Pilot Insect Pest Management Program for Soybean in Southern Brazil1

During the 1974–75 soybean growing season, a pilot pest management program was tested in Southern Brazil. Nine paired field locations, varying in size from 10–30 ha, were selected in commercial farms for this experiment. One field of the pair was managed by following a simple pest management strategy and the other field by following farmers own criteria. The strategy consisted of scouting fields once a week to monitor populations of defoliating lepidopterous caterpillars and pod sucking stink bugs which were the target insect pests. Damage thresholds and treatment decisions were based on assessment of defoliation levels, pest populations, and presence of pathogens, mainly the fungus Nomuraea rileyi (Farlow) Samson. Minimal dosages of nonpersistent pesticides were prescribed in fields reaching damage thresholds. Although treatment decisions by farmers probably were influenced by the pest management program, they made a total of 9 treatments (avg one/field) as opposed to only 2 treatments made in the pest management fields, a reduction of 78% in the number of insecticide applications in the experimental program. The program was repeated in 1976 and was officially recommended by the state of Parana (2nd largest producer in Brazil). In 1977, a similar program was adopted on a national scale. The program allowed us to test under normal field conditions some parameters of soybean pest management systems developed in the United States. It demonstrated that simple scouting procedures and adequate economic damage thresholds can be used in preliminary pest management strategies even if phenology and population dynamics of key pests are incompletely known.