INTEGRATED MANAGEMENT OF SCLEROTINIA BLIGHT IN PEANUT - UTILIZING CANOPY MORPHOLOGY, MECHANICAL PRUNING, AND FUNGICIDE TIMING

Sclerotinia blight of peanut, caused by Sclerotinia minor, generally b ecomes severe only after vines meet in the row middles and a dense can opy develops. Dense foliage appears to support a microclimate conduciv e to the colonization of peanut limbs by S. minor. Removal of excess f oliage before and during a Sclerotinia blight epidemic on the suscepti ble genotype NC 7 has been shown to reduce the rate of disease progres s. Field tests in 1993 and 1994 examined control of Sclerotinia blight among four peanut genotypes (NC 7, VA 93B, NC Ac 18016, and Tamspan 9 0) with diverse canopy morphologies. Each cultivar had foliage pruned with a rotary mower once (1993 and 1994) or twice (1994) during the se ason. Applications of fluazinam (9.2 kg a.i./ha) were imposed on the g enotype x pruning treatments. Soil temperatures under the canopy of ea ch genotype and pruning treatment were measured and compared. Disease data were collected weekly by counting the number of feet of plants ex hibiting lesions with visible fungus growth. Tamspan 90, a resistant S panish peanut, had the least Sclerotinia blight incidence. Pruning mea surably affected soil temperature for approximately 2 weeks following pruning. Removal of foliage reduced disease and increased disease cont rol affected by fluazinam in fields with high disease pressure. In som e tests, yields were increased by pruning through a reduction in disea se pressure. Yields were lower when peanuts were pruned excessively, e specially late in the season. Pruning of excessive vine growth can be an alternative, or complement, to fungicide treatments when done in mi dseason during favorable weather when moderate to high disease pressur e occurs.