Interaction spray nozzle-adjuvant to estimate potential risk of spray drift/ Interacao pontas-adjuvantes na estimativa do risco potencial de deriva de pulverizacoes

There is increasing concern about the risk of pesticide spray drift and their effects on the environment, becoming increasingly important to use spray technologies that provide greater security. This study aimed to evaluate flat angled fan nozzle and the air induction flat fan nozzle combined to different spray adjuvant for agricultural use to estimate the potential risk of spray drift through deposits and spectrum of drops. The treatments were four spray solutions combined with two spray nozzles. Spray deposits were measured at different distances and heights into a wind tunnel. Indicators of droplet spectrum were: percentage of droplets volume smaller than or equal to 100 µm of diameter, volume median diameter (VMD), and relative span factor, obtained in a laser particle analyser. The addition of vegetal polymer adjuvant to water resulted in lower levels of spray deposits, reducing the percentage of droplets volume smaller than or equal to 100 µm of diameter and showed larger VMD, indicating low potential risk of spray drift. Higher deposit levels were obtained under angled flat fan nozzle without addition of adjuvant to the spray solution, which represents a greater potential risk of spray drift.