Host water potentials may restrict development of snow mould fungi in low temperature‐hardened grasses

Abstract

The growth of the snow mould fungi Fusarium nivale (Fr.) Ces. and Typhula ishikariensis Imai at different water potentials was measured on potato dextrose broth supplemented with KCl or polyethylene glycol 6000. The dew point hygrometer method was used for determination of water potentials in both artificial growth media and plant material. Both fungi had a considerable decrease in dry weight production when water potentials of growth media were decreased from −0.7 to −3 MPa. Crown tissue from hardened plants of Phleum pratense L. (timothy, cvs Engmo, Grindstad) and Phalaris arundinacea L. (reed canary grass, cvs Hansvoll, American common, Vantage) showed a significant decrease in water potentials compared with unhardened plants. Thus, reduced availability of water may partly explain increased resistance to fungal pathogens in grasses after hardening.