Field experiments evaluating three isolates of Trichoderma harzianum Rifai and a white spored Trichoderma sp. alone and in combination with fungicides and fungicide-insecticide/nematicide combinations were conducted during 1979-81 in an area with a history of high incidence of Sclerotium rolfsii Sacc. None of the Trichoderma sp. treatments alone, mixed with wheat middlings, or combined with carboxin reduced disease or increased yield over the control; however, disease was reduced when T. harzianum was applied with PCNB at 11.2 kg/ha. Trichoderma spp. appeared to be active only over a 3-8 day period, which was inadequate for control of S. rolfsii for the entire season. Treatments containing PCNB (11.2 kg ai/ha) alone or with the insecticide/ nematicides ethoprop (3.4 kg ai/ha), fensulfothion (3.4 kg ai/ha), and aldicarb (1.7 kg ai/ha) significantly increased yields 9 of 12 times with an average increase of 790 kg/ha; and significantly reduced disease loci at harvest 5 of 12 times with an average reduction of 36%. Ethoprop 10G alone at 3.4 kg ai/ha increased yield one of 3 times, but did not reduce disease. Aldicarb and phenamiphos alone did not decrease disease or increase yield. Carboxin 4G decreased disease and increased yield only when applied at 1.12 kg ai/ha six times on an as required basis. Carboxin 3F at 0.84 kg ai/ha applied 6 times and carboxin 75W at 1.27 kg ai/ha applied one time did not increase yield or reduce disease at harvest.

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Author notes

1Cooperative Investigations of SE, ARS, U. S. Department of Agriculture, and the University of Georgia College of Agriculture Experiment Station, Tifton, Georgia 31793.

Mention of a pesticide herein neither constitutes a recommendation nor implies registration under FIFRA.