Tillage and rotation effects on Collembola populations and Rhizoctonia infestation

The use of Collembola as a biocontrol for Rhizoctonia solani has been suggested and the role of these mycophagous insects ion rhizosphere ecology is being investigated. The purpose of this study was monitor Collembola populations and Rhizoctonia infestation throughout the growing season as they were affected by crop management practices. The study was conducted on a Decatur silt loam (Rhodic Paleuult) and a Dothan sandy loam (Plinthic paleudult) and included 7 sample date through the 1985 summer season. Crop-production treatments consisted of tillage (till and no-till) and crop species (corn, cotton, peanut and soybean). Insect numbers were similar between soil types, but sample date and management practices resulted in significant differences, and interactions with soil type occurred. Populations peaked at mid-season in the Decatur silt loam and during early and late sample dates in the Dothan sandy loam. At both locations, soil moisture at time of maximum Collembola and number was approximately 11%. Levels of Rhizoctonia were greater in the sandy loam silt loam silt loam and generally greater during mid-season than early or late samples. No-till resulted in 29% more Collembola than conventional tillage. Corn producing soils contained 72, 47 and 41% more Collembola than soils producing soybeans, cotton and peanuts, respectively. Generally, differences in pathogen and insect levels were greter among sample dates than between crop management practices.