Optimising the effectiveness of Copper treatments for low impact viticulture

: Among all pathologies that afflict grapevine, Downy Mildew (DM) is the most important. Generally controlled by 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 generally chemicals, due to climate conditions, as well as climate changing. For this instance, Cu treatments have to be improved. Hence, the aims of this work were to determine the possibility to reduce Cu using and evaluating the variation of Cu cladding on grapevine leaves and grapes, in relation to the phytoiatric status. 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 as well and the correlation between DM 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%), although at the maximum amount of Cu, the plant protection effect was quite good. 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 to DM presence and weather. As future goals, data will be correlated with image analysis, in order to quickly study the best conditions for Cu application directly on field and having back a real time information of Cu cladding and risk classes of DM infection. In this way, it is possible to reduce inputs in plant defence and then guarantee a quality and sustainable production of grapes and wines.