Evaluation of systemic and protectant fungicides for the control of Sigatoka leaf spot (Mycosphaerella musicola Leach) of bananas in North Queensland

Abstract

Ten fungicides were evaluated in 3 experiments over 3 years for control of Sigatoka leaf spot, which is the major foliar disease of bananas in North Queensland. Benomyl(150 g a.i./ha), bitertanol(126 g a.i./ha), carbendazim (1 50 g a.i./ha), DPX H6573 (100 g a.i./ha), mancozeb (1760 g a.i./ha), nuarimol (60 g a.i./ha), propiconazole (50 g a.i./ha), RH3866 (250 g a d h a ) and triademenol (100 g a.i./ha), all applied with mineral oil (4 L/ha), and chlorothalonil (1300 g and 900 g a.i./ha) and propiconazole (100 g a.i./ ha), applied alone, all reduced the severity of leaf spot (P < 0.05). Bunch weights were increased by all fungicides compared with untreated plants during 1984 (P < 0.05). Effective disease control reduced the problem of premature fruit ripening from 100% of bunches in untreated plots to 0% in propiconazole (50 g a.i./ ha + oil and 100 g a.i./ha alone) treatments. Propiconazole was the most effective fungicide, applied either continuously (50 g a.i./ha + oil, or 100 g a.i./ha alone) or alternated (50 g a.i./ha + oil) with mancozeb + oil in a spray program. Propiconazole, bitertanol and nuarimol significantly reduced the size of Sigatoka lesions (P=0.05). An experimental fungicide DPXH6573 gave good disease control in 1985 and warrants further investigation.