COMPOST MANAGEMENT OF BROWN PATCH DISEASE IN TURFGRASS

Five Greek composts were evaluated for their suppressiveness against Rhizoctonia solani Kühn, an important soil borne pathogen causing Brown Patch disease of turfgrass. Two strains of R. solani belonging to anastomosis groups AG5 and AG2-2 IIIB were used to inoculate two turfgrass species (Lolium perenne L. ‘Applaud’ and Festuca arundinacea Schreb. ‘Tomahawk’). For AG5, percent disease ranged from 71.25 to 97.50 for Lolium and 27.50 to 92.50 for Festuca. For AG2-2 IIIB disease ranged from 45 to 100 % and 7.50 to 100 % for the above turfgrass cultivars, respectively. AG5 isolate was more aggressive than AG2-2 IIIB for both species tested. L. perenne was more susceptible to both isolates than F. arundinacea. Most of the composts were effective against both AGs. However, compost effectiveness was found to depend on the host/isolate combination. It was less pronounced in the more aggressive isolate (AG5) and the more susceptible host (L. perenne). Among the compost samples tested, composted horse manure (GR6) and composted olive mill waste with grape mark (GR8) were significantly better than the untreated control, while spent mushroom substrate (GR3) was overall the less effective compost, since disease incidence in some treatments was even higher than non-treated turfgrass pots.