Study to optimize the effectiveness of copper treatments for low impact viticulture

Abstract

Among all pathologies that afflict grapevine, Downy Mildew (DM) is the most important. Generally controlled using Copper (Cu), recently European Commission confirmed its usage but limiting the maximum amount to 28 Kg per hectare in 7 years (Reg. EU 2018/1981). Anyway, in the grape growing context it is difficult to reduce the use of Cu and chemicals, due to climate conditions.

The aim of this work was to determine the possibility to reduce Cu using and evaluating the variation of Cu cladding on grapevine leaves and grapes, in relation to climatic conditions. The efficacy level of the Cu protection given to DM and the correlation among them was also assessed. 

Five organic vineyards located in north-eastern of Italy were selected as experimental sites. Leaves and grapes were sampled during vegetative season and analysed for determining the quantity of elemental Cu by the use of ICP AES. Spreading of DM in vineyards was evaluated and climate data (rainfall, temperature and leaf wetness) measured. The correlation between DM, climate and Cu quantity on leaves and grapes was determined. First results indicate that the mean level of Cu applied by farmers (range: 3.77 to 8.88 µg/cm2 of Cu on leaves) during vegetative season is not enough to have an optimal protection against DM (diffusion on grapes and leaves: 40 to 50%). Thus, Cu treatments have to be pondered on the basis of meteorological data and previous infection of DM, so that it will be possible to determine the right quantity of Cu to be applied in correlation with DM presence and weather. 

Data will be correlated with image analysis, in order to quickly study the best conditions for Cu application directly on field, to reduce inputs in plant defence and to guarantee a quality and sustainable production.