Otimização da tecnologia de aplicação de produtos fitossanitários na cafeicultura

Abstract

Pesticides are used in coffee planting to maintain both productive capacity and grain quality. However, the coffee plant poses great challenges to the application technology, especially when it comes to spray forming. Its branches, dense foliage, and canopy’s varied size and shape prevent most of the spray to reach its targets. This thesis aims to 1) study the spray forming on coffee leaves as a result of different application rates, considering the plants’ different canopy volumes, 2) determine specific spray volume indices for coffee planting, and 3) develop and assess an Android app that provides the necessary data for correct regulation and calibration of hydropneumatic sprayers. The study was developed in two stages. In the first stage, the field activities and the laboratory activities were carried out in the Coffee Planting Sector (Gloria Experimental Farming) and in the Laboratory of Agricultural Meccanization (LAMEC), respectively, both at Universidade Federal de Uberlandia. Spray forming assays were performed in arabica coffee plots (Topázio MG 1190 and Catuaí Vermelho IAC 99 varieties) in May, July and December 2017, as different growth stages provided different leaf densities in these periods. It involved five application rates (200, 300, 400, 600, and 800 L ha-1) and three coffee canopy volumes (ranging from 8,572 to 16,200 m3 ha-1) obtained from calculating the TRV (Tree-Row Volume) for 20 plants in previously selected areas. Initially, each experiment (TRV) was analyzed separately in a randomized block design with five replications; subsequently, a combined analysis was performed in a 3 x 5 factorial design with three TRVs and five application rates. A marker with 300 g ha-1 Brilliant Blue was added into the spray for spectrophotometry. The results pointed out that the TRV and, if possible, the leaf density should be considered to define the application rate for coffee planting. It is possible to reduce the application rates of pesticides to approximately 200 L ha-1, while also increasing deposition in some operational conditions and reducing losses to the soil. Volume indices (VI) were defined for different growth stages aiming at adequate canopy wetting and reduced loss to the soil. In the second stage, an agricultural mobile app, SprayCafé, was developed for the Android platform by using the Java programming language and the IDE (Integrated Development Environment) Android Studio. The app was assessed through a questionnaire answered by 139 users, who responded to such questions as: ease of use, loading time, adequate screen resolution, relevance of data, sequence of information, and applicability. The system proved to be simple and robust, as it was assessed as adequate to the field and valuable for both technicians and coffee growers, especially for allowing safer and more appropriate pesticides applications. The graphical user interface is interactive and easy to use, requiring little technical knowledge of digital agriculture.