionally in 1999. The isolation frequency of Physalospora vaccinii, Phomopsis vaccinii, and C. empetri increased markedly in 2000. Glomerella cingulata was first detected in 2001. Fusicoccum putrefaciens was most common in the northern and Glomerella cingulata in the southern growing areas. A comparison of sound and rotted fruit from selected beds showed that Phyllosticta elongata predominated in sound fruit, whereas G. cingulata predominated in rotted fruit.