DISEASES INCIDENCE AND FUNGICIDE COST REDUCTION WITH OVERHEAD COVERED GRAPES
ABSTRACT An alternative to control diseases on the grapevine is the use of plastic overhead cover. The cost of developing a vineyard is a relevant factor in the use of plastic overhead cover and will be directly linked to the cost of pest control. The aim of this study was to establish criteria for the use of fungicides in vine plants with plastic overhead cover compared to conventional farming in order to reduce the number and cost of application. The experiment was conducted in the 2010/2011 crop year in Viamão - RS, using the Cabernet Sauvignon cultivar grafted on Paulsen 1103 in “Y Shape” trained, with 1.80 x 2.50 m spacing. The following treatments were evaluated: Treatment 1: plastic overhead cover: phytosanitary treatment applied when leaf wetting was observed; Treatment 2: plastic overhead cover: curative treatment, when there were symptoms of disease in shoots; Treatment 3: plastic overhead cover: conventional calendar treatment every 15 days, with reapplication after leaf wetting and Treatment 4: without plastic overhead cover: conventional calendar treatment every 15 days, with reapplication after leaf wetting. The lowest number of applications was observed in treatment where the criteria for fungicide applications was only when symptoms were visualized and the greater number of applications was in the area without plastic overhead cover with conventional treatment, affecting the application cost, but without reflecting in higher productivity. The highest incidence of downy mildew was observed in treatment 4. It was concluded that it is possible to reduce the number of applications and the fungicide cost for disease control using plastic overhead cover. Moreover, this management may provide less contact with chemicals during crop and reduce chemical wastes in the environment and in the harvested product.