Mode of action of a fatty acid-based natural product to control Botrytis cinerea in grapes.

AIMS: To investigate the efficacy and mode of action of the fatty acid-based product Foodcoat(®) (FC) against Botrytis cinerea. METHODS AND RESULTS: In vitro, in vivo and field experiments were carried out to investigate the effect of different concentrations of FC on B. cinerea germination and infection of grape leaves and berries, using three selected isolates and comparing results with those achieved by the commercialized product Protector(HML) (PRT). Furthermore, the effect of field applications of FC on the grape berry microbiota was investigated. FC reduced B. cinerea germination and grape berry severity by up to 54 and 96%, respectively, compared with the untreated controls. CONCLUSIONS: Foodcoat demonstrated efficacy that was equal or greater than the registered product, PRT. A multiple mode of action was hypothesized for FC suppression of B. cinerea, including: inhibition of germination and germ tube alteration, protection of host green tissues and enhancement of the natural yeast populations on the berry surface. SIGNIFICANCE AND IMPACT OF THE STUDY: The efficacy of both products has been quantified and their modes of action described, suggesting them for field applications against B. cinerea, alone or in combined strategies. This is also the first report of a fatty acid-based product stimulating natural yeast populations on grape berries.

Waste stream utilisation for sustainable viticulture.

Field trials were established at four vineyards in January 1999 to evaluate the effects of four mulch mixtures on different soil and plant parameters. Mulches were made from wine industry and other commercially available plant and animal wastes. Soil, grape petioles, grape leaves and grape juice were analysed over three seasons. The mulches applied released considerable quantities of nutrients, which were available for use by the grapevines. Generally, the type of mulch used had little impact on the parameters that were measured and the greatest differences occurred between non-mulched and mulch treatments. Soil pH showed an increase at three of the four sites after application of mulch. Soil phosphorus increased moderately at one site and substantially at the other three sites in the first year and soil potassium levels increased dramatically at all sites in the first year. After the application of mulches in 1999 the petiole nitrate levels increased dramatically at all sites, however there were no differences in the second year. In the third year petiole nitrate levels were again high indicating that the differences between years was probably largely attributable to differences in rainfall received among the three seasons. Petiole potassium levels also increased after the application of mulch, however the increase was nowhere near as large as the increase in soil potassium. The use of mulch increased leaf nitrogen and potassium levels but not phosphorus levels. The use of mulch did increase juice potassium, however there was greater seasonal and site variation than variation due to the effect of mulch.