Effect of rate and frequency of application of Typhula phacorrhiza on biological control of Typhula blight of creeping bentgrass

Field studies were conducted from 1985 to 1988 to determine the effect of rate and frequency of application of Typhula phacorrhiza (isolate T016) on control of Typhula blight of creeping bentgrass. In 1985 and 1986, plots of creeping bentgrass were treated with 0, 50, 100, 200, and 400 g/m2 of autoclaved grain infested with isolate T016. The increase in application rate resulted in: 1) a significant decrease in intensity of Typhula blight, 2) a reduction in time required for turfgrass to recover from injury by pathogenic species of Typhula, 3) an increase in number of sclerotia of T. phacorrhiza recovered from turfgrass thatch, and 4) a decrease in number of sclerotia of T. ishikariensis var. ishikariensis plus T. incarnata recovered from thatch. The intensity of Typhula blight, the time required for turfgrass recovery, and the number of sclerotia of T. i. ishikariensis plus T. incarnata recovered from thatch were significantly reduced in plots of creeping bentgrass that received applications of grain colonized by isolate T016 in 1985 and 1986 compared with that of plots that received applications in 1985 only. After applications of colonized grain in the fall of 1985 and 1986, in 1988 residual activity of isolate T016 was detected via a reduction in intensity of Typhula blight and an increased number of sclerotia of T. phacorrhiza recovered from thatch.