Drops spectra and leaflets age on the fungicides absorption rate and residual effect in soybean/Espectro de gotas e idade de trifolios na taxa de absorcao e efeito residual de fungicidas em soja

• Published in: Ciência rural 2011-10, Vol.41 (10), p.1702
• Main Authors: Lenz, Giuvan, Balardin, Ricardo Silveiro, Minuzzi, Simone Gripa, Tormen, Nedio Rodrigo, Marques, Leandro Nascimento
• Format: Article
• Language: Spanish
• Subjects: Fungicides; Soybeans; Triazoles
• ISSN: 0103-8478

This research aimed to evaluate the effect of large, medium and fine droplets spectra and its interaction with the fungicide absorption rate and leaflets age through indirect measurement expressed by the residual control of Asian soybean rust (Phakopsora pachyrhizi). The experimental design was completely randomized with four replications in a factorial scheme (3x3x5x4), which factors were composed of: three drops spectra (large, medium and fine); three different positions in the plant evaluated (1st, 3rd and 5th leaflets), four time periods between the fungicide application and simulated rain (0, 30, 60 and 120') and a control with no rain; control without fungicide application, Azoxystrobin+Cyproconazole (60+24g a.i. [ha.sup.-1]) + 0.6L [ha.sup.-1], Azoxystrobin (50g a.i. [ha.sup.-1]) + 0.6L [ha.sup.-1] and Cyproconazole (30g a.i. [ha.sup.-1]). It was evaluated the density of droplets per square centimeter, volume median diameter, number median diameter and relative amplitude, and the number of days for the first pustule display. It was found that drops with smaller volume median diameter have higher fungicides absorption rates. Newer leaflets provide more quickly fungicides absorption. The use of Azoxystrobin + Cyproconazole provided the greatest number of days until the appearance of the first pustule. Key words: Phakopsora pachyrhizi, spray technology, strobilurin, triazole, simulated rain, residual. O objetivo do presente trabalho foi avaliar o efeito de espectros de gotas (grossas, medias e finas) na velocidade de absorcao de fungicidas, para trifolios de diferentes idades atraves de medida indireta expressa pelo residual de controle de ferrugem asiatica da soja (Phakopsora pachyrhizi). O delineamento experimental utilizado foi inteiramente casualizado, com quatro repeticoes, em arranjo fatorial (3x3x5x4), cujos fatores foram compostos por: tres categorias de gotas (grossas, medias e finas); tres diferentes posicoes de avaliacao na planta (1, 3 e 5 trifolios); quatro periodos de tempo entre a aplicacao de fungicidas e aplicacao de chuva simulada (0, 30, 60 e 120min), mais uma testemunha sem chuva; testemunha sem aplicacao, mais os fungicidas azoxistrobina + ciproconazol (60+24g i.a. [ha.sup.-1]) + oleo mineral 0,6L [ha.sup.-1]), azoxistrobina (50g i.a. [ha.sup.-1]) + oleo mineral 0,6L hae ciproconazol (30g i.a. [ha.sup.-1]). Avaliou-se a densidade de gotas por centimetro quadrado, diametro mediano volumetrico, diametro mediano numerico e amplitude r