Copper reduction strategy for sangiovese in organic viticulture

Abstract

Organic viticulture requires copper based treatments for bunch protection even though an intensive employment is no longer admitted because of its low leaching and phytotoxicity in the soil. UE Reg. 1981/2018 set copper employment to 4 kg/ha for year or 28 during 7 years with an absolute level allowed of 6 Kg/ha although those limits were decreased frequently. In order to reduce copper a valid strategy is to monitor vineyard microclimate (wind, temperature, humidity) implementing DSS to maximize treatments effectiveness. We can also stimulate plant natural defenses by supporting substances (Biostimulants, Inductors, Revitalizing molecules) in order to minimize number of treatments. In the Castello of Gabbiano farm (DOCG Chianti Classico, Italy) during 2019 and 2020, an organic management has been compared with the same organic management but with reduced treatments and adding supporting substances to the grapevine, over 3 vineyards with different exposition and slope. No statistical significance (P>0,05) has been found between the two managements inside each vineyard regarding grapes production and quality. Downy mildew Incidence and severity on leaf and bunch were higher in the low copper employment management only in 2020. Data of copper treatments allowed a calculation of 2.7 kg/ha and 4.3 copper employment for organic and low treatments organic management respectively over the two years, producing grapevine with the same quality but with a copper distribution reduction of 37-40% over different exposition and cultivation situations.