VIEW ARTICLE

A Modified Soil-Over-Culture Method for Inducing Basidia in Thanatephorus cucumeris. C. C. Tu, Department of Botany, University of Florida, Gainesville, 32611, Present address of senior author: Tainan Fiber Crops Experiment Station, Tainan, Taiwan, Republic of China; James W. Kimbrough, Department of Botany, University of Florida, Gainesville, 32611. Phytopathology 65:730-731. DOI: 10.1094/Phyto-65-730.

In the induction of basidia by Rhizoctonia solani with the soil-over-culture method, dextrose and yeast extract were the major components of the primary medium. Tests were performed to determine the optimum concentrations of these components for basidial production. Experiments with soil pH, soil moisture, soil compaction, and mycelium age at the time of overlay were designed to study the effects of those variables on sporulation. The following soil-over-culture method is proposed: (i) inoculate the fungus to 20 ml of yeast extract-dextrose agar in 9 cm petri dishes, (ii) incubate at room temperature until the fungus colony covers the agar surface or up to 2 days later, (iii) cover the agar surface with 90 g of oven dry soil (silty clay) to make a soil layer approximately 1 cm deep, (iv) adjust the soil reaction to pH 8-9, (v) maintain the soil moisture at 30% (by weight), and (vi) incubate at room conditions.