[Preventive chemical control of the neck rot fungus (Botrytis allii Munn) in onion (Allium, cepa L.)]
1993
Ramos N, Isabel del Pilar
The efficacy effects of the fungicides chlorothalonil, dicloran and chlorothalonil + metalaxyl on the neck rot fungus Botrytis allii M. in onion (Allium, cepa L.) were investigated under preharvest field, postharvest and in vitro conditions. Three experiments were conducted: 1) Chemical control of B. allii under in vitro conditions; 2) Fungus control during storage, prior mechanical inoculation; and 3) preharvest preventive control of neck rot with spray application of fungicides. In the in vitro experiment, the presence of any of the three fungicides interfered with the development of the fungus. Dicloran completely inhibited mycelial growth during the first nine days post-inoculation. No control was achieved with the other two treatments, which only partially retarded fungal growth, with no difference between them. In all treatments, a 50% increase in fungicide dosage resulted in less radial fungal development of B. allii. The postharvest experiment with chlorotalonil treatment resulted in the lowest percentage of infected bulbs, with the remainder of the treatments showing intermediate levels of control. The preharvest field experiment and postharvest evaluations showed no clear tendencies in preventive control with respect to fungicide use in the control of neck rot
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