A simple Pythium aphanidermatum field inoculation technique for perennial ryegrass

Abstract

A simple field Pythium inoculation technique is needed to be able to assess cultivars for disease resistance and effectiveness of cultural practices or fungicides in the management of Pythium blight. We assessed two mixtures as inocula [i.e, an infested tall rescue (Festuca arundinacea Schreb.) seed plus wheat (Triticum aestivum L.) bran and an infested rye (Secale cereale L.) plus barley (Hordeum vulgare L.) grain mix], and three covers (black and clear plastic, and a geothermal blanket) for their ease of use and consistency in producing Pythium blight epidemics in perennial ryegrass (Lolium perenne L.) field plots. Both the rescue seed-wheat bran and rye-barley grain inocula provided good media on which to culture Pythium aphanidermatum (Edson) Fitzp. In general, the fescue-wheat bran mix applied at the high level (100 mL/0.9-m2 plots) produced greater blight ratings in perennial ryegrass than did the low level (50 mL/0.9-m2 plot). The fescue-wheat bran also was generally more effective than either rate of the rye-barley mix in blighting turf. All covers enhanced blighting, when compared to the uncovered control, by raising the relative humidity. Covering plots with black plastic following inoculation resulted in greater blight ratings than did covering with either clear plastic or the geothermal blanket.