Distribution of Thiabendazole-Resistant Colletotrichum musae Isolates from Guadeloupe Banana Plantations

In Guadeloupe, anthracnose of bananas, caused by Colletotrichum musae, is commonly controlled by postharvest thiabendazole treatments. A survey was conducted in 45 banana packing stations of Guadeloupe to determine the proportion of isolates that were resistant to thiabendazole. Isolates resistant to thiabendazole concentrations of 1 μg/ml (R1), 5 μg/ml (R5), and 50 μg/ml (R50) were detected. Most of the resistant isolates were R1 or R5, and of 1,350 isolates, the proportion of resistant isolates (R1 + R5 + R50) was 23%, ranging from 0 to 70% depending on the location. The presence of resistant isolates was correlated with the exclusive use of benomyl as foliar aerial sprays from 1972 to 1982 to control Sigatoka disease. Isolates resistant to concentrations of 1 and 5 μg/ml were as pathogenic as the susceptible isolates and were not controlled satisfactorily by postharvest thiabendazole treatments. Alternative control measures and the importance of resistance in terms of anthracnose control in Guadeloupe are discussed.