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1.
Gray mold (Botrytis cinerea) is an important disease of grapevines (Vitis vinifera) and requires several fungicide treatments to achieve a satisfactory control in Chile. Furthermore, a high resistance risk has developed because of the extensive use of specific fungicides with a single-site mode of action. The aim of this study was to determine the presence of resistance to the multiple fungicides currently used against B. cinerea in Chile. During 2007–2009 and 2011, 214 isolates of B. cinerea from 36 commercial vineyards were examined for sensitivity to anilinopyrimidines (cyprodinil or pyrimethanil), demethylation inhibitors (DMIs) (tebuconazole), hydroxyanilides (fenhexamid) and phenylpyrroles (fludioxonil). Of all of the isolates, 62.7% were resistant to anilinopyrimidines, 7.2% to DMIs, 27.1% to hydoxyanilides and 44.8% to phenylpyrrole derivates. Overall, 16 (12.3%) of the isolates were sensitive; although none was resistant to all four of the fungicide classes, and 50 (38.5%), 51 (39.2%), and 13 (10.0%) isolates were resistant to one, two and three fungicides, respectively. In vitro, resistant isolates were capable of causing fruit rot on wounded apples pretreated with any one of the five fungicides at label concentrations. To the best of our knowledge, this is the first report of isolates having simultaneous resistance to anilinopyrimidines, DMIs, phenylpyrroles and hydroxyanilides in B. cinerea populations from grapevines in Chile. Therefore, fungicide resistance is a serious problem that questions the sustainability of the current gray mold control strategy, which relies almost exclusively on fungicides with single-site modes of action. 相似文献
2.
Cercospora beticola, causal agent of Cercospora leaf spot (CLS) of sugar beet, is primarily controlled by fungicides. Benzimidazole and demethylation inhibiting fungicides, including carbendazim and flutriafol, have been widely used in Serbia. Since these fungicide groups have a site-specific mode of action, there is a high risk for developing resistance in target organisms, which is the most important limiting factor in Cercospora leaf spot chemical control. A rapid identification of flutriafol and carbendazim resistance can help researchers in examining the potential of different fungicide resistance management practices, as well as in selection of fungicides for use in the areas where resistance has occurred. One hundred single-conidia isolates were collected from 70 representative locations of the sugar beet production region in Serbia. Evaluation of the isolates' sensitivity was based on the reduction of mycelial growth on medium amended with 1.25 μg mL−1 flutriafol and 5 μg mL−1 carbendazim. Resistance to flutriafol and carbendazim was detected in 16% and 96% of the tested isolates, respectively. All isolates resistant to flutriafol were resistant to carbendazim as well, which is the first report of a double resistance to fungicides in C. beticola. Detection of the isolates resistant to flutriafol and carbendazim using Cleaved Amplified Polymorphic Sequence (CAPS) markers confirmed the results of the in vitro tests. The efficacy of carbendazim, flutriafol, azoxystrobin, and tetraconazole at commercially recommended doses was evaluated in field trials where sugar beet plants in plots were inoculated with a mixture of isolates either sensitive and/or resistant to flutriafol and carbendazim. Carbendazim and flutriafol efficacy was very low in plots inoculated with isolates resistant to these fungicides. Presented results will contribute to development of a pathogen population sensitivity monitoring strategy that could be used for an effective CLS management in the region. 相似文献
3.
G. Skylakakis 《Crop Protection》1982,1(3):249-262
The importance of resistance has increased in the last decade, together with the increasing use of site-specific fungicides. Mathematical models have been developed to deal with disruptive selection that occurs when the initial population of the target organism in terms of fungicide sensitivity consists of two or more distinct, non-overlapping distributions around widely different central values. Whether these models are static or dynamic, they lead to the same basic conclusions as to what factors would accelerate resistance build-up, namely the initial incidence of the resistant mutants, the efficacy of the fungicide at risk and the degree of resistance to it, and the degree of control pursued in the field. Dynamic models add to those factors the speed of the pathogen spread in the field, the fitness of the resistant mutants and the size of the pathogen population exposed to the fungicide. Resistance build-up can be delayed by the use of mixtures. In such a case, the higher the efficacy of the companion fungicide, the greater the delay. Alternation of fungicides will delay resistance build-up in calendar time: however, in the case of fit resistant mutants it will not extend the useful life of the fungicide at risk. No models have been developed to deal with the directional selection that occurs when, in terms of fungicide sensitivity, the population of the pathogen consists of one wide unimodal frequency distribution. Further research is recommended towards verifying the disruptive selection models, creating models to deal with directional selection and generating baseline sensitivity data for new fungicides before their commercial introduction. 相似文献
4.
Field strains of Botryotinia fuckeliana were isolated from diseased grape berries which were collected at the harvest, between 1993 and 1997, from French vineyards located in Alsace, Armagnac, Bordeaux, Champagne and Loire Valley. According to the inhibitory effects of fungicides towards spore germination, germ-tube elongation and mycelial growth, several phenotypes could be characterized. Thus, two types of benzimidazole (e.g. carbendazim, thiabendazole)-resistant strains were detected; negative cross-resistance towards diethofencarb, diphenylamine and dicloran was found only in one type. Most dicarboximide (e.g. iprodione, procymidone, vinclozolin)-resistant strains were also weakly resistant to aromatic hydrocarbon fungicides (e.g. chloroneb, dicloran, tolclofos-methyl) but remained sensitive to phenylpyrroles (e.g. fenpiclonil, fludioxonil). However, in some other dicarboximide-resistant strains, resistance was observed either as being restricted to dicarboximides or as extending weakly to phenylpyrroles. Towards anilinopyrimidines (e.g. cyprodinil, mepanipyrim, pyrimethanil), three resistant phenotypes have been identified. In the most resistant one, resistance was restricted to anilinopyrimidines, whereas in the others, resistance extended to various other groups of fungicides including dicarboximides, phenylpyrroles, sterol biosynthesis inhibitors (e.g. tolfanate, prochloraz, tebuconazole) and the hydroxyanilide derivative, fenhexamid. According to the pattern of cross-resistance, two phenotypes were characterized within these multifungicide-resistant strains. In vitro tests conducted with fenpropimorph, fenpropidin and spiroxamine, revealed the existence of strains highly susceptible to these sterol Δ14- reduction inhibitors. This property was correlated with a decreased sensitivity towards fenhexamid. 相似文献
5.
This work determined the sensitivity of field populations of Sclerotinia sclerotiorum (Lib.) de Bary before exposure to the fungicide fludioxonil (= baseline sensitivity) and assessed the risk of fludioxonil resistance. The mean EC50 (Effective Concentration) and Minimum inhibitory concentration (MIC) values for fludioxonil based on inhibition of mycelial growth of 120 wild-type isolates were 0.015 ± 0.005 μg/ml and <0.05 μg/ml, respectively. Positive cross-resistance was not detected between fludioxonil and benzimidazole fungicides but was detected between fludioxonil and dicarboximide fungicides which are considered as high resistance risk fungicides by FRAC, even though these fungicides have different molecular structures. By growing wild-type isolates on potato dextrose agar (PDA) containing sublethal concentrations of the fungicide, we obtained four fludioxonil-resistant mutants with resistance factors (EC50 resistant/EC50 sensitive phenotypes) >2000. The laboratory fludioxonil mutants were less fitter than their parental isolates in terms of mycelial radial growth, pathogenicity and sclerotial production. Moreover, on PDA amended with NaCl, the laboratory fludioxonil mutants grew more slowly than their fludioxonil-sensitive parents, especially at lower concentrations of NaCl. According to the fitness of mutants and the cross-resistance between fludioxonil and dicarboximide fungicides, phenylpyrroles can be considered to pose a moderate resistance risk. In a field trial, fludioxonil provided greater control (over 90% disease control) of S. sclerotiorum than iprodione. 相似文献
6.
Early blight, caused by the fungus Alternaria solani and brown leaf spot, caused by Alternaria alternata, are important diseases of potato crops in Idaho. In recent years growers have reported a reduction in efficacy of fungicides traditionally used in the past decade to control early blight. In 2009, a collection of A. solani 39 isolates were screened for resistance to azoxystrobin, pyraclostrobin, boscalid and famoxadone. Fungicide sensitivity testing was done using spiral plate dilution gradients. Results showed that of 39 isolates screened, all were resistant to azoxystrobin and three were resistant to boscalid. None were resistant to pyraclostrobin or famoxadone. In summer 2010, more isolates were collected (9 A. alternata and 26 A. solani) and the survey was expanded to include more fungicides with four different modes of action that targeted succinate dehydrogenase (SDH), methionine biosynthesis, mitochondrial respiration and multi-site contact activity. New isolates of A. solani and A. alternata were also collected from two additional sites. The results showed that 57% of the isolates were resistant to boscalid as well as an average of 63% of the isolates being resistant to the strobilurin fungicides. Seven and 15% of isolates were resistant to penthiopyrad (an SDH inhibitor), and pyrimethanil (a methionine biosynthesis inhibitor), respectively. However, none of the isolates were resistant to fluopyram (an SDH inhibitor) or a mixture of fluopyram and pyrimethanil. Although there appears to be cross resistance developing in Alternaria spp. to some of the new SDH inhibitors like penthiopyrad, others such as fluopyram are still showing limited to no resistance development in Alternaria spp. in Idaho. 相似文献
7.
A range of fungicides were evaluated for control of anthracnose (Colletotrichum lupini) in lupin. Glasshouse investigation identified fungicides that reduced disease severity with varying degrees of efficacy. When applied 1 d prior to infection, azoxystrobin, chlorothalonil, mancozeb and copper oxychloride fungicides were highly effective. Systemic fungicides such as tebuconazole, benomyl and carbendazim were less effective. Application timing was important; fungicides such as chlorothalonil and mancozeb were less effective when applied 5 d prior to infection compared with 1 d prior. Application after infection was ineffective for all fungicides. In field experiments application of azoxystrobin, mancozeb or chlorothalonil during flowering and podding reduced incidence of anthracnose infection on pods. Yield responses occurred in moderately susceptible, moderately resistant or resistant cultivars. Seed infection was reduced but not eradicated. Application of foliar fungicides for anthracnose control is potentially a viable management option for lupin production in high anthracnose risk areas of Western Australia. 相似文献
8.
《Crop Protection》1988,7(1):16-19
Two types of strains of Ustilago nuda, resistant to carboxin and fenfuram, were detected on winter barley crops in 1986. The most frequent strains are similar to those found previously and they are characterized by their great susceptibility to mepronil and flutolanil. This negative correlation between two groups of carboxamide fungicides is not found when the other type of carboxin-resistant isolates is considered. From these observations, we elaborate a simple teliospore-germination test which can be used for routine survey of resistance. In field trials, when the resistant strains are prevalent (in the absence of treatment), the efficacy of seed dressings with carboxin or fenfuram against barley loose smut is low. In such situations, which are common with the winter barley varieties Panda or Viva, inhibitors of sterol biosynthesis such as flutriafol or triadimenol remain very active in practice. 相似文献
9.
A total of 134 Czech Pseudoperonospora cubensis isolates originating from Cucumis sativus were used for fungicide resistance screening. Efficacy of six commonly used and registered fungicides was screened in Czech P. cubensis populations. The investigations covered the frequency and occurrence of sensitive, moderately resistant and resistant isolates to the individual fungicides during the period 2005–2010. Fosetyl-Al (Aliette 80 W) and propamocarb (Previcur 607 SL) were the most effective fungicides. All tested isolates were sensitive on all tested fosetyl-Al concentrations. However, some isolates expressed resistance (profuse sporulation) or moderate resistance (limited sporulation) to lower and/or even to recommended concentrations of propamocarb in the years 2006 and 2008–2010. Metalaxyl (Ridomil PLUS 48 WP) and metalaxyl-M (Ridomil Gold MZ 68 WP) were ineffective. Isolates collected in 2008 and 2009 showed large variation in moderate resistance or resistance even at high fungicide dosages. However, this result was not confirmed in 2010, when efficacy of these fungicides increased slightly, and 69% and 43% of isolates were controlled at the recommended concentration of metalaxyl-M and metalaxyl, respectively. Limited or profuse sporulation was observed only sporadically at high concentrations. Sensitivity of isolates to cymoxanil (Curzate K) differed among the studied years. While cymoxanil was ineffective in the years 2005–2008 and in 2010, 68% of isolates were controlled at the recommended concentration in 2009. During the years 2005 through 2010, a shift towards higher sensitivity to dimethomorph was observed at all screened concentrations. 相似文献
10.
The dicarboximides (iprodione, procymidone, vinclozolin) are a relatively new group of protectant fungicides which are used mainly for the control of Botrytis cinerea Pers. The literature documenting the emergence of dicarboximide-resistant Botrytis strains and the current situation, is reviewed. Although dicarboximide-resistant Botrytis can be produced readily in the laboratory, extensive monitoring did not reveal the emergence of such strains in the field until after 2–3 years of intensive use of dicarboximides. Today, resistant strains are foubd in many areas where the dicarboximides have been in constant use. Nevertheless, loss of control by these fungicides has not, so far, become a major field problem, possibly because of a loss of vigour and pathogenicity that is often linked to dicarboximide resistance in Botrytis strains. Because resistant strains also produce varying numbers of sensitive conidia, such strains are rapidly resensitized in the absence of dicarboximide fungicides. These findings suggest that the nature of dicarboximide resistance is quite different to that of carbendazim resistance, in that carbendazim-resistant Botrytis strains show no loss of vigour and are, moreover, very stable. 相似文献
11.
M. W. Shaw 《Crop Protection》1989,8(6):405-411
Several authors have discussed the evolution of fungicide resistance in a pathogenic fungus which contains a distinct resistant genotype to one fungicide (A), but not to another (B). Each author predicts when alternating use of the two fungicides will retard the evolution of resistance to A more than use of a mixture, but their conclusions differ. This is partly because they use in different ways the concept that the fungicides act independently in the mixture. A parameter ψ is introduced that quantifies the extent to which component B modifies the evolution of resistance to A. If admixture of B has no effect, ψ = 1 and A and B are independent with respect to the development of resistance. ψ is defined as the ratio of the change in frequency of the resistant genotype when a mixture of A and B is applied for a given time, to the change when A is applied alone. It is useful for interpreting the results of experiments and the predictions of mathematical models. Small values of ψ indicate mixtures that greatly retard the evolution of resistance. These are more likely to occur if fungicides, with the other properties assumed, act at the same stage of the life cycle of the fungus. Values <0·5 indicate that mixtures will be more favourable than alternation in the absence of cross resistance. 相似文献
12.
13.
Occurrence of resistant strains of Botrytis cinerea to anilinopyrimidine fungicides in table grapes in Chile 总被引：1，自引：0，他引：1
Effort to control gray mold caused by Botrytis cinerea failed in a table grapevine (Vitis vinifera) vineyard near Santiago, Chile where cyprodinil (Vangard 50 WP), a new fungicide of the anilinopyrimidine group, had been applied alone up to four times per year during two growing seasons. A relatively high frequency (38.5%) of resistant isolates of B. cinerea (EC50 for mycelial growth inhibition varied from 2.9 to 4.84 μg ml−1) may explain the partial loss of field control efficacy obtained. Resistance was correlated with a complete loss of in vivo sensitivity to cyprodinil. Resistant isolates of B. cinerea showed cross resistance to the anilinopyrimidines fungicides mepanipyrim and pyrimethanil. Cyprodinil partially impaired conidia germination and differentially affected conidial germination of resistant and sensitive isolates. Significant differences (p<0.05) in growth rate, sclerotia production and osmotic sensitivity were found among isolates of B. cinerea, but no correlation could be drawn between these biological differences and resistance or sensitivity. This indicates a disruptive selection characteristic of monogenic resistance. Thus, strategies were implemented to avoid the further development and spread of resistance in B. cinerea to the anilinopyrimidine fungicides. To our knowledge this constitutes the first mention of resistance in B. cinerea populations to anilinopyrimidine fungicides in South America. 相似文献
14.
15.
江淮地区是我国重要的小麦产区之一。为明确该地区麦田日本看麦娘对精噁唑禾草灵的抗性情况,采用整株水平生物测定法检测了该地区的10个种群对精噁唑禾草灵的抗性水平;扩增和比对了高抗种群(AH-40、JS-19)、中抗种群(AH-41、JS-20)与敏感种群(AH-7)的ACCase CT区域基因片段差异,并测定了GSTs、P450s酶抑制剂对精噁唑禾草灵的增效作用及4个抗性种群对8种除草剂的抗性。结果表明,高水平抗性种群数量占供试种群总数的50%,抗性指数为13.14～18.54;测序结果表明,高抗和中抗种群中均未发现已报道可引起靶标抗性的位点突变。AH-40种群在施用GSTs代谢酶抑制剂(灭草环、三聚氯氰、NBD-Cl)和P450s酶抑制剂(PBO、马拉硫磷)后均可显著提高其对精噁唑禾草灵的敏感性,增效倍数分别为1.68、1.68、2.45、1.64、2.03;JS-19种群在施用GSTs酶抑制剂(灭草环、三聚氯氰、NBD-Cl)后GR50有所下降,增效倍数为1.71、1.94、1.71;供试酶抑制剂未对其他抗性种群产生明显增效作用。抗性检测结果显示,4个抗性种群均对... 相似文献
16.
《Crop Protection》1986,5(5):299-305
The way in which fungal populations respond to fungicides used for their control, and hence the risk of disease control failures due to resistance, depends primarily on the type of genetic variability available. Existing evidence indicates that the type of variability differs with the chemical rather than with the organism. With most systemic fungicides and antifungal antibiotics, high resistance can be obtained by mutation of a major gene. The population response is then qualitative and a high or moderate resistance risk is involved, depending on the effect of the major gene on fitness. Mathematical models are available, on the basis of which the establishment of resistance and the loss of effectiveness of a fungicide of this group can be predicted. With a few systemics and some protectants, a practically significant decrease of sensitivity requires the interaction of several genes, each of a rather minor effect: the response is quantitative and the resistance risk is low th moderate. In this situation, the combination of degree of resistance and fitness loss varies greatly and this has not permitted the construction of suitable mathematical models so far. Finally, there is no evidence that pathogenic fungi possess genes for resistance to most protectant fungicides, which involve a low resistance risk, if any. Selection of forms less sensitive to fungicides of this group does not seem to have taken place, in spite of many years of repeated use. 相似文献
17.
Baseline sensitivity to fungicides was determined in 105 Plasmopara viticola isolates using the floating leaf disk test. The mean EC50 values were 0.372 ± 0.104, 0.604 ± 0.215, 0.306 ± 0.101, and 0.922 ± 0.209 μg mL−1 for fluxapyroxad, benthiavalicarb-isopropyl, ametoctradin, and famoxadone, respectively, which we regarded as the baseline sensitivity to the four fungicides. Resistant mutants can be generated using a median effective concentration or a minimum inhibitory concentration to fluxapyroxad, benthiavalicarb-isopropyl, ametoctradin, and famoxadone respectively, but the resistance stability of resistant mutants from the minimum inhibitory concentration (MIC) was significantly lower than that from the median effective concentration (EC50). In brief, high resistant mutants obtained was at the higher concentration, the resistance stability of the mutants recovered was more quickly. But lower resistant mutants obtained was at the lower concentration, the resistance stability of the mutants recovered was slower. Even if the resistance level of the mutants is low, it is more capable of stably heritable. These data indicate that the highest dosage is not used, resistance will still develop. In a correlation analysis, no cross-resistance to each other of these four fungicides was observed. 相似文献
18.
Potato late blight caused by the oomycete Phytophthora infestans is a devastating disease of potato worldwide. Most of the potato cultivars grown in conventional agriculture are susceptible, or at best moderately resistant, and require frequent applications of fungicides to avoid heavy yield losses.In field trials spanning four years, we have investigated the effect of potassium phosphite, an inorganic salt on potato late blight. Potassium phosphite is known to induce defence responses in potato and to also have direct toxic effects on oomycetes, which in turn counteract late blight and tuber blight development. However, the use of this salt is not yet implemented and approved in European potato cultivation. We compared the effect of phosphite alone with fungicides currently used in Swedish potato cultivation. We also investigated the combined use of potassium phosphite and reduced doses of fungicides. Table potato cultivars and starch potato cultivars with different levels of resistance were used.We found that potassium phosphite in combination with reduced doses of fungicides results in the same level of protection as treatments with the recommended full dose of fungicides. These combined treatments reduce the need of traditional fungicides and may also decrease the selection pressure for fungicide resistance development in the pathogen. In relatively resistant starch potato cultivars using phosphite alone gave sufficient protection against late blight. Furthermore, in starch potato a combination of phosphite and fungicides at two-week intervals provided similar protection to weekly applications of fungicide at the recommended dose. Foliar treatment with phosphite also gave protection against tuber blight at similar levels to that of the best-performing fungicide. Our data suggests that potassium phosphite could be used in potato cultivation in temperate regions such as in Sweden, at least in combinations with reduced rates of fungicides. The implementation of the use of phosphite in practical potato crop protection as part of an IPM strategy is discussed. Doses, intervals and combinations could be adjusted to the level of cultivar resistance. 相似文献
19.
The control of Botrytis cinerea and Plasmopara viticola, two of the most important parasites on grapevines, is achieved by using fungicides. Recently several highly active compounds have been introduced but with some of them, failures of disease control have been observed in French vineyards. These phenomena are due to the build-up of resistance to benzimidazoles (benomyl, carbendazim, thiophanate-methyl) or to di-carboximides (iprodione, procymidone, vinclozolin) in Botrytis cinerea and to phenylamides (metalaxyl, ofurace) in Plasmopara viticola. The characteristics of the various resistant strains (levels of resistance, patterns of cross-resistance, fitness) are described. In 1982 and 1983 there has been monitoring for resistance in most French vineyards: the tests used and the results with regard to the frequencies of resistant strains are discussed. 相似文献