Effect of a select group of seed protectant fungicides on growth of Sclerotinia minor in vitro and its recovery from infested peanut seed.

ABSTRACT Potato-dextrose agar containing 100 μg of streptomycin sulfate per milliliter of medium (SPDA) was amended to establish levels of 0, 2, 4, 6, 8, and 10 μg/ml of the fungicides thiophanate-methyl, carboxin, dicloran, captan, pentachloronitrobenzene (PCNB), or thiram. Fresh mycelial plugs, dry mycelial fragments, and sclerotia of Sclerotinia minor were placed onto the amended media, and mycelial growth and sclerotial germination were determined for 7 days. Thiophanate-methyl was the most effective chemical in inhibiting growth of S. minor, followed by PCNB and dicloran. Thiophanate-methyl was the only chemical that prevented germination of sclerotia of S. minor. Peanut seed naturally infested with S. minor was treated with the fungicides alone or in various combinations; control seed was treated with talcum powder. Seed was stored in polyethylene bags for 12 weeks at 24°C. To determine the incidence of viable S. minor in treated seed, seed was removed from bags, washed for 1 min in 0.2% unscented, ...