Espectro de gotas de pulverização e controle da ferrugem-asiática-da-soja em cultivares com diferentes arquiteturas de planta

Abstract

Resumo -O objetivo deste trabalho foi determinar o espectro de gotas de pulverização ideal para o controle da ferrugem-asiática-da-soja (Phakopsora pachyrhizi), em cultivares com diferentes arquiteturas de planta. O experimento foi conduzido na safra de 2009/2010. A aplicação de fungicida (piraclostrobina + epoxiconazol, com óleo mineral) foi avaliada com quatro espectros de gotas de pulverização -muito fino, <119 µm; fino, 119 a 216 µm; médio, 217 a 352 µm; e grosso, 353 a 464 µm -, em quatro cultivares de soja (BMX Apollo RR, NA 7636 RR, Fcep 53 RR e TMG 4001 RR) contrastantes quanto a índice de área foliar, estatura de plantas e número de ramos por planta. Foram quantificadas as variáveis: número de gotas por cm 2 , diâmetro mediano volumétrico das gotas, área abaixo da curva de progresso da ferrugem-asiática e produtividade da soja. A definição do espectro de gotas a ser utilizado deve considerar a cultivar e as condições ambientais em que a pulverização será realizada. A magnitude da proteção exercida pelo fungicida varia de acordo com a cobertura de plantas e a penetração de gotas no dossel, proporcionada pelos diferentes espectros de gota. O espectro de gotas fino proporciona boa deposição de gotas, controle da doença e produtividade, independentemente da cultivar avaliada.Termos para indexação: Phakopsora pachyrhizi, cobertura de plantas, controle químico, deposição de gotas, penetração no dossel, tecnologia de aplicação. Spray droplet spectrum and control of Asian soybean rust in cultivars with different plant architectureAbstract -The objective of this work was to determine the ideal spray droplet spectrum for the control of Asian soybean rust (Phakopsora pachyrhizi), in cultivars with different plant architecture. The experiment was carried out in the 2009/2010 crop season. Fungicide application (pyraclostrobin + epoxyconazole, with mineral oil) was evaluated with four spray droplet spectra -very fine, <119 µm; fine, 119 to 216 µm; medium, 217 to 352 µm; and coarse, 353 to 464 µm -in four soybean cultivars (BMX Apollo RR, NA 7636 RR, Fcep 53 RR, and TMG 4001 RR) contrasting as to leaf area index, plant height, and number of branches per plant. The following variables were quantified: number of drops per cm 2 , median volume diameter of droplets, area under the progress curve of soybean rust, and soybean yield. The definition of the droplet spectrum to be used should consider cultivar and environmental conditions in which the pulverization will be done. The protection magnitude exerted by the fungicide varies according to the plant coverage and the penetration of droplets into the canopy provided by the different droplet spectra. The fine droplet spectrum provides good droplet deposition, disease control, and productivity, regardless of the evaluated cultivar.

Spraying systems and traveling speed in the deposit and spectrum of droplets in cotton plant

“…At the apex of the plant leaf, abaxial surface, and at the base of the plant in both leaf surfaces, the use of centrifugal tips provided deposits on average 4.59 times higher than those obtained with hydraulic tips. According to DEBORTOLI et al (2012) the highest amounts of deposits obtained from the lower parts of the crop canopy indicate potential advantages for use of the rotating nozzle in the control of biological targets located therein.…”

Fungicide application using a trailing boom in soybean fields

“…It is possible to obtain a penetration of the drops in crop canopy changing spray tips, droplet size and spray volume when spraying fungicide on soybeans (MATTHEWS, 2008;DEBORTOLI, et al, 2012). However, CUNHA et al (2008); NASCIMENTO et al (2009) andROMAN et al (2009) found no significant differences in the chemical control of foliar diseases of soybean spray volumes above 100L ha -1 when evaluating those hypotheses.…”

Droplet spectrum and fungicide efficiency in the control of Asian soybean rust (Phakopsora pachyrhizi Syd. & P. Syd.)

“…The droplet spectrum is important during fungicide application, due to closure of soybean leaf cover throughout the crop. In this regard, fine droplet spectrum provides an efficient deposition, control of the Asian soybean rust, and productivity, regardless of the soybean cultivar assessed (Debortoli et al, 2012). Such droplets have a higher fungicide absorption rate (Lenz, Balardin, Minuzzi, Tormen & Marques, 2011), and higher penetration on soybean plant canopy (Román, Cortez, Ferreira & Oliveira, 2009).…”

“…Spray tips are the most important components of sprayers according to Sidahmed (1998), existing currently on the market a great variety with different technical and operational characteristics. Generally, tips that produce fine droplets, such as standard flatjet tips are used (Debortoli, Tormen, Balardin, Favera, Stefanello, Pinto & Uebel, 2012). Owing to the fact that the droplet spectrum usually drifts, tips that produce larger droplets with air induction are preferred (Cunha, & Ruas 2006).…”

“…Owing to the fact that the droplet spectrum usually drifts, tips that produce larger droplets with air induction are preferred (Cunha, & Ruas 2006). However, establishing a droplet spectrum that will be used for a certain crop must consider its cultivation and environmental conditions in which pulverization or spraying will be carried out (Debortoli et al, 2012). Furthermore, other parameters as leaf area index (LAI) in soybean cultivars may influence droplet deposition and penetration into its canopy .…”