Control of Cylindrocladium Black Rot of Peanut with Soil Fumigants Having Methyl Isothiocyanate as the Active Ingredient. P. M. Phipps, Professor of Plant Pathology, Tidewater Agricultural Experiment Station, Virginia Polytechnic Institute and State University, Suffolk, VA 23437. . Plant Dis. 74:438-441. Accepted for publication 12 November 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0438.

Metham-sodium and 1,3-dichloropropene (1,3-D) plus methyl isothiocyanate (MIT) were evaluated for control of Cylindrocladium black rot (CBR) of peanut (Arachis hypogaea) in naturally infested fields. In three tests (1981–1983), metham-sodium at 36 and 72 kg/ha suppressed disease incidence in peanut cv. Florigiant (CBR-susceptible) by 39 and 85% and increased yields by 536 and 545 kg/ha, respectively. In four subsequent tests (1984–1987), metham-sodium at 36 and 72 kg/ha and 1,3-D at 15.4 kg/ha plus MIT at 7.7 kg/ha reduced disease incidence in Florigiant by 77, 84, and 51% and in NC 8C (CBR-resistant) by 62, 89, and 48%, respectively. The above treatments increased yields of Florigiant by 1,012, 1,032, and 810 kg/ha and of NC 8C by 620, 627, and 550 kg/ha, respectively. Without soil fumigation, NC 8C had 54% less disease and 532 kg/ha more yield than Florigiant. Soil fumigation and planting NC 8C significantly suppressed the buildup of microsclerotial populations of Cylindrocladium crotalariae in soil during the growing season compared with planting NC 8C alone or planting Florigiant with or without soil fumigation. Preplant soil treatment with either metham-sodium at 36 kg/ha or 1,3-D at 15.4 kg/ha plus MIT at 7.7 kg/ha followed by planting a CBR-resistant cultivar is recommended for control of CBR in peanut.

Keyword(s): Calonectria crotalariae, chemical control, cultivar resistance, groundnut.