PRE-AND POST-EMERGENCE HERBICIDE SELECTIVITY IN PEANUTS AT AN EARLY STAGE

Abstract

Studies on herbicide selectivity to peanuts detected differences according to the evaluated active ingredient and genotypes. This study analyzed the herbicide selectivity of two genotypes at an early stage. Pre-emergence (trifluralin, pendimethalin, diclosulam, s-metolachlor, imazethapyr + flumioxazin, clomazone, sulfentrazone, and imazapic) and post-emergence (imazapic, bentazon, bentazon + imazamox, clethodim, quizalofop-p-ethyl, cloransulam-methyl, s-metolachlor, lactofen, 2,4-D, and carfentrazone) applications were assessed in 1253 OL and 2133 OL breeding lines. The effects of pre-(PRE) and postemergence (POST) herbicides were the same for both genotypes, with PRE not affecting seedling emergence and shoot and root dry mass. Diclosulam was among the most selective PRE herbicides, while the clomazone treatment caused only mild damage. All tested POST herbicides caused damage for up to 14 days after application (DAA). At 28 DAA, most herbicides exhibited the same damage as the untreated control. Lactofen caused mild damage (11.8%) without reducing plant height and shoot and root dry mass. Diclosulam, clomazone, and lactofen are unregistered for peanut crops in Brazil, and further studies should test their selectivity for peanut cultivars. Screening studies on selectivity to imazapic, 2,4-D, and carfentrazone are also relevant to identifying sources of tolerance in peanut germplasm.