Resumo

ESQUEDA-ESQUIVEL, Valentín A.  e  TOSQUY-VALLE, Oscar Hugo. Chemical control of propanil-resistant Echinochloa colona (L.) Link and Cyperus iria L. in rainfed rice (Oryza sativa L.) in Tres Valles, Veracruz. Universidad y ciencia [online]. 2013, vol.29, n.2, pp.113-121. ISSN 0186-2979.

A study was carried out in 2009 in Tres Valles, Ver. in order to determine the effectiveness of new herbicides in the control of propanil-resistant E. colona (L.) Link and C. iría L. in a rainfed rice (Oryza sativa L.) crop. Seven treatments were evaluated in an experimental design with random complete blocks and four replicates. The tratments were: 1. Cyhalofop-butyl (360 g ha⁻¹), 2. Bispyribac-sodium (30 g ha⁻¹), 3. Cyhalofop-butyl + clomazone (315 + 480 g ha⁻¹), 4. Bispyribac-sodium + clomazone (315 + 480 g ha⁻¹), 4. Bispyribac-sodium + clomazone (22 + 480 g ha⁻¹), 5. Propanil + clomazone (2 160 + 480 g ha⁻¹), 6. Propanil / propanil (3 600 / 3 600 g ha⁻¹) and 7. a control withgrowth of weeds and the toxicity to the rice were evaluated at days 15, 30 and 45 after treatment (DAT) and the final height and grain yield of the rice were recorded. At DAT 45 the highest E. colona controls were obtained with cyhalofop-butyl alone, cyhalofop-butyl + clomazone and bispyribac-sodium. These treatments and the mixture of bispyribac-sodium + clomazone produced grain yields of 4.83 to 5.54 t ha⁻¹, grater than those of the other treatments. The addition of bispyribac-sodium alone and combined with clomazone and cyhalofop-butyl mixed with clomazone proved to be less than 4 % toxic to the rice crop. It was established that both cyhalofop-butyl and bispyribac-sodium, alone and combined with clomazone, are better alternatives for controlling E. colona than the sequential addition of propanil and the mixture of propanil + clomazone, whereas in order to control C. iria with the new herbicides, only bispyribac-sodium alone or combined with clomazone may be used.

Palavras-chave : Herbicides; toxicity; grain yield.

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