A preliminary evaluation of the rice blast fungus (Magnaporthe grisea) as a potential bioherbicide control agent for crabgrass (Digitaria sanguinalis) infestations of tall fescue (Festuca arundinacea Schreb. cv. Fawn) turf

This study addressed the possibility of rice blast fungus (Magnaporthe grisea) as a potential bioherbicide for the control of crabgrass (Digitaria sanguinalis), in turf/lawn plantings. Experiments were: (i) evaluation of the effect of bioherbicide inoculum dosage (titer) on disease severity in crabgrass; (ii) competition between crabgrass and tall fescue (Festuca agrundinacea Schreb. 'Fawn') and the additive effect of rice blast bioherbicide on the competitiveness of crabgrass; (iii) survival of rice blast spores under non-conducive infection conditions on crabgrass; and (iv) effect of multiple inoculations of rice blast fungus and subsequent disease on crabgrass.;Spore concentrations of 5 ;Competition studies indicated crabgrass will out-compete fescue 'Fawn' in plots of equal numbers of each plant, i.e., 3 fescue and 3 crabgrass. In 10 ;Survival of Magnaporthe grisea conidia under non-conducive conditions was tested by drying inoculated crabgrass seedlings for 0-48 hours prior to dew-deposition. Treatments verified spores remain viable at least 24 hours on crabgrass leaves under greenhouse conditions (25-40;Two successive inoculations (at 3 days and 7 days after primary inoculation) of crabgrass with M. grisea conidia (5 ;Results suggested Magnaporthe grisea exhibits potential for future development as a commercial bioherbicide to control crabgrass (Digitaria sanguinalis). Current studies investigated integration in lawn grass, but should be applicable to situations anywhere crabgrass is considered a weed e.g., in corn (Zea mays) or soybeans (Glycine max).