Characterizing the Brown Spot Pathosystem in Late-Harvest Table Grapes (Vitis vinifera L.) in the California Central Valley

Recent advances in biocontrol and other alternative strategies for the management of postharvest decay in table grapes

During postharvest, table grapes are often spoiled by molds. Aspergillus sp., Alternaria sp., Botrytis sp., Cladosporium sp. and Penicillium sp. are different mold genera frequently related to table grape rot. Fungal spoilage affects nutritional value and organoleptic properties while also producing health hazards, such as mycotoxins. Traditionally, synthetic fungicides have been employed to control fungal diseases. However, possible negative effects on health and the environment are a serious concern for consumers and government entities. This review summarized data on innovative strategies proposed to diminish postharvest losses and extend table grape shelf life. Among physical, chemical, and biological strategies, either alone or in combination, the integrated management of fungal diseases is a sustainable alternative to synthetic fungicides. However, to date, only a few alternative technologies have succeeded on a commercial scale. Recent research aimed at increasing the competitiveness of alternative technologies has led to the development of integrated management strategies to prevent postharvest decay and increase the safety and quality of table grapes.

Effect of biological treatment used before harvesting and storage methods on the quality, health and microbial characteristics of unripe hazelnut in the husk (Corylus avellana L.)

BACKGROUND

The hazelnut (Corylus avellana) is still one of the most profitable nut crop species. In recent years, however, there has been growing interest in this species in the form of "fresh nuts" that are picked before falling out of the fruit cover. The aim of this study was to evaluate the effect of storage conditions for hazelnuts protected with biological preparations on selected morphological features of the fruits, their health status and the count of bacteria and fungi colonizing the fruits.

RESULTS

The hazelnuts harvested from the trees protected with a preparation containing Pythium oligandrum and stored for 2 months under the controlled atmosphere conditions and in Xtend® bags (MAP) had the greatest weight and the highest percentage of the kernel. After 3 months of storage, the hazelnuts had reduced commercial value. Only a few hazelnuts displayed symptoms of infectious diseases caused by species of Botrytis and Monilia. The protection applied before the hazelnut harvesting contributed to a multiple increase in the bacterial and yeasts count on the husks and shells of the hazelnuts stored for 3 months. The bacterial count on the nuts stored under the controlled atmosphere (CA, 3%O₂:3%CO₂, a temperature of 0-1 °C, humidity of 85-95%) and under the controlled atmosphere conditions and in Xtend® bags (MAP) increased significantly. An analysis of the ITS region sequence revealed the presence of bacteria Arthrobacter luteolus and Pantoea agglomerans. A Koch test proved that both non-pathogenic bacteria and pathogenic fungi can cause the browning of the C. avellana leaf under conditions of high humidity. The application of a controlled atmosphere is recommended for a short-term storage of hazelnuts in the husk.

CONCLUSION

This research showed that 2 months' storage of hazelnuts under controlled atmosphere conditions and Xtend® bags (MAP) prevented a reduction in the weight of hazelnuts in the husk, without the husk, and of the kernel and prevented the nut separation from the husk. In general, the application of biopreparations for the protection of the hazelnut had a positive effect on the kernel weight and size.

Microbial networks inferred from environmental DNA data for biomonitoring ecosystem change: Strengths and pitfalls

Environmental DNA contains information on the species interaction networks that support ecosystem functions and services. Next-generation biomonitoring proposes the use of this data to reconstruct ecological networks in real time and then compute network-level properties to assess ecosystem change. We investigated the relevance of this proposal by assessing: (i) the replicability of DNA-based networks in the absence of ecosystem change, and (ii) the benefits and shortcomings of community- and network-level properties for monitoring change. We selected crop-associated microbial networks as a case study because they support disease regulation services in agroecosystems and analysed their response to change in agricultural practice between organic and conventional systems. Using two statistical methods of network inference, we showed that network-level properties, especially β-properties, could detect change. Moreover, consensus networks revealed robust signals of interactions between the most abundant species, which differed between agricultural systems. These findings complemented those obtained with community-level data that showed, in particular, a greater microbial diversity in the organic system. The limitations of network-level data included (i) the very high variability of network replicates within each system; (ii) the low number of network replicates per system, due to the large number of samples needed to build each network; and (iii) the difficulty in interpreting links of inferred networks. Tools and frameworks developed over the last decade to infer and compare microbial networks are therefore relevant to biomonitoring, provided that the DNA metabarcoding data sets are large enough to build many network replicates and progress is made to increase network replicability and interpretation.

Associations Between Drosophila suzukii (Diptera: Drosophilidae) and Fungi in Raspberries

The invasive vinegar fly, Drosophila suzukii Matsumura, has emerged as one of the most serious arthropod pests of primocane red raspberries (Rubus ideaus L.) in the United States. In raspberries, D. suzukii encounter a diverse community of microbes, including fruit rot pathogens such as Botrytis cinerea Pers and Cladosporium cladosporioides de Vries. In this study, our primary objectives were to evaluate D. suzukii-fungal associations and determine D. suzukii's influence on fungal communities in raspberry fruit. Through culture-based surveys of larval gut microbes, we isolated several yeast fungi (primarily Hanseniaspora spp.), as well as Cladosporium, Botrytis, and several other non-yeast fungi from larval frass, suggesting that D. suzukii larvae encounter and feed on these fungi. Subsequent field surveys confirmed that D. suzukii larvae occurred in berries affected by Botrytis fruit rot and Cladosporium fruit rot. Under laboratory conditions, D. suzukii may facilitate C. cladosporioides infections, likely through the introduction of epiphytic propagules on the fruit surface. We could not detect impacts on B. cinerea infections or establish a clear vectoring relationship for either fruit rot. These studies provide evidence for an association between D. suzukii and fungal fruit rot pathogens. Understanding interactions between raspberry fruit, D. suzukii, and fungal microbes-especially whether D. suzukii facilitates the development of fruit rots or conversely, if fruit rots influence D. suzukii infestation patterns-may improve pest and pathogen management programs.