Effectiveness of herbicides in weed control and selectivity in culture Runner IAC 886 peanut.
It was aimed to verify the efficacy and selectivity of herbicides applied alone or in tank mixture for the weed control in peanut crop cv Runner IAC 886. Therefore, it was settled a field experiment, in a randomized block design with four replications. The treatments applied in pre-emergence were: 1-imazapic, 3-imazapic+pendimethalin, and 5-imazapic+trifluralin; the treatments applied in post-emergence were: 2-imazapic, 4-imazapic+pendimethalin, and 10-imazapic + (bentazon+paraquat); and treatments with application in PRE followed by POST were: 6-trifluralin and imazapic, 7-trifluralin and bentazon, 8-trifluralin and 2,4-D, 9-imazapic and bentazon+paraquat; besides the checks with and without weeding (treatments 11 and 12, respectively). It were evaluated the efficacy of herbicides and symptoms of intoxication in peanut plants by visual evaluations at 7, 14, 21, 28, 45, and 90 days after application, and, after the harvest, the pods yields. Treatments 2, 3, 4, 5, 6, 7, and 8 had no significant reduction in peanut productivity. Treatment 10 was the least effective in controlling weeds and presented yields 47.3% lower than treatment 3 and 51.2% lower than the weeded control. It was concluded that for a weed community composed mainly of Cenchrus echinatus, Acanthospermum hispidum, Amaranthus deflexus, Parthenium hysterophorus, Alternanthera tenella, and Eleusine indica, the best weed control was obtained by imazapic in post-emergence. The application of imazapic + (bentazon+paraquat) in post-emergence was not effective in controlling weeds, resulting in yield losses.