Mycelial growth, sclerotial production and carbon utilization of three Typhula species

The mycelial growth, sclerotial production, and carbon utilization of the snow mould biocontrol agent Typhula phacorrhiza Fries were compared with the two grey snow mould fungi, Typhula ishikariensis Imai and Typhula incarnata Lasch ex Fries. Variation was observed among the four isolates for each species, but there was greater variation among species. All three species were able to grow at the lowest temperature (0°C), but temperature optima differed with T. ishikariensis lowest and T. phacorrhiza highest. On potato dextrose agar or potato malt agar at 10°C, T. phacorrhiza had greater radial growth than T. ishikariensis but less than T. incarnata. All species could utilize microcrystalline cellulose, bacto-cellulose, and glucose as carbon sources, but radial growth of T. phacorrhiza was significantly greater than T. incarnata and T. ishikariensis on these defined carbon sources tested, except for IndulinAT, which was inhibitory to T. incarnata and T. phacorrhiza. This greater ability to utilize these structural and storage carbohydrates, combined with mycelial growth and sclerotial production over a wider range of temperatures, may help explain how some isolates of T. phacorrhiza are able to outcompete grey snow mould in field tests.