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1.
Dicarboximide resistance in Botrytis cinerea in protected lettuce   总被引：2，自引：5，他引：2  
In surveys of protected lettuce crops in the Humberside area of the UK during 1984-5, 47.3% of Botrytis cinerea isolates were resistant to dicarboximides and 25% to benomyl. Dicarboximide-resistant isolates obtained direct from the field had a moderate degree of resistance with ED50 values for mycelial growth on agar of 1.0-2.4 μg/ml vinclozolin for all except two of 30 isolates.
Isolates which were resistant to vinclozolin were also resistant to iprodione, myclozolin and procymidone. Thirty dicarboximide-resistant isolates obtained direct from the field were capable of infecting cucumber cotyledons sprayed with field-strength Ronilan (250 μg/ml vinclozolin) whereas sensitive strains were not. Strains showing different degrees of resistance to dicarboximides developed after incubation of sensitive and resistant strains on agar supplemented with vinclozolin. Some of these strains had ED50 values for mycelial growth on agar of more than 100 μg/ml vinclozolin. No highly resistant isolates were obtained direct from the field. Resistance to dicarboximides in field isolates was stable.  相似文献   

2.
Fourteen single-spore cultures of benomyl-resistant Venturia pirina were isolated from pear scab lesions at four sites in Israel. According to the ability of the isolates to germinate and grow at varying benomyl concentrations, four levels of resistance were determined in vitro : three isolates with low resistance (LR) grew at 0.5 but not at 5 μg/ml benomyl: five moderately resistant (MR) isolates grew at 5 but not at 50 μg/ml benomyl: five highly resistant (HR) isolates grew at 50 μg/ml but their hyphae were curled: and one isolate with very high resistance (VHR) grew unaffected at 50 μg/ml benomyl. The difference between the HR and the VHR phenotypes was clearly shown on medium amended with N -(3.5-dichlorophenyl) carbamate (MDPC): only the VHR isolate showed negative cross-resistance to 1 μ g/ml MDPC. whereas HR isolates grew unaffected. Crosses between resistant isolates and sensitive wild types, as well as between different resistant isolates, showed that the various levels of resistance are conferred by four allelic mutations that constitute a polymorphic series at a single locus.  相似文献   

3.
Amongst 489 mass isolates of Botrytis cinerea obtained from protected crops in Humberside during 1989, 67.3% were resistant to benomyl and 45.6% to vinclozolin. Two isolates resistant to dichlofluanid were obtained with EC50 values for mycelial growth on agar of 21.45 and 19.78 μg dichlofluanid/ml, respectively, compared with values of 1.55-2.56 μg/ml for sensitive isolates. EC50 values for germ tube emergence and length were much lower than for mycelial growth. In population studies carried out on tomatoes in a polythene tunnel, resistance to dichlofluanid and to vinclozolin declined over a 12-week period in the absence of fungicides. Field isolates of B. cinerea resistant to dichlofluanid were also resistant to vinclozolin. but strains resistant to dichlofluanid and sensitive to vinclozolin were obtained during population studies. Examination of a number of features of dichlofluanid-resistant strains revealed a degree of lack of fitness as compared with sensitive strains. There is no indication that resistance to dichlofluanid poses a great threat to the control of grey mould in Humberside at present.  相似文献   

4.
Mycelial isolates (115) of Pseudocercosporella herpotrichoides were obtained from five field sites in England. Carbendazim-resistant isolates were detected by their mycelial growth on agar containing 1 μg/ml carbendazim. Resistant isolates were found at two of the five sites examined and one of these had never been treated with benzimidazole fungicides. Amongst the carbendazim- resistant isolates there was a predominance of isolates with pale mycelium, an irregular colony margin and a relatively slow growth rate; however, this association was not absolute. Large differences in the effects of carbendazim on mycelial growth of sensitive and resistant isolates were demonstrated; growth of sensitive isolates was completely inhibited at 0.5 μg /ml carbendazim whilst five of the six resistant isolates examined grew on agar containing 1000 μg/ml fungicide. The carbendazim-resistant isolates were cross-resistant to benomyl, thiophanate-methyl and to a Icsser degree thiabendazole, but not to prochloraz. Conidia of carbendazim-resistant isolates were as resistant. Carbendazim-resistant isolates were just as pathogenic to wheat as sensitive isolates. The implications of these results and other reports of benzimidazole resistance in P. herpotrichoides are discussed in relation to disease control.  相似文献   

5.
Benzimidazoles were used successfully against gummy stem blight of cucurbits for only one growing season (1980). It was soon noticed in experiments in vivo that they were not effective against some isolates of the pathogen. In a survey during the 1981 crop season, 76 out of 102 isolates collected from 20 plastic greenhouses all over the main cucurbit-growing areas of Crete were resistant to benomyl. The average benomyl concentrations that reduced mycelial growth rates of seven resistant and seven sensitive isolates by 50% were 716 ± 49 and 1.2 ± 0.34μg/ml respectively. The average growth rate of resistant isolates was lower than that of sensitive isolates but there were no differences in spore production and spore germination. The pathogenicity of resistant isolates on young cucumber plants was lower than that of sensitive isolates. The application of benomyl, carbendazim, cypendazole and thiophanate methyl to young cucumber plants at the rate of 300μg a.i./ml 1 day before inoculation with 500 000 spores/ml of the resistant isolates did not affect the infection rate of the disease after 4 days. Sensitive isolates caused no onslight symptoms on similarly treated plants.  相似文献   

6.
Forty-nine greenhouses of vegetable crops were surveyed in southeast Spain at the beginning of the disease season in December 1992 to estimate frequencies of resistance to benzimidazoles, dicarboximides and N -phenylcarbamates (NPC) in B. cinerea . Out of 261 isolates collected, 28% were sensitive to both benzimidazoles and dicarboximides, 15% were benzimidazole-resistant and dicarboximide-sensitive, 8% were benzimidazole-sensitive and dicarboximide-resistant and 46% were benzimidazole- and dicarboximide-resistant. Resistance to benzimidazole, dicarboximide and N -phenylcarbamate was determined by measuring the ability of each isolate to grow in the presence of carbendazim, procymidone and diethofencarb fungicides respectively. Carbendazim- or procymidone- resistant isolates were found in all surveyed greenhouses. Three isolates were found with resistance to carbendazim, procymidone and diethofencarb collected in two adjacent greenhouses that were sprayed with the carbendazim and diethofencarb mixture. All other isolates were sensitive to the mixture because they were either sensitive to carbendazim and resistant to diethofencarb or vice versa. Fitness of 31 isolates of B. cinerea was determined in vivo by measuring their sporulation and lesion growth rate on leaf disks. No fitness costs were associated with resistance to iprodione (dicarboximide) and benomyl (benzimidazole). Isolates with EC50 values higher than 101 mg/L for benomyl and 1.6 mg/L for iprodione were considered to be field resistant (they caused visible lesions on cucumber leaf disks treated with each fungicide).  相似文献   

7.
In 1981 metalaxyl-resistant Phytophthora infestans was found in 44% of the 63 crops examined in south-west Scotland. In 1982, when fungicides containing acylalanines (metalaxyl or ofurace) were not used in the area, it was detected in 15%. Metalaxyl-resistant strains were found in several crops which had been sprayed only with non-acylalanine fungicides or had received no fungicidal treatment. In neither year was resistance associated with a significant breakdown of disease control.
Metalaxyl-resistant isolates of the blight fungus were obtained from tubers from crops in which resistance was detected on the foliage.
In detached leaf experiments, resistant isolates retained their ability to grow on leaves treated with 100 μg/ml of metalaxyl after 52 weekly transfers on untreated leaves, and produced sporangia on leaves treated with up to 2000 μg/ml of metalaxyl or ofurace. In mixtures with sensitive sporangia the proportions remained stable after nine weekly transfers on untreated leaves. However, at concentrations as low as 50 μg/ml, metalaxyl and ofurace reduced the extent of colonization and the numbers of sporangia produced by resistant isolates by an average of 50%.  相似文献   

8.
A technique is described for testing isolates of Septoria tritici from winter wheat for resistance to benzimidazole fungicides. Secondary spores from 23 isolates were tested on Czapek Dox V-8 agar amended with benomyl at 1–10 μg ml. Twenty-one isolates were recovered from eight crops in England in 1984 and two (PBI isolates) were obtained in 1973. Thirteen isolates, including both PBI isolates, were sensitive to benomyl at 1 μg ml?1 and nine were resistant at 10 μg ml?1. The remaining isolate had a low proportion (1:3.7 x 104) of resistant spores. The minimum inhibitory concentration for sensitive isolates was 0.2–0.4 μg ml 1 benomyl and for resistant isolates was more than 1000 μg ml 1. Benomyl-resistant isolates were cross-resistant to carbendazim, thiabendazole and thiophanate-methyl, but not to 12 other fungicides with different modes of action. The implications of these findings are discussed.  相似文献   

9.
A critical test of fungicidal activity against the wound pathogen Glomerella cingulata f.sp. camelliae on camellias involved the application of a conidial suspension to scratches on detached leaves, treated with fungicide 24 h previously. In this test, prochloraz at 250–500 μg/ml a.i. in both EC and manganese WP formulations was highly effective, inhibiting leaf rotting by 90–100% compared with 55% or less in some tests with benomyl, chlorothalonil and captafol at 500–1000 μg/ml and captan at 1200 μg/ml. Prochloraz gave similar protection to leaves when applied to whole plants. Protection was less, especially on older leaves, when wounding and inoculating were delayed by 7 or more days after treatment. Prochloraz did not prevent all infection through comparatively large wounds, e.g. leaf scars, made on stems 24 h after treatment.
Poor control of the disease in a nursery was not due to resistance of the pathogen to benomyl; in vitro tests failed to detect full resistance at this time. Under nursery conditions a statutory policy of destroying infected plants and spraying the remainder with prochloraz or prochloraz manganese (both at 500 μg/ml), alternating with benomyl (500 μg/ml) on a weekly basis apparently prevented spread of the disease to healthy plants.  相似文献   

10.
A total of 568 B. cinerea isolates were collected from diseased sweet basil plants and the air in 10 sweet basil greenhouses. Mycelial growth tests were used to evaluate the sensitivity of these isolates to benomyl, fenhexamid, iprodione, polyoxin AL and pyrimethanil. EC50 values for polyoxin, the main botryticide on sweet basil in Israel, ranged from 0.4 to 6.5 μg ml?1 and had a bimodal distribution; the EC50 values for sensitive isolates ranged from 0.4 to 1.5 μg ml?1 and the EC50 values for low-level resistant isolates ranged from 4 to 6.5 μg ml?1. Among populations that had not been exposed to polyoxin treatments, 20 to 35 % of the collected isolates were low-level resistant for polyoxin. Polyoxin treatments in an experimental greenhouse shifted the equilibrium in favour of low-level resistant isolates, and the change occurred rapidly: from a frequency of 20 % low-level resistant isolates in the population that had never been treated with polyoxin to a frequency of 72 % after a few treatments over two seasons. Prolonged use of polyoxin in Israeli basil crops (in some sites for more than 10 years) does not appear to have led to the development of high-level resistance, but low-level resistant isolates were found in commercial greenhouses with the frequency of up to 73 %. High-level resistance to benzimidazoles was common (60 to 80 % of isolates) in greenhouses with a history of benzimidazole treatments; whereas 15–25 % of the isolates from greenhouses in which fungicides were not used were resistant. Low-level resistance to dicarboximides was fairly widespread (frequency of 30 to 80 % depending on the greenhouse) and a few cases of moderate resistance to dicarboximides were also noted (frequency of 0 to 9 %). Neither high- nor low-level resistance to anilinopyrimidines was common in sweet basil commercial greenhouses (0 to 7 %). However, 34 % of the isolates were strongly resistant in the experimental greenhouse, following a few treatments with anilinopyrimidine fungicides during the previous season. Before those treatments, the proportion of anilinopyrimidines resistant isolates had been 1 %. About 3 % of the isolates exhibited low-level resistance to fenhexamid and no isolates were found to be strongly resistant to fenhexamid. Low-level resistance to one fungicide was often associated with low-level resistances to other fungicides. Thirty-two phenotypes exhibiting resistance to one or more of the tested fungicides were noted among B. cinerea isolates. Resistant isolates showed similar or reduced fitness parameters in comparison to wild-type isolates.  相似文献   

11.
The sensitivity of four fungal antagonists (Chaetomium globosum, Trichoderma harzianum, T. viride, Trichoderma sp.) to six fungicides was evaluated. The fungi were insensitive to captan, mancozeb and thiram but were sensitive to benomyl (EC50 < 0 3/μg/ml) and the two dicarboximides iprodione and procymidone (EC50 < 3 3/μg/ml). Conidia and mycelia of the four fungi were exposed to a series of ultraviolet irradiations in order to select biotypes resistant to benomyl and iprodione. Resistance to benomyl was not induced but a number of biotypes of each fungus were isolated from irradiated cultures that showed resistance to iprodione (EC50 values of up to 56·4, 177·8, 171·5 and 216·4/μg/ml for Chaetomium globosum, Trichoderma harzianum, T. viride and Trichoderma sp., respectively). With three exceptions, all selected biotypes retained their fungicide-resistance after being extensively cultured on fungicide-free medium. In general, growth of the fungicide resistant biotypes on MEA plates and in MYE liquid medium was equal to that of the corresponding wild-type strains. One resistant biotype of Trichoderma sp. (C62UV3) grew significantly (P < 0·05) better both on solid and in liquid medium. This resistant biotype was also observed to have greatly enhanced conidial production on agar plates. All fungicide resistant-biotypes retained the ability to antagonize the pathogen Sclerotium cepivorum in dual culture and, in two instances (A53UV1, A53UV5), exhibited greater antagonism as evidenced by the production of larger inhibition zones. Similarly, with two exceptions, the resistant biotypes retained the ability to control onion white rot disease caused by S. cepivorum in the glasshouse. In particular, two fungicide-resistant biotypes (Trichoderma sp. C62UV3 and Chaetomium globosum A53UV1) reduced white rot of onion more effectively than did their respective wild-type parents.  相似文献   

12.
A total of 651 isolates of cucumber corynespora leaf spot fungus ( Corynespora cassiicola ) collected from cucumber in Japan, either with (438 isolates) or without (213 isolates) a prior history of boscalid use, were tested for their sensitivity to boscalid by using a mycelial growth inhibition method on YBA agar medium. Additionally, seven isolates of C. cassiicola obtained from tomato, soybean, eggplant (aubergine) and cowpea in different locations in Japan were tested before boscalid registration. Minimum inhibitory concentration (MIC) and 50% effective concentration (EC50) values for 220 isolates from crops without a prior history of boscalid use ranged from 0·5 to 7·5 μg mL−1 and from 0·04 to 0·59 μg mL−1, respectively. Two hundred and fourteen out of 438 isolates collected from ten cucumber greenhouses in Ibaraki Prefecture, Japan, which received boscalid spray applications showed boscalid resistance, with MIC values higher than 30 μg mL−1. Moreover, resistant isolates were divided into two groups: a moderately resistant (MR) group consisting of 189 isolates with EC50 values ranging from 1·1 to 6·3 μg mL−1, and a very highly resistant (VHR) group consisting of 25 isolates with EC50 values higher than 24·8 μg mL−1. MR isolates were detected from all ten greenhouses, but VHR isolates were detected from only three. As a result of fungus inoculation tests which used potted cucumber plants, control failures of boscalid were observed against resistant isolates. Efficacy of boscalid was remarkably low against VHR isolates in particular. This is the first known report on boscalid resistance in Japan.  相似文献   

13.
Pre-harvest fungicidal treatments aimed at reducing inoculum levels in the field include copper oxychloride and benomyl. Pre-harvest applications of benomyl are currently restricted if used on fruit destined for certain export markets. Isolates of Colletotrichum gloeosporioides collected during a three-year market survey were used to determine the incidence of resistance to benomyl, thiabendazole and prochloraz using an in vitro assay. A total of 17.7% of all isolates tested were resistant to benomyl, of which 8.5% were highly and 9.2% moderately resistant. Isolates from certain production areas were less sensitive to benomyl and thiabendazole, and mango isolates were generally more sensitive than avocado isolates. No isolates were resistant to thiabendazole or prochloraz.  相似文献   

14.
In 1986, samples from 109 winter wheat crops in England and Wales were examined for benomyl resistance in Fusarium species. Of the 704 isolates obtained, 581 were identified as Fusarium nivale, of which 92.1 % were resistant to benomyl. Of the remaining isolates, 82 were identified as F. avenaceum, 40 as F. culmorum and one as F. poae; none of these isolates were resistant to benomyl. The vast majority of isolates of Fusarium spp. were obtained from superficial nodal or internodal lesions on the stems.  相似文献   

15.
Plots in two vineyards in the Golan Heights, Israel were treated with six botryticides during three growing seasons with 3 applications per season. Applications of fenhexamid, pyrimethanil and cyprodinil + fludioxonil were effective, resulting in 52–65% and 53–63% mean reduction in grey mould incidence and severity, respectively. Carbendazim, fluazinam and iprodione were ineffective or slightly effective. Five hundred and sixteen B. cinerea isolates were collected from infected berries or trapped from the air in the vineyards, and profiles of sensitivity to benomyl, fenhexamid, fluazinam, fludioxonil, iprodione and pyrimethanil were established for each of the isolates based on a mycelial growth test. Seventy-four percent of the isolates were sensitive to the six tested fungicides, and the other 26% of the isolates were classified into 10 phenotypes characterized by resistance to one or more fungicides. Resistant isolates showed fitness parameters similar or reduced in comparison to sensitive isolates. Resistance to benzimidazoles and to dicarboximides was the most frequent (up to 25%) and apparently pre-existed in the populations tested. Increased frequency of benzimidazole resistance, but not dicarboximide resistance, was observed following the 3 years of applications of the fungicides. High level resistance to pyrimethanil was present at a frequency of about 2% in both vineyards in the first 2 years of the sampling survey and reached 10% in the third year at Site 2. A few isolates were resistant to fenhexamid or fludioxonil (0.8 or 0.2%, respectively). No strong resistance to fluazinam was detected, although numerous, less sensitive isolates, presumably possessing multi-drug resistance traits, were recovered at higher frequency from the plots treated with fluazinam than from the untreated plots.  相似文献   

16.
In a survey conducted during 1991–1992, single-spored isolates of the eyespot fungus from the Swartland area were characterized and tested for sensitivity to carbendazim and ergosterol inhibiting fungicides. The 100 isolates tested were all fast growing, even marginate, and designated as Ramulispora herpotrichoides . Fungal growth was completely inhibit on PDA amended with carbendazim (1 μg/ml), indicating that the local population of the fungus is still at baseline sensitivity to benzimidazoles. The mean concentration of prochloraz calculated to inhibited growth by 50% (IC50 value) was 0.043 ± 0.029 μg/ml, which is comparable with the baseline sensitivity reported for European isolates. Of the 36 representative isolates screened against 2 μg/ml triadimenol, 44% were sensitive, while 36% were resistant. The triadimenol-resistant isolates were sensitive to propiconazole and flusilazole. However, four of the triadimenol-resistant isolates were also resistant to tebuconazole. These results indicate that South African isolates of R. herpotrichoides are sensitive towards carbendazim, prochloraz, propiconazole and flusilazole. They were found to differ, however, in sensitivity towards triadimenol and tebuconazole, where some isolates had an IC50 value greater than 2 μg/ml.  相似文献   

17.
Isolates of Botrytis cinerea resistant to benzimidazoles (BenR), dicarboximides (DicR), or both (BenR DicR) were found on table grapes in vineyards in Israel. In vineyards treated for one or two seasons with benomyl and dicarboximides, 41% of the isolates were benomyl-resistant, 18% were dicarboximide-resistant and 21 % were resistant to both fungicides. The frequency of resistant strains was very low in non-treated vineyards. Negatively correlated cross resistance (NCCR) was manifested by 46 BenR isolates which were sensitive to isopropyl N -(3,4-diethoxyphenyl) carbamate (NPC) and 73 benomyl-sensitive (Bens) isolates which were insensitive to NPC; NCCR was not influenced by sensitivity to dicarboximides. A mixture of Bens DicR plus BenR Dics isolates, inoculated on rose petals, was inhibited by mixtures of benzimidazoles plus NPC but not by benomyl, NPC or iprodione alone. Grey mould, incited on maturing grape berries by a vineyard population composed of Bens and BenR strains, was not controlled by benomyl, while the mixture of NPC plus carbendazim was effective.  相似文献   

18.
In winter/spring 1984 resistance to metalaxyl developed in Phytophthora infestans within tomato greenhouses in Preveza, Greece. The appearance of resistant isolates followed continuous applications of metalaxyl and prevalence of weather conditions favourable for late blight. The majority of resistant isolates grew on tomato leaf discs floated on solutions containing 100 μg/ml metalaxyl whereas sensitive isolates were inhibited at concentrations of 0.1 μg/ml.
In trials within polyethylene tunnels metalaxyl had no effect on the development of the late blight induced by resistant strains but both a mixture of this fungicide with mancozeb and mancozeb alone, gave satisfactory control of the disease when applied in a 7-day schedule.  相似文献   

19.
依据鉴别浓度检测了中国不同地理来源的114株草坪草币斑病菌对甲基硫菌灵的敏感性,并采用菌丝生长速率法测定了供试菌株对异菌脲和丙环唑的敏感性。结果显示:对甲基硫菌灵敏感的菌株共98株,占总数的85.96%,抗性菌株16株,占总数的14.04%;在8个有甲基硫菌灵施药历史的采样点中,5个点检测到了抗性菌株。异菌脲和丙环唑对草坪草币斑病菌的EC50值分别在0.012 1~1.264 4和0.000 4~0.100 4 μg/mL之间,平均EC50值分别为（0.525 6 ± 0.207 7）和（0.015 2 ± 0.020 1）μg/mL,最大EC50值和最小EC50值分别相差104.7和251.0倍。敏感性频率分布结果显示,币斑病菌对异菌脲和丙环唑已出现敏感性下降的亚群体。与从未施过相关药剂地区的币斑病菌群体相比,分离自8个有施药历史地块的菌株群体对异菌脲的敏感性均显著降低,4个有施药历史地块的群体对丙环唑的敏感性显著降低。相关性分析显示,对丙环唑最不敏感的10株币斑病菌对异菌脲的敏感性均呈现下降趋势,且两者间存在一定的正相关关系（ρ = 0.755 4,P < 0.000 1）,推测这部分菌株可能存在多药抗药性。本研究结果可为杀菌剂的合理使用及币斑病的有效防治提供理论支持。  相似文献   

20.
TwoPenicillium species, vizP. brevicompactum andP. corymbiferum, were isolated from senescent petioles of cyclamen and from bulbs of lilies, respectively, both samples treated previously with benomyl. The isolates turned out to be very resistant to this fungicide when grown on malt agar, supplied with the fungicide; at a concentration of 2000 g/ml they were less inhibited than randomly chosen isolates of the same species on agar with 1 g/ml.The strains retained their resistance at the same level for at least 3 months after repeated subculturing on fungicide-free agar.Resistance to benomyl coincided with resistance to methyl-thiophanate and, to a lesser extent, also to thiabendazole and furidazol.Samenvatting Uit afstervende bladstelen van cyclamen en uit schubben van leliebollen, welke eerder met benomyl waren behandeld, konden respectievelijkPenicillium brevicompactum enPenicillium corymbiferum worden geïsoleerd. De isolaten blekenin vitro zeer resistent tegen het fungicide. De myceliumgroei van deze isolaten werd op moutagar met 2000 g/ml benomyl minder geremd dan die van willekeurige isolaten van dezelfde soorten op agar met 1 g/ml (Fig. 1).De isolaten bleven gedurende tenminste 3 maanden resistent na regelmatig overenten op voedingsbodems zonder het fungicide.De resistente stammen van de beidePenicillium-soorten bleken eveneens resistent tegen methyl-thiophanaat en in mindere mate ook tegen thiabendazol en furidazol (Tabel 1). De volgorde van de groeiremmende werking van deze fungiciden was voor de willekeurig gekozen (gevoelige) isolaten: benomyl>thiabendazol>methyl-thiophanaat >furidazol. Voor de resistente stammen was deze: thiabendazol en furidazol >benomyl>methyl-thiophanaat. In het feit dat een dergelijke verandering in volgorde van remmend effect ook voorBotrytis cinerea geldt, ligt een aanwijzing, dat de wijze waarop de resistentie werkt, voor deze schimmels gelijk is.  相似文献   

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