Quantification of Botrytis cinerea in Grapevine Bunch Trash by Real-Time PCR

Quantification of colonization of grape bunch trash by Botrytis cinerea is crucial for Botrytis bunch rot (BBR) control. A previously developed quantitative polymerase chain reaction (qPCR) method was adapted to quantify B. cinerea DNA in grape bunch trash, and a colonization coefficient (CC) was calculated as the ratio between the DNA concentrations of B. cinerea and of Vitis vinifera. CC values increased linearly with the number of conidia of B. cinerea or the quantity of mycelium of B. cinerea added to the bunch trash increased. CC values also increased linearly in bunch trash samples containing increasing percentages of B. cinerea-colonized bunch trash; in the latter samples, CC values were correlated with subsequent assessments of B. cinerea colonization of trash (as determined by plating on agar) and sporulation on the trash (as determined by spore counts after incubation in humid chambers). The qPCR assay was also validated using trash collected from bunches treated or not treated with fungicides in three vineyards in two seasons. CC values reflected the reduction in sporulation and in latent infections of mature berries caused by fungicide application. The qPCR assay enables rapid, specific, sensitive, and reliable quantification of the degree of colonization of bunch trash by B. cinerea, which makes it a useful tool for studies of the epidemiology and management of BBR

Exploit biodiversity in viticultural systems to reduce pest damage and pesticide use, and increase ecosystems services provision: the BIOVINE Project

Organic vineyards still rely on large external inputs to control harmful organisms (i.e., pests). The BIOVINE project aims to develop natural solutions based on plant diversity to control pests and reduce pesticide dependence. The capability of plants of increasing the ecosystem resistance to pests and invasive species is a well-known ecosystem service. However, monocultures (including vineyards) do not exploit the potential of plant diversity. BIOVINE aims to develop new viticultural systems based on increased plant diversity within (e.g., cover crops) and/or around (e.g., hedges, vegetation spots, edgings) vineyards by planting selected plant species for the control of arthropods, soil-borne pests (oomycetes, fungi, nematodes), and foliar pathogens. Candidate plants will be identified by a literature review, and the selected ones will be tested in controlled environment or small-scale experiments. The ability of the selected plants to: i) attract or repel target arthropod pests; ii) conserve/promote beneficials; iii) control soil-borne pests by means of biofumigation; iv) carry mycorrhizal fungi to the vine root system to increase plant health (growth and resistance); and v) control foliar pathogens by reducing the inoculum spread from soil, will be investigated. New viticultural systems able to exploit plant diversity will then be designed based on results of BIOVINE activities, following a design-assessment-adjustment cycle, which will then be tested by in-vineyard experiments in France, Italy, Romania, Slovenia, Spain and Switzerland for a 2-year period. Innovative viticultural systems should represent an improved way for pest control in organic viticulture, meanwhile they should positively affect functional biodiversity and ecosystem services. New control strategies may provide financial opportunities to vine growers and lower their reliance on pesticides

Reduction of Botrytis cinerea Colonization of and Sporulation on Bunch Trash.

Botrytis bunch rot (BBR) of grapevine, caused by Botrytis cinerea, is commonly managed by fungicide (FUN) sprays at flowering (A), at prebunch closure (B), at veraison (C), and before harvest. Applications at A, B, and C are recommended to reduce B. cinerea colonization of bunch trash and the production of conidia during berry ripening. The effects of these applications were previously evaluated as reductions in BBR severity at harvest rather than as reductions in bunch trash colonization and sporulation by B. cinerea. This study investigated the effects of FUNs (a commercial mixture of fludioxonil and cyprodonil), biological control agents (BCAs; Aureobasium pullulans and Trichoderma atroviride), and botanicals (BOTs; a commercial mixture of eugenol, geraniol, and thymol) applied at different timings (A, B, C, or ABC) compared with a nontreated control (NT) on B. cinerea bunch trash colonization and sporulation in vineyards. The ability of B. cinerea to colonize the bunch trash (as indicated by B. cinerea DNA content) and sporulate (as indicated by the number of conidia produced under optimal laboratory conditions) was highly variable, and this variability was higher between years (2015 to 2018) than among the three vineyards and three sampling times (i.e., 1 week after applications at A, B, and C). B. cinerea sporulation on bunch trash was significantly lower in plots treated with FUN than in NT in only 3 of 18 cases (3 vineyards × 2 years × 3 sampling times). FUN applications, however, significantly reduced B. cinerea colonization of bunch trash compared with NT; for colonization, BCA efficacy was similar to that of FUN, but BOT efficacy was variable. For all products, colonization reduction was the same with application at A versus ABC, meaning that the effect of an early season application lasted from flowering to 1 week after veraison. These results indicate that the early season control of B. cinerea is important to reduce the saprophytic colonization of bunch trash, especially when the risk of BBR is high

Helping farmers in timing the application of biocontrol agents in viticulture.

Directive 128/2009/EC on the Sustainable Use of Pesticides encourages EU Member States to promote low pesticide-input pest control by the implementation of tools for pest monitoring and decision making, and by giving priority to non-chemical methods, including the use of biological control agents (BCAs). Although the intensive research developed in the last decades the practical use of BCAs is still challenging. Biocontrol of plant diseases involves complex interactions between two living organisms (the pathogen and the BCA), the plant and the environment. To achieve effective disease management is then crucial having knowledge on: (i) the life cycle of both, the pathogen and the BCA; (ii) the mode of action of the BCA against the pathogen; and (iii) how the two are influenced by the environment. Mathematical models for pathogen and BCAs could help understanding these relationships and then contributing to optimisation of the BCA applications. In this work, two examples are presented on how the use of BCAs can be improved by using mathematical modelling: Ampelomyces spp. hyperparasites against Erysiphe necator (the grape powdery mildew fungus), and BCAs against Botrytis cinerea (causing Botrytis bunch rot in grapes)