The somatic recombinogenic activity of the phenylpyrrole fungicide fludioxonil, in diploid Aspergillusnidulans was found similar to that caused by aromatic hydrocarbon and dicarboximide fungicides (AHDFs), such as iprodione, chlozolinate and tolclofos–methyl. All these fungicides not only increased the number of mitotic recombinants but also provided similar appearance, small sectors, of white and yellow mitotic recombination products. Fludioxonil highly resistant strains (resistant factor approximately 5000) of Botrytis cinerea were isolated at high frequency (1.08 × 10−5). Study of cross‐resistance patterns of mutant strains to other fungicides, revealed cross‐resistance of fludioxonil with dicarboximides (iprodione, procymidone, and chlozolinate) and aromatic hydrocarbons, such as tolclofos–methyl, pentachloronitrobenzene (PCNB), tecnazene and chloroneb. The positive cross‐resistance relationships found between phenylpyrroles and members of the AHDFs and their ability to increase mitotic instability in diploid A.nidulans, indicate that phenylpyrroles should be included with AHDFs. A study of fitness parameters in wild‐type and representative fludioxonil‐resistant mutants of B. cinerea, showed that the mutation(s) leading to fludioxonil resistance may or may not affect some fitness‐determining characteristics, such as sensitivity to high osmolarity, growth rate, conidial germination and germ‐tube elongation. Pathogenicity tests on cucumber seedlings showed that an osmosensitive representative strain of B. cinerea, resistant to fludioxonil, was as virulent as the wild‐type strain. The phenylpyrrole fungicide was ineffective, even in high concentrations, to control grey mould caused by this isolate.
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.
Plant Protection Products (ppp s ) have been evaluated and authorised in the European Union (EU), in accordance with a harmonised regulatory system (Dir. 91/414/EEC), since 1993. Efficacy evaluation is an integral part of the EU regulatory system of registration of ppp s (Dir. 91/414/EEC) and is the main subject of this review paper. The efficacy data requirements and evaluation principles are analyzed and discussed along with an outline presentation of the evaluation systems of the EU. The trials needed for the efficacy evaluation of plant protection products (ppp s ) across EU have to be conducted according to the principles of Good Experimental Practice by officially recognized testing facilities and in line with the methods specified by the Standards of the European and Mediterranean Plant Protection Organization. For registration purposes, the efficacy parameters which should be considered in the experimentation and evaluation of a ppp, according to EU criteria, are effectiveness (direct efficacy), resistance risk and the absence of undesirable effects on: a) plants or plant products (phytotoxicity, yield, quality), b) succeeding and adjacent crops, c) plants or plant products used for propagation, and d) beneficial arthropods. Efficacy and other desirable effects from the use of ppp s have to be weighed against their potential phytotoxicity and/or other undesirable effects during the evaluation process. The evaluation of efficacy data of ppp s , provided by the notifiers in the Biological Assessment Dossier, and the decision taken on authorization are performed across Member States on the basis of the "Uniform Principles" of the EU. Experience gained in implementing the provisions of Dir. 91/414/EEC has demonstrated that a number of changes are required. The main changes to this system, which are in progress, and also other systems on efficacy evaluation of ppp s outside EU are discussed.
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