INFLUENCE OF BROADLEAF WEEDS ON CHLOROTHALONIL DEPOSITION, FOLIAR DISEASE INCIDENCE, AND PEANUT (ARACHIS-HYPOGAEA) YIELD

Field experiments were conducted at Jay and Marianna, FL in 1988 and 1 989 to determine the effects of sicklepod, Florida beggarweed, and com mon cocklebur density on chlorothalonil deposition to peanut foliage, peanut foliar disease incidence, and peanut yield, At a density of fou r weed plants per 8 m of row, Florida beggarweed and sicklepod reduced chlorothalonil deposition on peanut foliage by 20%, while common cock lebur reduced fungicide deposition by 34%. At the same density, incide nce of the foliar diseases early leaf spot and late leaf spot increase d 10% with Florida beggarweed, 14% with sicklepod, and 20% with common cocklebur compared with weed-free peanut, The predicted peanut yield loss from a weed density of four plants per 8 m was 16 to 19% for Flor ida beggarweed, 23 to 25% for sicklepod, and 31 to 39% for common cock lebur. Weed biomass increased with increasing weed density.