THE EFFECT OF BIOACTIVE COMPOUNDS ON SOYBEAN RUST CONTROL

Soybean Rust (SR), caused by the fungus Phakopsora pachyrhizi is the main disease that affects soybean crop, causing great damage during culture and yield. Currently the control is made from pesticides, however, the continuous use of these products select resistant fungi, and also contaminating soils and water. In this context, natural products mainly bioactive extracted from the secondary metabolism of microorganisms, have been studied and test its applications to evaluate the activity on soybean rust control. Pseudomonas are known as producer of secondary metabolites with antimicrobial properties, which can be used in the combat of phytopathogens, such as the fungus that causes SR. The present paper proposed to evaluate the use of the F4A bioproduct, extracted from the secondary metabolism of the P. aeruginosa LV strain, to control SR associated or not with commercial fungicidades. The experiment was carried out in a fieldconditions, and was considered control the fungicides Mancozebe (Unizeb Gold®) and Trifloxystrobin + Ciproconazol (Sphere Max®).The experiment was carried out at the UEL School Farm and the experimental design was seven treatments: Unizeb Gold + Sphere Max (Uni + Sph); F4A 1 μg mL-1 (F4A1); F4A 1 μg mL-1 + Unizeb Gold (F4A1 + Uni); F4A 1 μg mL-1 + Sphere Max (F4A1 + Sph); F4A 10 μg mL-1 (F4A10); F4A 10 μg mL-1 + Unizeb Gold (F4A10 + Uni); F4A 10 μg mL-1 + Sphere Max (F4A10 + Sph), distributed in a randomized block design, with 5 replicates. Three applications were performed in each treatment. The average severity of the plots (foliar area covered with symptoms) was estimated weekly since the first application of the products, with the aid of the diagrammatic scale, where the Area Under the Disease Progress Curve (AADPC) was estimated. The results showed that both concentrations of F4A fraction did not show any difference when compared with commercial products, when F4A was associated with Sphere Max, moreover, as regards productivity, it was observed that the plants treated with F4A1 reached productivity values close to those obtained in the control group. The F4A fraction showed great potential to use in the control of SR, especially when was associated with Sphere Max in both doses used.