Selectivity of herbicides applied in post-emergence on physic nut (Jatropha curcas L.)

Abstract

The lack of information on herbicides selective for cultivation of physic nut makes it difficult to tame the chemical control of weeds, especially during the initial stage of the crop. Therefore, the objective of this study was to evaluate the selectivity of herbicides applied in post-emergence to the culture of physic nut (Jatropha curcas L.). We used experimental design completely randomized with 16 treatments and 11 repetitions, three herbicides in five doses and a control without herbicide. The doses of herbicides (L ha^-1) were: glyphosate (180, 450, 720, 990 and 1.260 g ha^-1), fluazifop-p-butyl (100, 125, 150, 175 e 200 g ha^-1) and 2,4-D amine (720, 1.080, 1.440, 1.800 e 2.160 g ha^-1). The herbicides were applied 55 days after sowing, when the plant seedlings had two to three pairs of leaves. Of the three herbicides applied in post-emergency, only fluazifop-p-butyl and glyphosate at the lower dose, was completely selective to plant seedlings physic nut and is promising for the control of weeds in young plantations. None of the herbicides affected the height of the plant seedlings, though the herbicide glyphosate (in higher doses) and 2,4-D amine showed toxic effects with changes in appearance and morphology of plant seedlings.