Control of vascular-streak dieback of cocoa with triazole fungicides and the problem of phytotoxicity
The effectiveness of a range of systemic fungicides against vascular-streak dieback of cocoa, caused by Oncobasidium theobromae, was evaluated over 2 years in Papua New Guinea. Monthly foliar sprays of the triazole fungicides hexaconazole, tebuconazole and triadimenol all gave good protection against the disease. The relative efficacy of these chemicals was, in order, tebuconazole (EC50 0.90 mg a.i. per plant), hexaconazole (EC50 2.35 mg a.i. per plant), triadimenol (EC50 4.17 mg a.i. per plant). However, the relative severity of plant growth inhibition induced by these componds had the same ranking. Growth inhibition was reduced by extending the interval between treatments, but this also reduced the efficacay of disease control. Propiconazole stem paints (EC50 25.02 mg a.i. per plant) were markedly less effective than these sprays. Neutralized phosphorous acid sprays and paints showed no activity against the disease.
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| Format: | biblioteca |
| Published: |
Jun
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| Subjects: | THEOBROMA CACAO, ONCOBASIDIUM THEOBROMAE, MUERTE DESCENDENTE, ENFERMEDADES FUNGOSAS, FUNGICIDAS, ACCION SISTEMICA, FITOTOXICIDAD, PAPUA NUEVA GUINEA, |
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