Comparative efficacy of triazoles and conventional fungicides in the control of vascular streak dieback (VSD) in cocoa
1987
Ng Kwang Yew (Bayer Sdn. Bhd., Kuala Lumpur (Malaysia))
Among the following fungicides evaluated on cocoa nursery seedlings in Sabah: triforine, carbendazim, oxycarboxin, propiconazole, triadimenol (R Bayfidan) and benomyl, Bayfidan 250 EC at 5 mg ai/seedling soil drenched at 30-day intervals was most effective in preventing VSD [vascular streak dieback] infection. No phytotoxicity was observed at this rate but slight foliar phytotoxicity was observed at 10 mg ai/seedling. The other chemicals provided a relatively lower degree of control when used at rates from 5-30 mg ai/seedling. In a separate trial on cocoa nursery seedlings, Bayfidan 250 EC foliar sprayed at 0.00625% ai at 7-day intervals and 0.0125% ai at 14-day intervals provided efficacies at 96% without any phytotoxic effects. On newly field-planted cocoa, similar results were obtained by foliar spraying at 0.0125 ai at 7-day intervals and 0.025% ai at 14-day intervals as well as soil drenching at 50 and 100 mg ai/plant at 30-day intervals. Possible factors for the enhanced efficacy of Bayfidan, a triazole compound, against VSD by soil drenching in comparison to foliar spraying are discussed.
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