Activity of Fluazinam against Strains of Botrytis cinerea Resistant to Benzimidazoles and/or Dicarboximides and to a Benzimidazole‐phenylcarbamate Mixture

Abstract

Fluazinam is a new active ingredient for the control of grey mould, belonging to the novel broad spectum phenylpyridinamine fungicides. The effect of fluazinam was studied on one wild type and four strains of Botrytis cinerea, which had been isolated from vegetable crops in Greece, and were resistant to benzimidazoles and/or dicarboximides and to the mixture of benzimidazoles (carbendazim) + phenylcarbamates (diethofencarb). In vitro fluazinam was found to be highly active against strains of B. cinerea which were sensitive or resistant to benzimidazoles or exhibited multiple resistance to benzimidazoles, dicarboximides and to the mixture carbendazim + diethofencarb [EC50 and EC95 values (concentration of active ingredient that suppresses mycelial growth to 50 and 95%, respectively, of that of the fungus on fungicide‐free agar medium) calculated with probit analysis, ranged from 0.044 to 0.069 and 0.58 to 1.6 μg/ml, respectively]. No cross‐resistance was observed between fluazinam and the market products benomyl, iprodione or carbendazim + diethofencarb. Preventive applications of fluazinam in vivo completely inhibited infections of cucumber seedlings by all the above‐mentioned resistant strains of B. cinerea. Benomyl and iprodione did not effectively control the benzimidazole‐ and dicarboximide‐resistant strains. The mixture of carbendazim + diethofencarb insufficiently controlled the strain of B. cinerea with moderate resistance to benzimidazoles. The results of this investigation indicate that it should be possible to use fluazinam as an alternative in resistance management programmes against grey mould.

Screening of Botrytis cinerea isolates from vineyards in Israel for resistance to fungicides

“…Fluazinam inhibits the germination of Botrytis conidia, as well as its germ tube elongation and mycelial growth (Leroux 2004). EC 50 values for fluazinam-sensitive isolates, as defined using the mycelial growth test, have been shown to range from 0.04 to 0.07 μg ml −1 (Kalamarakis et al 2000) or from 0.005 to 0.020 μg ml −1 (Leroux et al 1999), depending on the technical specifications of the tests used and/or the population tested. In our work, the EC 50 values of 73 isolates had a bimodal distribution and ranged from 0.005 to 0.075 μg ml −1 , with a mean EC 50 value of 0.04 μg ml −1 .…”

Assessment of the Role of Local Strawberry Rhizosphere—Associated Streptomycetes on the Bacterially—Induced Growth and Botrytis cinerea Infection Resistance of the Fruit

“…Currently, the strains of B. cinerea resistant to two fungicide groups, benzimidazoles and dicarboximide are of particular concern as these chemicals are recommended and widely utilized for controlling disease on strawberries in Australia [4,5]. Biological control might be an alternative route to inhibit this pathogen by reducing the use of some chemical fungicides, which may in turn help to combat resistance problems often experienced with chemical control [6,7].…”

Nested PCR‐RFLP is a high‐speed method to detect fungicide‐resistant Botrytis cinerea at an early growth stage of grapes

“…Three fungicides, thiophanate‐methyl (benzimidazole), diethofencarb (phenylcarbamate) and procymidone (dicarboximide), have been used to control B. cinerea disease for many years. However, phenotypes exhibiting resistance to these fungicides have been detected in B. cinerea populations on host plants 4–6. A point mutation at codon 198 or 200 of β‐tubulin gene is thought to be associated with the resistance to benzimidazole and/or phenylcarbamate fungicides 7–12.…”