USE OF ELISA AND ISOLATION FOR DETERMINING THE DISTRIBUTION OF RHIZOCTONIA-SOLANI AND OTHER RHIZOCTONIA SPP IN ASYMPTOMATIC CREEPING BENTGRASS

A commercial Rhizoctonia-specific ELISA was compared with isolation on antibiotic-amended water agar for the detection of Rhizoctonia solani and other Rhizoctonia spp. in asymptomatic creeping bentgrass near ac tive brown patch disease centres. A greater number of positive samples were indicated by ELISA than by isolation in tests of foliage and roo t tissues. Over 75% agreement was found between ELISA and isolation wi th foliage, but the presence of Rhizoctonia spp. in root tissues could not be confirmed by isolation from any of the ELISA-positive samples. There was poor agreement between the two methods in assays of organic matter from thatch. Greater numbers of thatch samples were positive f or Rhizoctonia spp. by isolation than by ELISA. Pathogenic R. solani w as found by both methods in asymptomatic foliage as far as 30 cm from the margins of brown patch disease areas. There was a more restricted distribution of the fungus in the thatch. Detection of the fungus in r oot tissues from asymptomatic areas by ELISA could not be confirmed by isolation.