Effects Of Carbendazim Research Articles

Effect of carbendazim and pencycuron on soil bacterial community

Soil bacterial composition is used as one of the important indicators of negative effects of the use of pesticides in agriculture. Very little is known on the effects of fungicides, particularly carbendazim and pencycuron on soil bacterial community. In this study, laboratory experiments were conducted to examine the effects of various concentrations of carbendazim and pencycuron on diversity of bacterial community in soils collected from strawberry field and incubated at different temperature conditions. The degradation rate of fungicides both in sterile and non-sterile soils were also investigated. Residues of fungicides were measured using high performance liquid chromatography (HPLC) and the change in bacterial community was examined by comparing the 16S rDNA bands on patterns by denaturing gradient gel electrophoresis (DGGE). The dissipation of carbendazim was affected by concentration applied, whereas that of pencycuron was affected by both concentration applied and incubation temperature. The microbial community could recover to its previous composition after 126 days of cultivation with the application of 10 mg/kg of carbendazim but not with the application of a high concentration, 100 mg/kg, of pencycuron. From cluster analysis, the bacterial community structure showed approximately 50% similarity throughout the experimental period, which indicated that the soil microbiota composition was not stable throughout the 120 cultivation days.

Effects of carbendazim on conidial germination and mitosis in germlings of Fusarium graminearum and Botrytis cinerea

The effects of carbendazim on carbendazim-sensitive (wild-type) and -resistant strains of Fusarium graminearum and Botrytis cinerea were compared. When treated with carbendazim, conidia and germlings of wild-type F. graminearum and B. cinerea germinated and grew to produce stunted, distorted, and abnormally branched germlings; in addition, distinct nuclei were replaced by irregularly distributed chromosome masses, and normal nuclear division was not observed. The CMI (chromosome mitosis index) values of wild-type strains rapidly increased within 60 min of treatment with carbendazim and then rapidly declined. Whereas the wild-type strains of the two fungi responded similarly, the carbendazim-resistant strains of F. graminearum and B. cinerea responded differently to carbendazim. The resistant strain of F. graminearum showed normal mitosis but produced significantly more branches and higher CMI values when treated with carbendazim than when untreated. In contrast, the carbendazim-resistant strain of B. cinerea exhibited normal morphology and mitosis after carbendazim treatment. The results suggest that the mechanism for carbendazim resistance in F. graminearum differs from that in B. cinerea and other fungi.

Laboratory toxicity test and post-exposure feeding inhibition using the giant freshwater prawn Macrobrachium rosenbergii

A bioassay was developed using post-larvae of freshwater prawn Macrobrachium rosenbergii (length 9–10 mm) in order to determine the toxicity of profenofos, dimethoate, chlorpyrifos, carbendazim and zinc. This was the first study in the tropics with M. rosenbergii, particularly at the post-larvae stage (9–10 mm) on lethal (LC 50) and sublethal (EC 50) effects of toxic substances using post-exposure feeding rate as end point. Median lethal concentrations (LC 50 at 24 and 48 h) were respectively estimated as 11.6 and 9.8 μg L −1 for profenofos, 142.1 and 102.7 μg L −1 for dimethoate, 0.7 and 0.3 μg L −1 for chlorpyrifos, and 439.7 and 329 μg L −1 for zinc. Effects of carbendazim could not be estimated because carbendazim exposure needs more than 24 h exposure period to produce observable effects at the concentrations used. The EC 50 using post-exposure feeding rates determined for profenofos, dimethoate, chlorpyrifos and zinc were 6.023, 269.3, 0.293 and 109.01 μg L −1, respectively, at 24 h of exposure. Only chlorpyrifos and zinc had LC 50 concentrations greater than the post-exposure feeding EC 50 concentrations. This study demonstrated that the M. rosenbergii could also be used as a test animal to detect the effects of different chemical contaminants in aquatic environments.

The use of the multivariate Principal Response Curve (PRC) for community level analysis: a case study on the effects of carbendazim on enchytraeids in Terrestrial Model Ecosystems (TME)

The effects of the fungicide carbendazim (formulation Derosal) on enchytraeids were determined in Terrestrial Model Ecosystem (TME) tests. TMEs consisted of intact soil columns (diameter 17.5 cm; length 40 cm) taken from three grassland sites (Amsterdam (The Netherlands), Bangor (Wales, England) and Flörsheim (Germany)) or an arable site (Coimbra (Portugal)). Results for each TME site were evaluated using the multivariate Principal Response Curve (PRC) method. The resulting No-Observable Effect Concentrations (NOECs) for the community were compared with the NOECs generated by univariate statistical methods. Furthermore, the EC(50)s (median effect concentrations) for the three taxa with the highest taxon weights determined by the PRC were compared with EC(50)s for the other endpoints. In eight out of 16 cases the PRC revealed the lowest NOEC for the enchytraeid species community. The lowest EC(50)s with the closest 95% confidence limits were calculated for the abundance of the three taxa with the highest taxon weights identified by the PRC. The EC(50)s ranging from 0.19-2.79 mg carbendazim/kg soil are similar to values from laboratory toxicity studies reported in the literature. Therefore, PRC is a useful instrument to analyse microcosm and mesocosm experiments; it allows for determination of NOECs for the species community (NOEC(community)), the evaluation of the taxa with the most pronounced treatment-related decrease in abundance and of the calculation of meaningful EC(50) values for those. The resulting NOEC(community) and EC(50) values offer a comprehensive tool for the risk assessment of chemicals at the ecosystem level.

Effect of carbendazim and physicochemical factors on the growth and ochratoxin A production of Aspergillus carbonarius isolated from grapes

Carbendazim is a systemic fungicide that is commonly used on several crops (tobacco, fruit, vegetables, cereals, etc.). This fungicide is used to control fungal infections in vineyards. It is indicated against Botrytis cinerea, Uncinula necator, Plasmopara viticola and other fungi and can be used either alone or coupled with other fungicides. However, there is a lack of in-depth studies to evaluate its effectiveness against growth of Aspergillus carbonarius isolated from grapes and OTA production. A medium based on red grape juice was used in this study. Preliminary studies were performed at 0.98 a w and 25 °C using carbendazim concentrations over a wide range (1–2000 ng/ml medium) to control both growth of a strain of A. carbonarius isolated from grape and its ability to produce OTA. As the lag phase increased considerably at levels > 1000 ng/ml of medium, detailed studies were carried out in the range 50–450 ng/ml of medium at 0.98–0.94 a w and 20–28 °C. Statistical analysis (multifactor ANOVA) of the data revealed that the three factors assayed and the interactions a w–carbendazim concentration and a w–temperature had significant effects on lag phase duration. The highest lag-times were observed at 0.94 a w, 20 °C, and with 450 ng carbendazim/ml. The three factors also had significant effects of the growth rate and there was an interaction between a w and temperature. The growth rate of A. carbonarius in these cultures is favoured by high water availability and relatively high temperatures. However, addition of carbendazim at the assayed levels did not significantly influenced fungal growth rate. Accumulation of OTA was studied as a function of four factors (the three previously considered, and time). All factors had significant effects on the accumulation of OTA. There were also two significant interactions ( a w–temperature and temperature–time). On the basis of the results obtained, carbendazim does not increase the lag phase of A. carbonarius except at relatively low a w and temperatures. It does not substantially decrease fungal growth rate once growth is apparent but it appears to cause an increase in OTA accumulation in the medium at the doses assayed. Carbendazim, which is widely used against fungal infections in grape, can positively influence OTA production by A. carbonarius in field, which can increase OTA content in grape juices and wines.

Effect of carbendazim and mancozeb combinationon Alternaria leaf blight and seed yield in sunflower (Helianthus annus L.)

Leaf blight caused by Alternaria helianthi (Hansf.) Tubaki & Nishihara, is the major disease of sunflower affecting the successful cultivation across India. Five individual fungicides and two combination fungicides were evaluated against this pathogen in laboratory and in field experiments. Among them, the combination of carbendazim + mancozeb completely (100%) inhibited the mycelial growth of A. helianthi, irrespective of the concentrations tested followed by carbendazim alone and metalaxyl + mancozeb under in vitro condition. In field conditions, the combination of carbendazim + mancozeb was found to be highly effective in reducing the leaf blight disease of sunflower in all the three experiments as compared to other fungicides and unsprayed control. The reduction of Alternaria leaf blight was also directly associated with an increase in seed yield. The economics of the fungicides spray has been worked out and the benefit cost ratio for the combination of carbendazim + mancozeb at 2.0 g/l was 7.1 as compared to unsprayed control. The overall analysis of the results revealed that the combination of carbendazim + mancozeb at 2.0 g/l can be used for the management of foliar diseases such as Alternaria leaf spot/blight in agricultural crops.

Determination of carbendazim residues in the eggs, liver and pectoral muscle of Japanese quail (Coturnix coturnix japonica)

The effect of carbendazim, a widely applied cereal seed dressing agent, was studied in Japanese quail (Coturnix coturnix japonica) during an overall period of eight weeks, consisting of a four-week feeding phase and a subsequent four-week excretion period. Body mass and feed consumption of the birds were monitored and residues of the active ingredient were determined by an analytical chemical method. During the eight-week study period, changes (either decrease or increase) directly attributable to the toxic effects of carbendazim were not found either in body mass or in feed consumption. Active ingredient levels exceeding the limit of detection were found in the liver (average: 0.0262 mg/kg) and pectoral muscle (average: 0.0236 mg/kg) of the birds and also in the egg (0.0338 mg/kg) samples. From the results it can be concluded that through the consumption of cereal seeds dressed with carbendazim, this active ingredient can be incorporated into the tissues of animals. Via the food chain, carbendazim can also enter the human organism, where it may cause various pathological changes in interaction with other chemicals.

Dose-dependent effects of carbendazim on rat thymus

In this study, the effects of carbendazim on the thymus in male rats were evaluated. Carbendazim was administered at 0, 150, 300 and 600 mg kg(-1) day(-1) doses by gavage to male rats for 15 weeks. Body weights of rats in all groups were recorded weekly during treatment. At the end of the experiment, the effects of carbendazim on the thymus were investigated histopathologically and morphologically. Also, based on these effects, change in immunolocalization of fibronectin (FN), which is a component of the extracellular matrix, was investigated immunohistochemically. Fibrosis and oedema were observed in the thymus of rats treated with 300 and 600 mg kg(-1) day(-1) doses of carbendazim. Also in this region, an increase in FN density was noted at the end of the immunohistochemical investigation. A decrease was observed in absolute and relative thymus weights of rats treated with carbendazim compared with the control group. While the decrease in absolute thymus weight was statistically significant in rats exposed to carbendazim at the highest dose, the decrease in relative thymus weights was statistically significant for all carbendazim doses.

Ring-testing and field-validation of a terrestrial model ecosystem (TME)--an instrument for testing potentially harmful substances: effects of carbendazim on enchytraeids.

The effects of the fungicide carbendazim (applied in the formulation Derosal) on enchytraeids were determined in Terrestrial Model Ecosystem (TME) tests and field-validation studies. TMEs consisted of intact soil columns (diameter 17.5 cm; length 40 cm) taken from a grassland or, in one case, from an arable site. The TMEs were taken from the same site where the respective field study was performed. The tests were performed in Amsterdam (The Netherlands), Bangor (Wales, England), Coimbra (Portugal) and Flörsheim (Germany). Concerning the enchytraeid overall abundance and the number of species, differences between sampling points and differences between the TME tests and the respective field-validation studies were not found in the controls. Generally, a high variability of data which reduced the probability of determining statistically significant differences was determined. Effects of the model chemical carbendazim were determined for the overall abundance of enchytraeids and the number of enchytraeid species. The clearest dose-response relationship was found for the abundance of the genus Fridericia. The abundance of the genera Achaeta and Enchytraeus was not affected. Effects were most pronounced 8 and 16 weeks after application of the test chemical. The observed effects appeared not to differ between the TME tests and the respective field-validation studies. Due to the high variability of data NOEC-values could often not be determined. The EC50-values derived from the TME pre-test, TME ring-test and field-validation study indicate that the reproducibility (i.e. the variation between the partners) of the EC50-values was reasonable, although different soils were used at the different sites. The EC50-values for effects of carbendazim on enchytraeid abundance ranged between 0.5 and 28.4 kg a.i./ha (corresponding to 0.7-37.8 mg/kg), on the number of species between 7.2 and 87.4 kg a.i./ha (9.5-116.2 mg/kg) and on the abundance of Fridericia between 0.7 and 18.6 kg a.i./ha (0.9-24.7 mg/kg). Since one specific taxon has the potential to be more sensitive for a chemical stressor than other taxa, it is recommended to include investigations on the species level in the assessment of TME or field studies.

Ring-testing and field-validation of a terrestrial model ecosystem (TME)--an instrument for testing potentially harmful substances: effects of carbendazim on soil microbial parameters.

The effects of carbendazim on substrate induced respiration (SIR), dehydrogenase activity (DHA), phosphatase activity and thymidine incorporation by bacteria were evaluated in an experiment with an open intact Terrestrial Model Ecosystem (TME) and in a simultaneous field-validation study. Experiments were performed on four different European soils in Germany, The Netherlands, United Kingdom and Portugal. Data analysis focused on (i) detecting differences between experiments, especially in control values, (ii) checking similarity in data variability at each treatment level between experiments and (iii) analysing the resemblance of response to the model chemical in both experiments. Results obtained showed that control values from TME experiments were similar to those obtained on the respective field site, in most of the comparisons made for SIR, DHA and thymidine incorporation. Phosphatase activity revealed more differences, but values of both experiments had the same order of magnitude. At least part of the variation could be explained from the correlation of the microbial parameters with soil moisture content. Comparisons on data variability also revealed the absence of significant differences between experiments in all parameters in most cases, indicating that TMEs were able to represent the spatial variability found in the field. Effects of carbendazim, when occurring, were observed at treatment levels exceeding the highest recommended application rate of 0.36 kg a.i./ha. Effects on SIR and DHA were observed early in time, but effects on phosphatase activity and thymidine incorporation rate were found 8 or 16 weeks after chemical application. These effects were mild, and rarely a 50% inhibition on any of these parameters was seen at carbendazim dosages up to 87.5 kg a.i./ha. The response to the model chemical in TMEs and field plots was similar in most cases. These results give promising prospects for the use of TMEs as an integrative tool in higher tier levels of different assessment schemes.

A Novel Assay System of Chemicals Using In-vitro Maturation of Mouse Oocytes: Effects of Carbendazim and Griseofulvin

In order to develop an in-vitro assay system for detection of cytogenetic toxicity of chemicals, we cultured mouse oocytes in vitro with two kinds of spindle poisons, carbendazim (MBC) and griseofulvin (GF). When cultured for 15 h with MBC (6 μg/ml), the majority of the oocytes arrested maturation at the metaphase in the first meiosis. This effect of MBC could be achieved with the latter half of the exposure during 15 h for the entire culture. In contrast, a significant proportion of the oocytes cultured with GF (10 μg/ml) could not continue meiosis from the germinal vesicle stage. Therefore, we characterized the difference in the effects of MBC and GF on meiotic progression of mouse oocytes by using this in-vitro assay system, demonstrating that the system would be useful for detection of cytogenetic toxicity of chemicals.

Fungicidal Impact on Chickpea–Mesorhizobium Symbiosis

The effects of carbendazim, captan, thiram, and mancozeb, on plant vitality, chlorophyll content, N uptake, protein content, nodulation, and seed yield in chickpea (Cicer arietinum) were assessed in a controlled environment. Seeds treated with fungicides at 1 and 1.5 g. a.i./kg seed had no significant adverse effect on plant vigor, seed yield, and N and protein contents. In contrast, fungicides applied at 2 g. a.i./kg of captan, thiram and mancozeb, significantly reduced the measured parameters. In general, the toxicity of fungicides in terms of seed yield increased in the following order: Control = carbendazim > thiram > captan > mancozeb. Total chlorophyll content in foliage declined consistently with fungicides dose rates and application days. Seeds treated with lower rates of fungicides significantly increased nodulation (nodule number per plant and its dry mass) and were compatible with chickpea inoculum used in this study. Although carbendazim at 2 g a.i./kg seed had no phytotoxic effect assessed under greenhouse conditions, it significantly reduced the chlorophyll content, nodulation (60 d) and N content in shoots.

Effects of carbendazim on rat thyroid, parathyroid, pituitary and adrenal glands and their hormones.

The purpose of this study is to determine the effects of low and high dose of carbendazim on the level of certain hormones and endocrine glands (thyroid, parathyroid, adrenal and pituitary glands) of male rats. Carbendazim is a systemic fungicide with activity against a number of plant pathogens. In this study, daily doses of 0, 150, 300 and 600 mg/kg per day carbendazim were applied to male rats by gavage for 15 weeks. At the end of the experiment, T3, T4, TSH, ACTH and GH levels in rat serum were analysed. Thyroid, parathyroid, adrenal and pituitary glands of rats were taken. A significant increase was observed in serum T3 levels of the rats, which were exposed to 300 mg/kg per day carbendazim doses, compared to the serum T3 levels of the control group. There were no differences between the control and carbendazim-treated group of rats regarding serum TSH, T4, ACTH and growth hormone levels. This showed us that carbendazim caused histopathological damages in thyroid, parathyroid and adrenal glands of rats. No changes were observed in pituitary glands of treated rats. These results suggest that a high quantity of subchronic carbendazim exposure affects thyroid, parathyroid and adrenal glands.

Effects of three chemicals on the survival and reproduction of the oligochaete worm Enchytraeus coronatus in chronic toxicity tests

Using Enchytraeus coronatus as a test organism, we have measured the effects of Derosal (carbendazim as active ingredient), 4-nitrophenol and potassium dichromate on survival (Lethal Concentration: LC50) and on several sublethal variables (Effective Concentrations: EC10, EC50 and the No Observed Effective Concentration: NOEC), in chronic agar tests. Worms were also exposed to carbendazim and potassium dichromate in a soil toxicity test (Enchytraeid Reproduction Test, ERT). Sublethal variables measured in agar tests (number of juveniles and cocoons per adult, number of eggs per cocoon, percent of hatching and adult biomass) were used to facilitate interpretation of the causes of reproductive inhibition of the number of juveniles in the ERT soil toxicity test. Effective concentrations (EC) were estimated using Probit and logistic models. The later provided a better fit for the response of the worms exposed to carbendazim in agar test, in which an increase of the number of juveniles with respect to control was found at low doses. The number of juveniles per adult was the most sensitive variable measured for the three substances in the agar toxicity tests. The reduction in the number of juveniles could be explained mainly by a negative effect on cocoon hatching due to carbendazim (4-week NOEC juveniles/adult = 0.32 mg l—1, 4-week EC10 Reproductive inhibition (RI) = 0.37mg l—1), a result probably related to failure of embryonic development. The effect of 4-nitrophenol on the number of juveniles (4-week NOEC = 0.32mg l—1, 4-week EC10 (RI) = 0.25 mg l—1) was interpreted as a consequence of a reduction in the number of eggs per cocoon, associated with a reduction in parental biomass. Reproductive inhibition (RI) in worms exposed to potassium dichromate (4-week NOEC juveniles/adult = 0.32mg l—1, 4-week EC10 (RI) = 0.40 mg l—1) was explained by a reduction in cocoon production, which apparently was not related to the loss of parental biomass but rather to a failure of worm reproductive physiology. The results of this study provide useful information regarding the effects of carbendazim, 4-nitrophenol and potassium dichromate on worm reproduction biology and contribute to our understanding of the effects of these substances measured in ERT soil toxicity tests.

Antifungal effect of carbendazim supported on poly(ethylene‐co‐vinyl alcohol) and epoxy resin

Antifungal effect of carbendazim supported on poly(ethylene‐co‐vinyl alcohol) and epoxy resin

Effects of carbendazim (methyl 2‐benzimidazole carbamate; MBC) on meiotic spermatocytes and subsequent spermiogenesis in the rat testis

Effects of carbendazim (methyl 2‐benzimidazole carbamate; MBC) on meiotic spermatocytes and subsequent spermiogenesis in the rat testis

Effects of carbendazim (methyl 2-benzimidazole carbamate; MBC) on meiotic spermatocytes and subsequent spermiogenesis in the rat testis

Benzimidazole fungicide, carbendazim, is known to adversely affect Sertoli cells by disrupting microtubules, which induces sloughing of elongate spermatids in a stage-specific manner. This study determines the direct effects on dividing germ cells and the subsequent effects on spermiogenesis. Carbendazim was administered orally to male rats (100 mg/kg), and their testes were processed for histological evaluation at various post-treatment intervals up to day 20.0. The sloughing of elongate spermatids was observed as reported previously. In addition to this Sertoli cell lesion, necrosis of dividing spermatocytes in stage XIV was observed at 8 hours post-treatment. At day 1.5, empty spaces of missing step 1 spermatids were seen in stage I. At days 4.5 and 7.5, normal round spermatids were missing, but large round spermatids (megaspermatids) and binucleate spermatids were common. The megaspermatid nucleus was approximately 33% larger in diameter than normal round spermatids. At day 10.5, megasteps 10-12 spermatids, binucleate spermatids, and three to four different steps of spermatids coexisting in the same tubule section were present in stages X-XII. In addition, abnormally shaped elongating spermatids were observed having distorted heads and nuclear invagination containing microtubules. At day 20.0, empty spaces of missing diplotene spermatocytes were seen in stage XIII. The present observations show that carbendazim has rapid direct effects on meiotic spermatocytes and latent effects on spermatids, leading to morphological abnormalities and failure of spermiogenesis. These effects are found independent of occlusions in the efferent ductules.

The effect of fungicides on sugar beet infected with beet mild yellowing virus

Studies were made in 1989, 1990 and 1991 to establish whether carbendazim (MBC) had a direct therapeutic effect on sugar beet plants infected with beet mild yellowing virus (BMW), resulting in detectable yield benefits. In a field trial in 1989 virus-infected plots treated with carbendazim gave a significantly higher yield, of 0.66 t sugar/ha, than virus-infected plots sprayed with sulphur to control powdery mildew. This response to carbendazim in virus-inoculated plots was not repeated in subsequent trials in 1990 and 1991, and a glasshouse study showed no apparent effect on virus concentration within inoculated plants. Neither was any effect of carbendazim on symptom development observed in any of the trials or glasshouse experiments.

Acute and long-term effects of a single dose of the fungicide carbendazim (methyl 2-benzimidazole carbamate) on the male reproductive system in the rat.

The effects of carbendazim (methyl 2-benzimidazole carbamate) on the testis, efferent ductules, and sperm were determined in the adult rat after a single oral dose. Two experimental trials were performed: a time response between 2 hours and 32 days after exposure using 0 and 400 mg/kg, and a dose response at 2 and 70 days after exposure using 0 to 800 mg/kg doses. In experiment 1, effects were seen throughout the 32-day period, beginning 8 hours after exposure; the effects included first an increase in testis weight, then decreases in testicular spermatid numbers and in the percentage of morphologically normal cauda sperm. In experiment 2, significant testicular and efferent ductal alterations occurred in animals treated with doses of 100 mg/kg or greater. A dose-dependent increase in testicular weight 2 days after treatment was accompanied by increases in seminiferous tubular diameter and excessive loss of immature germ cells in a stage-dependent manner. There was also a dose-dependent increased incidence of occlusions in the efferent ductules. The occluded ductules were characterized by severe inflammation and exhibited disorganization of the epithelium. At 70 days, there were dose-dependent decreases in mean testis weight and mean seminiferous tubular diameter; however, only minimal long-term effects were seen at 50 mg/kg. In testes exhibiting seminiferous tubular atrophy of greater than 25% (100 mg/kg or greater doses), all of the testes were associated with efferent ductules containing occlusions. Caput sperm numbers were significantly reduced in these testes. Occlusions, abnormal ductules, fibrosis, spermatic granulomas, and mineralization were observed in the ductuli efferents. Long-term effects of carbendazim on the testis were induced primarily by ductal occlusions. Results show that carbendazim produces more severe short- and long-term effects on the male reproductive system than the fungicide benomyl.

Carbendazim resistance in the eyespot pathogen Pseudocercosporella herpotrichoides

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.