Occurrence of strobilurin-resistant strains of Colletotrichum gloeosporioides (Glomerella cingulata), the causal fungus of strawberry anthracnose.

Isolates of Colletotrichum gloeosporioides (Glomerella cingulata), obtained from strawberry leaves with anthracnose in Saga Prefecture in 2003, were bioassayed for sensitivity to strobilurin fungicides (azoxystrobin and kresoxim-methyl). The two isolates had little sensitivity to these fungicides, and they were regarded as resistant. Sequence analysis showed that the deduced amino acid at codon 143 of the mitochondrial cytochrome b gene was altered from glycine (GGT) to alanine (GCT). Polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) using the restriction enzyme ItaI could be employed in practice for rapid testing of resistance to strobilurin fungicides.