Drechslera sp. (Pyrenophora chaetomioides (Speg.)), a Potential Biocontrol Agent for Bromus sterilis and Other Bromus spp.

Infection by a Drechslera sp. (perfect stage, Pyrenophora chaetomioides (Speg.)), isolated from Bromus sterilis , killed B. sterilis , B. commutatus and B. secalinus. B. diandrus and B. hordeaceus were both infected but not killed. Successful infection required a 24-h dew period. Reduction of the dew period to 8 h significantly reduced the infection of all Bromus spp. tested as determined by leaf necrosis. Inoculation with a low inoculum concentration (2 104 conidia/ml) produced little dry weight reduction, but at 2 105 conidia/ml with an 8-h dew period the dry weights of B. commutatus , B. diandrus , B. secalinus and B. sterilis were reduced by 11-25%. Extending the dew period to 24 h resulted in 77% mortality of B. sterilis and 93% mortality of B. commutatus and B. secalinus.