This research was conducted to determine the effect of sowing time on weed interference periods in peanut crop (Arachis hypogaea cv. IAC Runner 886). Two experiments were set at different times, early November and December 2005, at neighboring areas originated from sugar-cane renewal in Jaboticabal, SP. The experiment was arranged in a randomized block design,with the treatments consisting of increasing periods of weed coexistence or weed control in the peanut crop. The main weed species in the area were: Ipomoea triloba, Digitaria nuda, Hyptis lophanta and Sida spp. The weed community and the peanut crop were influenced by sowing time, modifying their interference relations. Weed shoot dry biomass for the second period exceeded in 23.7% those found at the first period throughout the crop development cycle, specially reflecting decreased peanut bean productivity. Assuming a tolerance of 5% for peanut bean production decrease, it was verified that the period before interference (PBI) for the first time was 28 days after emergence, and the entire period of interference prevention (EPIP) was of 79 days after emergence, with a productivity reduction of 53.5%. At the second time, weed interferences in the peanut crop were the worst, with production being affected more intensely and reduced to 86%, with a PBI of 33 and a EPIP of 93 days after emergence. When the peanut crop sowed earlier (November) was kept weed-free, throughout the crop cycle, green bean productivity was higher, 23.7% more than the peanut crop sowed a month later.
Arachis hypogaea; competition; control
