Selectivity of clomazone and S-metolachlor applied after cassava pruning

Abstract

-The objective of this work was to evaluate the selectivity of clomazone in two formulations and S-metolachlor applied on shoots of different sizes after pruning of 'Baianinha' cassava. The experiment was arranged in a randomized block design in a factorial 5 x 2 (5 treatments x 2 sizes of shoots after pruning -10 and 33 cm) with four replications. The herbicides evaluated were: clomazone (encapsulated suspension -900 g h -1 ), clomazone (encapsulated suspension -1,080 g ha -1 ), clomazone (emulsifiable concentrate 900 g ha -1 ), S-metolachlor (1,920 g ha -1 ) and an untreated control. During the experiment, all plots were kept free of weed interference by hand weeding. It was concluded that both the formulations of clomazone and S-metolachlor were selective when applied on both the shoot sizes evaluated. However, the application of S-metolachlor on 33 cm shoots gave higher selectivity to 'Baianinha' cassava plants. Keywords:Manihot esculenta, microencapsulated, weed, clomazone, S-metolachlor. RESUMO -Objetivou-se neste estudo avaliar a seletividade do clomazone em duas formulações e do S-metolachlor aplicados em diferentes tamanhos de brotos depois da poda da mandioca Baianinha. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema fatorial 5 x 2 (5 tratamentos x 2 tamanhos de brotos após a poda -10 e 33 cm), com quatro repetições. Os herbicidas

Efficacy and Selectivity of Herbicides Applied in Cassava Pre-Emergence

“…Phytointoxication ( Every herbicide assessed in this study was selective for cassava, assuring the control of weeds without causing toxic effects to the crop even when applied in combinations. The results obtained in the present study corroborate those reported from earlier ones that demonstrated the selectivity of the herbicides clomazone, ametryn, metribuzin, flumioxazin, and isoxaflutole either when applied in isolation or in combinations (OLIVEIRA JR et al, 2001;BIFFE et al, 2010b;COSTA et al, 2013b).…”

Selectivity and efficiency of herbicides in cassava on the floodplain of the Solimões river

“…As cultivares de mandioca podem ser tolerantes aos herbicidas, não exibindo sintomas de intoxicação, sem alterações fisiológicas e redução de produtividade, ou pouco tolerantes, prejudicando o crescimento e a produtividade de raízes (OLIVEIRA JR. et al, 2001). Além do fator genético, as doses dos herbicidas e as condições ambientais têm influência na tolerância das cultivares aos herbicidas (COSTA et al, 2013).…”

“…Cassava cultivars may be tolerant to herbicides, showing no symptoms of toxicity, with no physiological changes or yield reduction, or little tolerant, impairing the growth and root yield (OLIVEIRA JR. et al, 2001). In addition to the genetic factor, the herbicide doses and the environmental conditions can influence the tolerance of the cultivar to herbicides (COSTA et al, 2013).…”

Sequential Application of Herbicides Alone and in Mixture With and Without Foliar Fertilizer after Pruning of Cassava Plants

“…Cassava has a productive potential of 24 to 32 t ha -1 in cycles of 10 to 12 months and of 35 to 73 t ha -1 in cycles of 18 months (Fey et al, 2007;Otsubo et al, 2008;Devide et al, 2009;Costa et al, 2013). However, crop yield may be reduced due to competition with weeds, mainly because it has slow initial growth (Azevedo et al, 2000).…”

“…The crop undergoes a period of physiological rest in the interval between the first and second crop cycle, characterized by the stoppage of vegetative growth and plant defoliation, which occur in the coldest or driest season of the year when pruning is carried out by farmers . After pruning, a new flow of growth of the crop and weed seed bank occur, making it necessary to elaborate control strategies with selective and efficient herbicides (Costa et al, 2013).…”