Effect of Climate on Vine and Bunch Characteristics: Bunch Rot Disease Susceptibility

Christopher Steel, Dennis Greer

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14 Citations (Scopus)
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Climatic conditions of temperature, light (quantity and quality) humidity and rainfall have major impacts on vine performance, crop yield and berry quality when vines are exposed to extremes in these various climate parameters. A major climatic contrast between Eastern Australian and inland central vineyards is the day temperatures are significantly higher at the inland vineyards (35'42°C) whereas relative humidities are higher at the eastern vineyards (30 cf. 80% RH). This difference in climate causes a high predisposition of grapes to non-Botrytis bunch rots, most notably bitter rot (Greeneria uvicola) and ripe rot (Colletotrichum acutatum), in the wetter eastern sites and little to no infection on vines in the inland vineyards. By contrast, high light exposures, coupled with extremely hot (>35°C) temperatures at inland vineyards cause severe skin damage in the form of sunburn. Sunburn damage does, however, increase the incidence of Botrytis latent infections in grapes. In both cases bunch rots and skin damage causes a loss of berry quality and has severe impacts on wine quality. Management practices include maintaining open canopies for Botrytis control; however, this has the downside of increasing non-Botrytis bunch rot infections. A greater effect of this practice on west compared to east-facing rows suggests combinations of sunburn and/or heat stress or even higher UV-B (280'320 nm) may explain the exacerbation in non-Botrytis bunch rot incidence. While exposure to UV-C (<280 nm) elicits formation antifungal metabolites in vine tissues, this effect is not seen with UV-B which may in fact encourage bunch rots. Future climate changes that lead to increased wetness in the inland wine grape regions of Australia will be detrimental in bringing higher incidences of bunch rots and reducing the competitive advantage in grape growing that these regions currently enjoy.
Original languageEnglish
Pages (from-to)253-262
Number of pages10
JournalActa Horticulturae
Issue number785
Publication statusPublished - 2008

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