In this project's first year of field testing, conducted from October 2011 to October 2012, Contans was most effective when applied in October, shortly after harvest of the previous crop and 7 months prior to planting soybeans. Relative to the non-treated control, applications of Contans made on October 11, 2011 reduced apothecia production by 79% and reduced the viability of sclerotia by 59% in the subsequent soybean crop, and applications of Contans made on April 24, 2012 reduced apothecia production by 50% and reduced the viability of sclerotia by 17%.
Application timing in the spring had no effect on the efficacy of Contans; applications of Contans made on April 3, April 10, April 17, April 24, May 1, and May 9 performed nearly identically. Contans performed similarly when applied at 1 lb./ac and 2 lb./ac, suggesting that the lower application rate may be sufficient. Manual incorporation (a light harrowing) of Contans performed similarly to water incorporation (1 inch applied through a pivot). Sclerotia were primarily on the soil surface in this experiment. Testing is currently in progress to evaluate optimal application rates and incorporation methods for Contans when sclerotia are evenly distributed throughout the top few inches of the soil, (as occurs in most conventionally tilled fields).