Control of leaf diseases in wheat with low spray volume equipments/Controle de doencas foliares em trigo com equipamentos de pulverizacao de baixo volume de aplicacao

The use of spraying equipments with lower spray volume at disease control is a tendency in agriculture. The study aimed to determinate the efficiency of low spray volume at the wheat leaf diseases control. The experiment was carried during two harvest years and three cultivars in Santa Maria, RS. The treatments were constituted of different spraying equipments: hydraulic nozzle (XR 110015) and hollow cone (TX-VK6), both with spray volume of 120L [ha.sup.-1], rotary-disk atomizer using low volume in oil, with spray volume of 24L [ha.sup.-1] and 34L [ha.sup.-1] and a control treatment without application. The droplets generated by the equipments (density, medium volumetric diameter) were evaluated throughout the use of water sensible cards. Also were evaluated the yellow leaf blight and leaf rust. The use of hydraulic nozzle at spray volume of 120L [ha.sup.-1] showed higher efficiency on the disease control. The rotary-disk atomizer with spray volume of 34L [ha.sup.-1] showed similar efficiency in the disease control of hydraulic nozzle. The droplet density was superior to 40 droplets [cm.sup.-2] in all treatments, also at the rotary-disk treatments with low pulverization rates. The disease control did not show direct relation with the coverage measured by the water sensible cards.