BEHAVIOR OF SYSTEMIC FUNGICIDES TO CONTROL ASIAN RUST IN SOY

Abstract

ASIAN SOYBEAN RUST CAUSED BY THE FUNGUS PHAKOPSORA PACHYRHIZI SYD. & SYD., IS THE MAJOR DISEASE AFFECTING THE CROP, CAUSING MUCH DAMAGE TO GRAIN YIELD. THE STRATEGY USED IN BRAZIL SINCE THE CONTROL OF THIS DISEASE IS THE APPLICATION OF FUNGICIDES. THUS, THE OBJECTIVE WAS TO EVALUATE THE EFFICIENCY OF FUNGICIDES FROM SPECIFIC (SYSTEMIC) SITES ON THE PROGRESS AND CONTROL OF ASIAN SOYBEAN RUST (FAS), AS WELL AS ITS EFFECT ON CROP YIELD IN 2018/19 CROPS. THE WORK WAS CARRIED OUT IN AN EXPERIMENTAL FIELD AT FAZENDA VERA CRUZ AGROPECU�RIA LTDA. THE SOYBEAN CULTIVAR BMX CERTA IPRO WAS USED. THE EXPERIMENTAL DESIGN WAS A RANDOMIZED BLOCK DESIGN (DBC) WITH 12 TREATMENTS AND FOUR REPLICATIONS, TOTALING 48 PLOTS. PERCENTAGE SEVERITY ASSESSMENTS WERE MADE WITH THE AID OF THE FAS DIAGRAMMATIC SEVERITY SCALE OF GODOY ET AL. (2006), DURING THE WHOLE CYCLE IN DIFFERENT DATES AND STAGES OF CULTURE, A TOTAL OF 6 EVALUATIONS WERE CARRIED OUT, THE FIRST ONE AT STAGE V4 AND THE LAST 42 DAYS AFTER R1. PLANT HEIGHT, ONE THOUSAND GRAIN WEIGHT AND YIELD WERE ALSO DETERMINED AT HARVEST. IN THE PLANT HEIGHT EVALUATION NONE OF THE FUNGICIDE TREATMENTS WAS SUPERIOR TO THE CONTROL, PRESENTING THE SAME OR EVEN INFERIOR RESULTS IN SOME CASES. FOR THE WEIGHT EVALUATION OF ONE THOUSAND GRAINS, MOST FUNGICIDE TREATMENTS WERE SUPERIOR TO CONTROL EXCEPT FOR APROACH PRIMA, SPHERE MAX AND ORKESTRA SC WHICH DID NOT DIFFER STATISTICALLY FROM THE CONTROL. ALL FUNGICIDES TESTED WERE EFFECTIVE IN CONTROLLING THE DISEASE WITH AACPD VALUES �€‹�€‹BELOW CONTROL.