Efficacy of Typhula phacorrhiza as a biocontrol agent of grey snow mould of creeping bentgrass

Isolates of the fungus Typhula phacorrhiza Fries (TP) were evaluated in fie ld tests over a 3-year period for suppression of grey snow mould caused by Typhula ishikariensis Imai (Tish) and Typhula incarnata Lasch ex Fr. (Tinc) . Isolates of TP were collected across southern Ontario in the spring of 19 94. In December 1994, 46 of these isolates, which had been cultured on mixe d grains, were applied to creeping bent grass (Agrostis stolonifera L.) at a rate of 200 g/m(2) (4 x 10(5) colony forming units (cfu)/m(2)) with inocu lum of Tish or Tinc at 10 g/m(2) (2 x 10(4) cfu/m(2)). In December 1995, 30 selected TP isolates were inoculated onto a new set of plots along with gr ey snow mould fungi. In November 1996, 22 of these isolates were re-inocula ted onto the 1995 plots. All plots were rated for injury after snowmelt, 19 95-1997. Isolates of TP varied significantly in their ability to suppress d isease. No strong correlations were found between in vitro growth character istics and field performance; however, significant positive correlations we re found between the disease suppression trials for the 3 years, with sever al isolates showing statistically significant control of grey snow mould eq ual to a fungicide treatment.