Low-level benzimidazole resistance in Botrytis cinerea in New Zealand

Abstract

The resistance of selected New Zealand strains of Botrytis cinerea Pers.: Fr. to the benzimidazole fungicide carbendazim was studied by measuring radial growth rate on fungicide-amended agar media. Three classes were recognised: sensitive, with median effective concentration (EC₅₀) values for mycelial growth rate of 0.03-0.05 mg/litre; low-level resistant, with EC₅₀ values of 4- 6 mg/litre;- and high-level resistant, with EC₅₀ values of = 100 mg/litre. Low-level resistant isolates are rare, being recovered only from one glasshouse in Christchurch, whereas high-level resistant isolates are common throughout New Zealand.

Keywords:

• Botrytis cinerea
• benzimidazole fungicides
• carbendazim
• fungicide resistance