An IPM approach to isopod control in no-till soybean

The benefits of no-till or reduced tillage practices have been well demonstrated. Unfortunately, significant changes in an agroecosystem may promote unanticipated pest problems. For example, moist microhabitats created by increased crop residue on no-till fields may provide the protection necessary for background organisms to reach pest status. In recent years, pillbugs and sowbugs (Malacostraca: Isopoda) have become a recurrent, early-season problem throughout reduced and no- till production soybean fields in south central Kansas. The succulent stem tissue below the cotyledons of germinating soybean seedlings is susceptible to isopod herbivory. This type of damage results in the compete destruction of the growing plant. Under intense isopod pressure, soybean growers must replant fields multiple times to establish a harvestable stand. Effective integrated pest management (IPM) strategies for isopod damage in soybean are not known. The objectives of this study were to 1) evaluate potential control tactics for reducing isopod damage and 2) develop a research-based sampling unit and plan for quantifying isopod populations in no-till soybean. Several field experiments were conducted to determine the effects of various control strategies (i.e., residue destruction, planting date, insecticide rate and seeding rate) on the emergence of soybean in no-till production fields with a history of isopod damage near Lindsborg, KS. Companion studies were conducted in the greenhouse to corroborate findings from field experiments. In general, residue removal was most effective at controlling isopod damage. Development of a research-based sampling plan and selection of a sampling unit will be discussed.