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Improved Biocontrol Efficacy of Trichoderma harzianum 1295-22 for Foliar Phases of Turf Diseases by Use of Spray Applications

Trichoderma harzianum strain 1295-22 is an effective biocontrol agent for several fungal diseases. The efficacy of granule and spray applications of strain 1295-22 for control of Pythium root rot, brown patch, and dollar spot of creeping bentgrass was investigated. Spray applications of conidial suspensions (SA) of strain 1295-22 significantly reduced all three diseases of creeping bentgrass turf in both greenhouse and field experiments. Control was greatest when Triton X-100 at 0.1% was added to aqueous spray suspensions. When SA were applied weekly, the biocontrol treatments were equivalent to standard fungicides. Broadcast granule applications (GA) also significantly reduced foliar symptoms of Pythium root rot, dollar spot, and brown patch; turf quality also was enhanced. The populations of Trichoderma spp. in the root zone of a bentgrass putting green treated with SA or GA of strain 1295-22 increased 10- to 100-fold after treatment compared with untreated plots. However, strain 1295-22 was present at high levels on bentgrass leaves only following SA. Collectively, the results suggest that strain 1295-22 possesses both rhizosphere and phylloplane competence. The combination of broadcast applications of granules followed by spray applications of conidia reduced damage from both root and foliar diseases.