Ocorrência E Intensidade De Doenças Foliares E Ciclo De Cultivo Em Seis Cultivares De Soja Durante Duas Épocas De Semeadura

Abstract

A randomized complete block design (DBCA) with six treatments and four replications was used, and the data obtained were submitted to variance analysis. Subsequently, a comparison of media by Tukey (p≤0.05) was carried out for each season, and for the comparison between the seasons test T (p≤0.05) was used. The intensity of leaf diseases present in the aerial part of crop was evaluated weekly in a period of five weeks. Severity values (except cercospora blight and soybean rust) were integrated in the area under the relative disease progress curve (AACPDr). Cultivars A 4910 RG and BMX Apolo RR had lower severity of downy mildew and blight cercospora, as well as of the number of lesions cm -2 of Asian rust. Cultivars CD 219 RR and FUNDACEP 55 RR showed less bacterial blight, downy mildew and powdery mildew severity. Genotype A 4910 RG behaved as very early, BMX Apolo RR, A 6001 RR and CD 214 RR as precocious, FUNDACEP RR 55 as medium and CD 219 RR as late.

Chemical control of foliar diseases in soybean depends on cultivar and sowing date

“…Five cultivars of different cycles (DE ALMEIDA et al, 2014) ), in three moments 1: pre-closure of the space between the lines and 21 days after; 2: pre-closure of space between rows and R5.1 stage (10% of beginning seed); and 3: R1 (beginning bloom) and R5.1 stages. The volume of broth used in all applications was 200 L ha -1 , with spray tip TJ60 11002 (100), using a CO 2 pressurized spray, calibrated at a pressure of 2 bar.…”

“…Asian rust intensity is directly influenced by the frequency of rainfall over the crop cycle (DEL PONTE et al, 2006). However, powdery mildew has been more intense in this region of the country in recent seasons due to low rainfall (DE ALMEIDA et al, 2014). In susceptible cultivars, both Asian Rust and powdery mildew may originate yield losses between 35 and 90%, respectively (HARTMAN et al, 1999).…”

“…These predisposing conditions in the no-tillage crop environment are related to the sowing time, due to the temperature and wetting conditions of each period (DE ALMEIDA et al, 2014).…”