Resistance to dicarboximide and benzimidazole fungicides in Botrytis cinerea from greenhouse tomatoes in New Zealand

Isolates from Botrytis cinerea collected from greenhouse tomato crops throughout New Zealand were tested for resistance to the dicarboximide fungicide vinclozolin and the benzimidazole fungicide carbendazim by assessing fungal growth on agar media amended with the fungicides (100 ppm active ingredient for both fungicides) Benzimidazole resistant strains of B cinerea were found on 15 of the 18 properties examined and dicarboximideresistant strains were found on 11 properties Dicarboximide resistance was more prevalent in the Auckland region with 71 of isolates resistant compared to 5 of isolates resistant for the other three regions All of the strains that were resistant to dicarboximide were also resistant to benzimidazole The high levels of dicarboximide resistant strains in the Auckland region correspond to reported loss of fungicide efficacy and loss of disease control in some greenhouses in this region