Pesticide Resistance Strategies and Tactics for Management (1986) / Chapter Skim
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Detection and Monitoring of Resistant Forms: An Overview
Detection and Monitoring of Resistant Forms: An Overview
Pages 298-312
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From page 298... ...
"Detection" indicates simply the obtaining of initial evidence for the presence of resistant forms in one or more field populations of the target organism. Consideration of the degree of resistance, the proportion of resistant variants in a population, or the effect on practical field performance of the pesticide is not involved.
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From page 299... ...
These are done either to gain initial or "baseline" sensitivity data before the widespread commercial use of a new pesticide or, more commonly, to examine individual cases of suspected resistance indicated by obvious loss of field efficacy of the product. Thus, monitoring can be used to indicate either continuous surveillance or ad hoc testing programs; this double use is acceptable, providing the meaning of the term is made clear in any particular context.
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From page 300... ...
The use of the above terms as suggested by FRAC, however, can also be misleading: resistant forms found in the field in low numbers or with a low degree of resistance or fitness are certainly field and not laboratory resistant, yet such forms may not be affecting practical control. Whatever terms are selected there is no substitute for defining clearly the implications and limits of their use in all publications.
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From page 301... ...
, or where a range of variants with different degrees of resistance arise and resistance tends to build up in a stepwise manner (as in the resistance of powdery mildews to 2-aminopyrimidine and triazole fungicides)
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From page 302... ...
Such has been the case with certain combinations of fungicides and plant pathogens, for example, the use of dimethirimol against cucumber powdery mildew (Sphaerotheca juliginea) in Holland (Brent, 1982)
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From page 303... ...
. ,~ ~ slgnlrlcance or resistance Subsequently Check rate of spread or decline of resistance Assess risk Decide strategy of use Work the decided use strategy Watch practical performance closely If resistance problem is confirmed, review strategies and modify Study cross-resistance, hltness of variants and other factors affecting impact of resistance Watch performance, review strategies SOURCE: Brent (unpublished)
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From page 304... ...
Surveys should be started early, however, by testing field samples of each major target pest for degrees of sensitivity under controlled conditions before the chemical is used extensively (Table 11. Such testing provides valuable initial sensitivity (or baseline)
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From page 305... ...
containing the target organism throughout a region or country are examined, and one or a few representative samples of the population are taken at each site. At the extreme, area populations of insects or spores can be trapped by using suction traps for aerial populations of insects or by mounting test plants on a car top and driving through a cropping area to sample the powdery mildew spore population (Fletcher and Wolfe, 1981~.
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From page 306... ...
has drawn together details of tests against 20 important pests, published at intervals since 1969 in the FAO Plant Protection Bulletin; more recent issues of the bulletin contain new or updated procedures. Recommended methods for testing fungicide resistance in crop pathogens have also been published by FAO (1982)
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From page 307... ...
Global programs have been organized by WHO to survey insecticide resistance in anopheline mosquitoes (WHO, 1976, 1980) and by FAO to survey insecticide resistance in pests of stored grain (Champ and Dyte, 1976)
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From page 308... ...
In the former cases monitoring tended to follow reports of loss of control and results were obtained too late to permit any management strategy other than withdrawal of the product, but in the latter, where monitoring preceded any major breakdown in performance, avoidance strategies either were already operating or were introduced following the results of monitoring. Since the early 1970s the incidence of triazine-resistant biotypes of various weeds in different crops has been monitored extensively in different parts of the United States, mainly by collecting seeds and growing progeny for glasshouse tests.
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From page 309... ...
Conferences are helpful, but the international courses on fungicide resistance organized by Professor Dekker and colleagues and held at Wageningen and more recently in Malaysia- have proved particularly useful, since they included laboratory sessions and a tactical exercise in addition to lectures and group discussions. Perhaps similar courses could be organized on insecticide and herbicide resistance.
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From page 310... ...
Pp. 219-230 in Fungicide Resistance in Crop Protection, J
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From page 311... ...
1984. Sensitivity of barley powdery mildew to systemic fungicides in the UK.
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From page 312... ...
1984. Resistance to inhibitors of sterol biosynthesis in cucumber powdery mildew.
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