Beschreibung:
Pyrithiobac-sodium is a selective systemic herbicide for cotton, widely used for weed control in thiscrop. This herbicide has soil activity, but little is known about the effect of the residual in the weedscontrol. This study aimed to evaluate the effect of residual activity of pyrithiobac-sodium in thecontrol of important weeds of cotton crop. Five experiments were conducted (number of weeds) ingreen-house. The experiment was installed in a factorial arrangement (3 x 4) + 1, it was three timesof application of the herbicide before sowing (20, 10 and 0 DBS) and four doses of pyrithiobacsodium(28, 56, 84 and 112 g ha -1), and an additional treatment that served as a control withoutherbicide. Residual activity of pyrithiobac-sodium caused restriction of the vegetative growth of allweeds. The species that demonstrated high sensibility to the residual activity of pyrithiobac-sodiumwere, in descending order: apple of Peru (Nicandra physaloides), american black nightshade(Solanum americanum), buttonweed (Spermacoce latifolia), benghal dayflower (C. benghalensis)and morning glory (I. grandifolia).
O pyrithiobac-sodium é um herbicida sistêmico seletivo para o algodoeiro, sendo amplamente utilizado para o controle de plantas daninhas nesta cultura. Este herbicida apresenta atividade no solo, porém pouco se conhece sobre os efeitos deste residual no controle de plantas daninhas. Este trabalho teve como objetivo avaliar o efeito da atividade residual do pyrithiobac-sodium no controle das principais plantas daninhas da cultura do algodoeiro. Foram conduzidos cinco experimentos (número de espécies avaliadas) em casa-de-vegetação. Cada experimento foi instalado em arranjo fatorial (3 x 4) + 1, sendo três épocas de aplicação do herbicida antes da semeadura (20, 10 e 0 DAS) e quatro doses de pyrithiobac-sodium (28, 56, 84 e 112 g ha-1), além de um tratamento adicional que serviu de testemunha sem herbicida. A atividade residual do pyrithiobac-sodium causou restrição no desenvolvimento vegetativo e todas as plantas daninhas. As espécies com maior sensibilidade a atividade residual do pyrithiobac-sodium, em ordem decrescente, foram: N. physaloides, S. americanum, S. latifolia, C. benghalensis e I. grandifolia. Sensibility of weeds to the residual activity of pyrithiobac-sodiumAbstractPyrithiobac-sodium is a selective systemic herbicide for cotton, widely used for weed control in thiscrop. This herbicide has soil activity, but little is known about the effect of the residual in the weedscontrol. This study aimed to evaluate the effect of residual activity of pyrithiobac-sodium in thecontrol of important weeds of cotton crop. Five experiments were conducted (number of weeds) ingreen-house. The experiment was installed in a factorial arrangement (3 x 4) + 1, it was three timesof application of the herbicide before sowing (20, 10 and 0 DBS) and four doses of pyrithiobacsodium(28, 56, 84 and 112 g ha -1), and an additional treatment that served as a control withoutherbicide. Residual activity of pyrithiobac-sodium caused restriction of the vegetative growth of allweeds. The species that demonstrated high sensibility to the residual activity of pyrithiobac-sodiumwere, in descending order: apple of Peru (Nicandra physaloides), american black nightshade(Solanum americanum), buttonweed (Spermacoce latifolia), benghal dayflower (C. benghalensis)and morning glory (I. grandifolia).