Atividade de inseticidas em diferentes modalidades de aplicação no controle de insetos vetores de viroses na cultura da alface (Lactuca sativa L.)

Abstract

The culture of lettuce (Lactuca sativa L.) is one of the most used vegetables in human food, being cultivated all over Brazil. Like most vegetables, lettuce is also subject to pests and diseases attack, requiring the producer the appropriate phytosanitary management. One of the most common diseases is the "vira-cabeça", which has as vector the thrips, Frankliniella occidentalis (Pergande), F. schultzei (Trybom), small insect of the order Thysanoptera and of national occurrence, causing significant losses in the Summer and at the young phase of the plant. Together with the thrips, another common pest is the greenfly Myzus persicae (Sulzer), leaf sap sucking aphid and lettuce mosaic transmitter (LMV). The objective of this work was to evaluate the activity of phytosanitary products applied in the treatment of seedlings (vaccination) and spraying, in the control of tripes (F. occidentalis) and of the aphid M. persicae and its effect on the development of lettuce plants in field cultivation. The experiment was carried out in the olericulture sector of the Campus Glória’s Farm (Federal University of Uberlândia), and eight treatments with four replications were used, combining applications through treatment of seedlings complemented with leaf spraying, being 1. Witness without application; 2. Actara 250 WG (300 g / ha) in seedling treatment; 3. Evidence 700 WG (300 g / ha) in seedling treatment; 4. Calypso (20 mL / 100 L of water) sprayed; 5. Provided 200 SC (70 mL / 100 L water) sprayed; 6. Azamax (250 mL / 100 L water) sprayed; 7. Actara 250 WG (300 g / ha) in seedling treatment + Chess 500 WG (50 g / 100 L of water) sprayed; 8. Actara 250 WG (300 g / ha) in seedling treatment + Azamax (250 mL / 100 L of water) sprayed. The insecticides used in treatment of seedlings were applied with a hand sprayer one day before transplanting, with a volume of 400 ml of syrup per tray and the sprays performed at 7 and 14 days after transplanting using a manual sprayer with volume of syrup of 500 L / ha. Weekly evaluations were carried out, counting the number of aphids and thrips in five plants per plot. In addition to the insect count, plant development evaluations were performed by assigning development notes. At 49 days after transplanting, five plants were harvested per plot. The combination of the treatment of seedlings with foliar sprays provided better control of the pests, besides promoting greater strength and development of the plants. All treatments were efficient in the control of thrips and aphid. As for the development of plants, all treatments provided better development and increased productivity.