Drops spectra and leaflets age and its interaction with the area under disease progress curve of soybean rust/Espectros de gotas e idade de trifolios e sua interacao com a area abaixo da curva de progresso da ferrugem da soja

• Published in: Ciência rural 2012-09, Vol.42 (9), p.1528
• Main Authors: Lenz, Giuvan, Balardin, Ricardo Silveiro, Minuzzi, Simone Gripa, Madalosso, Marcelo, Debortoli, Monica, Gulart, Caroline, de Ramos, Juliano Perlin
• 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 of Asian soybean rust (Phakopsora pachyrhizi) control. The experimental design was composed by completely randomized design with four replications in a factorial (3x3x5x4), which factors were composed of: three drops spectra (large, medium and fine); three fisiological leaflets ages setting on the plant (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; three fungicide treatments with Azoxystrobin+Cyproconazole (60+24g ad. [ha.sup.-1]) + 0.6L [ha.sup.-1], Azoxystrobin (50g ad. [ha.sup.-1]) + 0.6L [ha.sup.-1] and Cyproconazole (30g a.i. [ha.sup.-1]), and control without spray. It were evaluated the density of droplets per square centimeter, volume median diameter, number median diameter, relative amplitude, number of days for the first pustule display and the area under disease progress curve. 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 lower disease progress with consequent lower area under the disease progress curve.