Efficacy and Selectivity of Herbicides Applied in Cassava Pre-Emergence

Abstract

The interference imposed by weeds can cause damages to cassava development. Thus, adopting control measures is fundamental. The use of pre-emergence herbicides is one of the control alternatives, since cassava presents a good tolerance to herbicides applied in this modality. However, herbicides may present differential selectivity due to the variety of cassava that is planted. The objective of this study was to evaluate both weed control effectiveness and selectivity of different herbicide combinations applied at pre-emergence of two cassava varieties. Two experiments were established in the field using a randomized complete block design, in a split plot scheme, with four replications. In the efficacy experiment, application of six combinations of herbicides, including clomazone + ametryn, clomazone + metribuzin, clomazone + flumioxazin, isoxaflutole + ametryn, isoxaflutole + metribuzin, isoxaflutole + flumioxazin were evaluated in the main plot. In addition, a non-treated control and a weeded control were evaluated. In the subplots, the Caravela and Pretinha varieties were planted. For the selectivity experiment, a non-treated control was not included. The combinations containing clomazone presented a longer residual period of weed control as well as a better control of benghal dayflower. Metribuzin exhibited lower efficacy than other herbicide combinations containing clomazone or isoxaflutole. The Pretinha variety showed greater tolerance to weed interference. Every herbicide combination that was applied in cassava pre-emergence presented selectivity for both Caravela and Pretinha varieties.

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“…A persistência do clomazone em condições aeróbicas pode variar de 47 dias em solo franco-argiloso (Tomco et al, 2010) a 117 dias em solo muito argiloso (Marulanda, 2017). Santiago et al (2018) relataram que misturas de herbicidas contendo o clomazone (1080g de i.a ha -1 ) tiveram persistência de 91 dias no controle de plantas daninhas (Amaranthus deflexus, Commelina benghalensis, Conyza sp., Heliotropium indicum, Mollugo vercillata, Cenchrus echinatus, Digitaria insularis e Eleusine indica) nas cultivares de mandioca Caravela e Pretinha cultivadas em um Latossolo Amarelo de textura franco-arenosa. A persistência do diuron pode variar de 49 dias em solos arenosos (Stork, Bennet & Bell, 2008) a 91 dias em solos argilosos (Rocha et al, 2013).…”

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

“…A estratégia de controle de plantas daninhas mais empregada nos sistemas de produção de mandioca no Amazonas é a capina, com uso de facões, enxadas e foices. O controle químico tem como vantagens principais a eficácia de controle elevada, maior rendimento operacional e menor custo, resultando em maiores eficiência agronômica e econômica (SILVA et al, 2012;SANTIAGO et al, 2018).…”

“…Por ser a mandioca uma cultura de crescimento inicial lento e pouco eficiente no sombreamento da superfície do solo, a aplicação de herbicidas em préemergência (PRE) da cultura e das plantas daninhas promove o controle eficaz das plantas daninhas nesta fase de maior suscetibilidade à interferência negativa (SCARIOT et al, 2013;SANTIAGO et al, 2018).…”

Postharvest conservation of minimally processed cassava roots subjected to different packaging systems

“…This crop is fundamental for the Brazilian socioeconomic scenario, with cultivation in both small and large farms. Moreover, cassava is versatile, with potential to be planted in all regions of Brazil (Santiago et al, 2018).…”