Related Fungicides Research Articles

Development and Validation of a Novel Method Using QuEChERS and UHPLC-MS-MS for the Determination of Multiple Emerging Fungicides in Surface Waters

The increasing global reliance on pesticides for agricultural pest control has raised significant environmental concerns, particularly due to inadequate monitoring of emerging chemicals in surface waters. This study addresses the potential contamination of aquatic ecosystems by developing and validating a method for detecting trace amounts of four recently registered fungicides: three succinate dehydrogenase inhibitors (fluopyram, penthiopyrad, pydiflumetofen) and fluopicolide, a structurally related fungicide. Employing QuEChERS-based sample extraction combined with ultra-high-performance liquid chromatography (UHPLC-MS-MS), this method achieves detection limits of 0.1 to 0.2 μg/L, with recovery rates between 90% and 110%, and intra-day relative standard deviation values well within the acceptable range of less than 20%. Applied to surface grab water samples from the greater Melbourne area, Australia, the method successfully identified all four fungicides at trace levels, including a notable high concentration of fluopyram (7.3 μg/L) during autumn, with the others intermittently detected at lower concentrations. This study represents the first documented instance of quantifiable detections of these four fungicides in Australian surface water systems. Given their high toxicity to several organisms and the limited global data on these substances, our findings underscore the critical need for continuous monitoring to inform strategies to safeguard aquatic ecosystems from these chemicals.

Fungicides alter the distribution and diversity of bacterial and fungal communities in ginseng fields

ABSTRACT The present study was focused on comparison of four typical fungicides in ginseng field to evaluate the impact of the different fungicides on the soil bacterial and fungal communities’ composition and diversity by using high-throughput sequencing. Five treatments were designed comprising carbendazim (D), dimethyl disulfide (E), dazomet (M), calcium cyanamide (S), and control (C). The application of fungicide obviously altered the distribution of dominant fungal and bacterial communities and remarkably decreased the diversity (1099-763 and 6457-2245). The most abundant Proteobacteria obviously degenerate in fungicide-treated soil and minimum in E (0.09%) compared to control (25.72%). The relative abundance of Acidobacteria was reduced from 27.76 (C) to 7.14% after applying fungicide and minimum in E. The phylum Actinobacteria are both decomposers of organic matter and enemies of soil-borne pathogens, elevated from 11.62 to 51.54% and are high in E. The fungi community mainly distributed into Ascomycota that enriched from 66.09 to 88.21% and highin M and E (88.21 and 85.10%), and Basidiomycota reduced from 21.13 to 3.23% and low in M and E (5.27 and 3.23%). Overall, environmentally related fungicides decreased the diversity and altered the composition of bacterial and fungal communities, highest sensitivity present in dimethyl disulfide-treated soil.

Preparation of coal-derived magnetic carbon material for magnetic solid-phase extraction of fungicides from water samples

A magnetic solid-phase extraction method has been developed for the extraction and analysis of some fungicides in environmental water samples. Azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin were the target fungicides selected. First, a carbon material was obtained from the raw coal sample collected from Zonguldak region by ash removal process and then a magnetic C/Fe3O4 composite was produced from the carbon material using a single-step thermal method. The magnetic C/Fe3O4 composite was characterized by N2 adsorption-desorption, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. This composite was then used as an adsorbent for the magnetic solid-phase extraction of fungicides from water samples followed by high-performance liquid chromatographic analysis. Experimental parameters affecting the extraction efficiency such as adsorbent amount, type and volume of desorption solvent, adsorption and desorption time, ionic strength, and pH were optimized. Under the optimized conditions, the extraction efficiency for azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin was found to be 71%, 44%, 41% and 70%, respectively. The method detection limits for fungicides were found to be in the range of 0.4-1.1 µg L-1. The relative standard deviations were found to be lower than 6.6% and 6.9% for intra-day and inter-day precisions, respectively. The extraction of related fungicides from water samples collected from Zonguldak region was carried out efficiently. The recoveries obtained from spiked water samples were in the range of 71–106%.

Characterization of two novel mycoviruses from Penicillium digitatum and the related fungicide resistance analysis

Pathogenic fungi including Penicillium digitatum and Penicillium italicum are the main destructive pathogens in the citrus industry, causing great losses during postharvest process. To our knowledge, only one mycovirus from P. digitatum has been reported, and the prevalence of such mycoviruses against citrus postharvest pathogenic fungi and their genotyping were still under investigation. In the present study, we showed that 39 of 152 Penicillium isolates from main citrus-growing areas in China were infected with various mycoviruses belonging to polymycoviruses, Narna-like viruses, and families Totiviridae, Partitivirdae and Chrysoviridae. The next generation sequencing (NGS) towards virus genome library and the following molecular analysis revealed two novel mycoviruses Penicillium digitatum polymycovirus 1 (PdPmV1) and Penicillium digitatum Narna-like virus 1 (PdNLV1), coexisting in P. digitatum strain HS-RH2. The fungicide-resistant P. digitatum strains HS-F6 and HS-E9 coinfected by PdPmV1 and PdNLV1 exhibited obvious reduction in triazole drug prochloraz resistance by mycelial growth analysis on both PDA plates and citrus fruit epidermis with given prochloraz concentration. This report at the first time characterized two novel mycoviruses from P. digitatum and revealed the mycovirus-induced reduction of fungicide resistance.

Synthesis of N-substituted phthalimides and their antifungal activity against Alternaria solani and Botrytis cinerea

As organosulfur and organophosphorus agents, phaltane and phosmet are facing great challenges for the environmental contamination, mammalian toxicity and increasing resistance with long term use. It is efficient and meaningful to develop phthalimide-based alternatives with non-sulfur and non-phosphorus groups. A series of N-substituted phthalimides were synthesized and their antifungal activity against two disastrous phytopathogenic fungi, Alternaria solani and Botrytis cinerea was evaluated in vitro. Most of them showed significant antifungal activity against both of fungi, or either of them selectively. N-vinylphthalimide (4) and 8-[4-(phthalimide-2-yl) butyloxy] quinoline (13) were identified as the most promising candidates against B. cinerea and A. solani with the IC50 values of 7.92 μg/mL and 10.85 μg/mL respectively. The brief structure-activity relationships have revealed that vinyl, quinolyl, bromide alkyl and benzyl substitutions were appropriate substituents and coupling functional moieties indirectly with optimum alkyl chain was efficient to prepare phthalimides related fungicides.

The nematode Caenorhabditis elegans as a tool to predict chemical activity on mammalian development and identify mechanisms influencing toxicological outcome.

To determine whether a C. elegans bioassay could predict mammalian developmental activity, we selected diverse compounds known and known not to elicit such activity and measured their effect on C. elegans egg viability. 89% of compounds that reduced C. elegans egg viability also had mammalian developmental activity. Conversely only 25% of compounds found not to reduce egg viability in C. elegans were also inactive in mammals. We conclude that the C. elegans egg viability assay is an accurate positive predictor, but an inaccurate negative predictor, of mammalian developmental activity. We then evaluated C. elegans as a tool to identify mechanisms affecting toxicological outcomes among related compounds. The difference in developmental activity of structurally related fungicides in C. elegans correlated with their rate of metabolism. Knockdown of the cytochrome P450s cyp-35A3 and cyp-35A4 increased the toxicity to C. elegans of the least developmentally active compounds to the level of the most developmentally active. This indicated that these P450s were involved in the greater rate of metabolism of the less toxic of these compounds. We conclude that C. elegans based approaches can predict mammalian developmental activity and can yield plausible hypotheses for factors affecting the biological potency of compounds in mammals.

Baseline Sensitivity and Cross-Resistance to Succinate-Dehydrogenase-Inhibiting and Demethylation-Inhibiting Fungicides in Didymella bryoniae.

Didymella bryoniae, which causes gummy stem blight (GSB) of watermelon, has a history of developing resistance to fungicides, most recently the succinate-dehydrogenase-inhibiting (SDHI) fungicide boscalid. To facilitate fungicide resistance monitoring, baseline sensitivity distributions were established for demethylation-inhibiting (DMI) fungicides tebuconazole and difenoconazole and the SDHI fungicide penthiopyrad, and reestablished for the SDHI fungicide boscalid. In all, 71 isolates with no known prior exposure to SDHIs or DMIs were used to determine the effective concentration at which mycelial growth was inhibited by 50% (EC50). EC50 values for boscalid, penthiopyrad, tebuconazole, and difenoconazole were 0.018 to 0.064, 0.015 to 0.057, 0.062 to 0.385, and 0.018 to 0.048 μg/ml, with median values of 0.032, 0.026, 0.118, and 0.031 μg/ml, respectively. Significant positive correlations between the sensitivity to penthiopyrad and boscalid (P < 0.0001, r = 0.75) and between tebuconazole and difenoconazole (P < 0.0001, r = 0.59) indicate a potential for cross-resistance between chemically related fungicides. In 2009, 103 isolates from fungicidetreated watermelon fields were tested for sensitivity to boscalid and penthiopyrad using a discriminatory concentration of 3.0 μg/ml. Of the isolates tested, 82 were insensitive and 14 were sensitive to both fungicides. Because of the significant potential for cross-resistance between closely related fungicides, growers will be advised not to use both SDHIs or both DMIs successively in the same fungicide spray program.

Five Carboxin-Resistant Mutants Exhibited Various Responses to Carboxin and Related Fungicides

Five carboxin-resistant mutants from Aspergillus oryzae were characterized by the sensitivities of their mycelial growth and succinate dehydrogenase (SDH) activity to carboxin and three related fungicides. Despite a significant resistance to carboxin, exhibited by all the mutants, their patterns of sensitivity to the other fungicides was distinct. This provides clues to the molecular interaction between SDH and these fungicides.

Air Pollutants Formed in Thermal Decomposition of Folpet Fungicide under Oxidative Conditions

This contribution studies the decomposition of folpet fungicide under oxidative conditions and compares the product species with those of captan fungicide, which is structurally related to folpet. Toxic products arising from folpet comprised carbon disulfide (highest emission factor of 4.9 mg g(-1) folpet), thiophosgene (14.4), phosgene (34.1), hydrogen cyanide (2.6), tetrachloroethylene (111), hexachloroethane (167), and benzonitrile (4.5). Owing to their related molecular structures, folpet emitted similar products to captan but at different yields, under the same experimental conditions. It appears that the availability of easily abstractable H atoms, in the structure of captan but not in that of folpet, defines the product distribution. In conjunction with the quantum chemical calculations, these experimental measurements afford an enhanced explanation of the formation pathways of hazardous decomposition products of these two structurally related fungicides.

Effect of the F129L Mutation in Alternaria solani on Fungicides Affecting Mitochondrial Respiration.

Isolates of Alternaria solani previously collected from throughout the Midwestern United States and characterized as being azoxystrobin sensitive or reduced sensitive were tested for sensitivity to the Quinone outside inhibitor (QoI) fungicides famoxadone and fenamidone and the carboxamide fungicide boscalid. All three fungicides affect mitochondrial respiration: famoxadone and fenamidone at complex III, and boscalid at complex II. A. solani isolates possessing reducedsensitivity to azoxystrobin also were less sensitive in vitro to famoxadone and fenamidone compared with azoxystrobin-sensitive isolates, but the shift in sensitivity was of lower magnitude, approximately 2- to 3-fold versus approximately 12-fold for azoxystrobin. The in vitro EC50 values, the concentration that effectively reduces germination by 50% relative to the untreated control, for sensitive A. solani isolates were significantly lower for famoxadone and azoxystrobin than for fenamidone and boscalid; whereas, for reduced-sensitive isolates, famoxadone EC50 values were significantly lower than all other fungicides. Isolates of A. solani with reducedsensitivity to azoxystrobin were twofold more sensitive in vitro to boscalid than were azoxystrobin-sensitive wild-type isolates, displaying negative cross-sensitivity. All isolates determined to have reduced-sensitivity to azoxystrobin also were determined to possess the amino acid substitution of phenylalanine with leucine at position 129 (F129L mutation) using real-time polymerase chain reaction. In vivo studies were performed to determine the effects of in vitro sensitivity shifts on early blight disease control provided by each fungicide over a range of concentrations. Reduced-sensitivity to azoxystrobin did not significantly affect disease control provided by famoxadone, regardless of the wide range of in vitro famoxadone EC50 values. Efficacy of fenamidone was affected by some azoxystrobin reduced-sensitive A. solani isolates, but not others. Boscalid controlled azoxystrobin-sensitive and reduced-sensitive isolates with equal effectiveness. These results suggest that the F129L mutation present in A. solani does not convey cross-sensitivity in vivo among all QoI or related fungicides, and that two- to threefold shifts in in vitro sensitivity among A. solani isolates does not appreciably affect disease control.

A critical evaluation of the role of alternative oxidase in the performance of strobilurin and related fungicides acting at the Qo site of complex III.

Mitochondrial respiration conserves energy by linking NADH oxidation and electron-coupled proton translocation with ATP synthesis, through a core pathway involving three large protein complexes. Strobilurin fungicides block electron flow through one of these complexes (III), and disrupt energy supply. Despite an essential need for ATP throughout fungal disease development, strobilurins are largely preventative; indeed some diseases are not controlled at all, and several pathogens have quickly developed resistance. Target-site variation is not the only cause of these performance difficulties. Alternative oxidase (AOX) is a strobilurin-insensitive terminal oxidase that allows electrons from ubiquinol to bypass Complex III. Its synthesis is constitutive in some fungi but in many others is induced by inhibition of the main pathway. AOX provides a strobilurin-insensitive pathway for oxidation of NADH. Protons are pumped as electrons flow through Complex I, but energy conservation is less efficient than for the full respiratory chain. Salicylhydroxamic acid (SHAM) is a characteristic inhibitor of AOX, and several studies have explored the potentiation of strobilurin activity by SHAM. We present a kinetic-based model which relates changes in the extent of potentiation during different phases of disease development to a changing importance of energy efficiency. The model provides a framework for understanding the varying efficacy of strobilurin fungicides. In many cases, AOX can limit strobilurin effectiveness once an infection is established, but is unable to interfere significantly with strobilurin action during germination. A less stringent demand for energy efficiency during early disease development could lead to insensitivity towards this class of fungicides. This is discussed in relation to Botrytis cinerea, which is often poorly controlled by strobilurins. Mutations with a similar effect may explain evidence implicating AOX in resistance development in normally well-controlled plant pathogens, such as Venturia inaequalis.

Toxicity of the dithiocarbamate fungicide mancozeb to the nontarget soil nematode, Caenorhabditis elegans.

We have previously shown that the dithiocarbamate fungicide, Mancozeb, strongly induces lacZ reporter expression from an endogenous heat-shock promoter (hsp16) in the PC72 transgenic strain of the nematode Caenorhabditis elegans. Such evidence of organismal stress, in a nontarget species at subapplication concentrations, was much less apparent for the related fungicide, Maneb, which only weakly induced reporter expression. We now show that reporter induction by Mancozeb is marginal (<60%) after a few hours' exposure, but increases substantially (to almost 10-fold) after overnight exposure. In conjunction with our previous results using intermediate exposure periods, this suggests that the factor limiting reporter responses is likely to be a slow rate of uptake and/or metabolism of the fungicide. We confirm that a potentially toxic metabolite of dithiocarbamate fungicides, namely ethylenethiourea (ETU), has minimal toxicity toward C. elegans, even after prolonged exposure at high concentrations. We demonstrate that exposure to Mancozeb (but not ETU) significantly inhibits larval growth in C. elegans, although this parameter is not markedly more sensitive than reporter induction as a toxicological endpoint. Finally, we have used two-dimensional electrophoresis to show that high concentrations of both Maneb and Mancozeb drastically simplify the protein spot profile compared with controls. However, only in the latter case is there evidence of novel proteins being induced. Both fungicides appear toxic to C. elegans, but only Mancozeb induces a strong heat-shock response.

Determination of morpholine fungicides using the tris(2,2′-bipyridine) ruthenium(ii) chemiluminescence reaction

Chemiluminescence and electrogenerated chemiluminescence (ECL) methods based on the tris(2,2′-bipyridine) ruthenium(II) chemiluminescence reaction were compared for the analysis of morpholine fungicides. Both methods proved to be sensitive and selective for the determination of dodemorph. In the chemiluminescence system the tris(2,2′-bipyridine) ruthenium(II) was oxidised with Ce(IV) and the flow rate, coil length and pH were optimised by a multivariate method. In the ECL system, the tris(2,2′-bipyridine) ruthenium(II) was oxidised at an aluminium working electrode. The calibration characteristics of the two methods were similar. The linear range was between 2 × 10−7–1 × 10−5 mol l−1 for the chemiluminescence method and 1 × 10−7–3 × 10−5 mol l−1 for the ECL method. The limits of detection were 4.8 × 10−8 mol l−1 for chemiluminescence and 4.4 x10−8 mol l−1 for ECL. A related fungicide tridemorph was also determined by ECL and the linear range for that was between 5 × 10−7 and 5 × 10−5 mol l−1, with a limit of detection of 4.5 × 10−7 mol l−1. An interference study showed that the main interferences for both methods were ascorbic acid and oxalic acid that interfered at the 2 × 10−6 and 1.0 × 10−6 mol l−1 level, respectively. Good recoveries (96–100%) were obtained for the determination of dodemorph on cotton gloves and laboratory coats although a methanol extraction was used for the chemiluminescence method and a water extraction for the ECL method. This was because methanol depressed the ECL signal. A study of dodemorph uptake in barley was also carried out. Although ECL was the more elegant method for analysis it was less tolerant to methanol and this could be a disadvantage if it were required to extract the analyte from the sample.

Strategies to avoid resistance development to strobilurin and related fungicides in New Zealand

Strobilurins have a site-specific mode of action and there is potential for resistance to develop in target plant pathogenic fungi. STAR (strobilurin-type action and resistance) compounds form a crossresistance group that is different to other commercially available fungicides. The first strobilurin was registered for use in New Zealand in 1997 and resistance has not yet been reported in this country. Resistance has been reported overseas in wheat powdery mildew, grape downy mildew, banana black Sigatoka and cucurbit powdery mildew. Strategies developed under the auspices of the New Zealand Committee on Pesticide Resistance (NZCPR) to promote the use of STAR compounds in a way which avoids or delays the development of resistance in pathogens of apples, grapes, other fruit crops, vegetables and cereals in New Zealand are described.

Transgenic strains of the nematode C. elegans in biomonitoring and toxicology: Effects of captan and related compounds on the stress response

The fungicide, captan, induces a cellular stress response in the soil nematode Caenorhabditis elegans. Transgenic C. elegans, which produce β-galactosidase as a surrogate stress protein, reveal that captan-induced stress is localized mainly to muscle cells of the pharynx. The stress response is elicited by captan concentrations above 5 ppm and occurs within five hours of the initial exposure to the fungicide. Higher concentrations of captan, up to the solubility limit, increase the intensity of the response. Adult nematodes are significantly more sensitive to captan than are larvae. Captan also inhibits feeding in C. elegans, and nematodes exposed to captan rapidly cease muscular contractions in the pharynx. Stress induction and feeding inhibition are also caused by the related fungicides, captafol and folpet, but not by the parent compounds, phthalimide and tetrahydrophthalimide. The inhibition of feeding caused by compounds which elicit the cellular stress response may be an important survival mechanism for C. elegans.

ELISA for the detection of the triazole fungicide myclobutanil.

A competitive enzyme-linked immunosorbent assay (ELISA) system for quantitative detection of myclobutanil was developed. Polyclonal antibodies were raised in rabbits against the haptenic compound 2-(4-chlorophenyl)-2-[(1,2,4-triazol-1-yl)methyl]hexanoic acid, conjugated to conalbumin through the carboxylic acid moiety. The standard curve based on a homologous system using the above hapten conjugated to bovine serum albumin displayed a detection range from 0.3 to 200 μg/mL for myclobutanil with an IC 50 value of 4.9 ± 0.5 μg/mL. The effects of various assay conditions, including pH, organic solvent content, sample matrix effects (surface water, soil and fruit extracts), and protein stabilizer, on the sensitivity have been evaluated. Cross-reactivities with various related fungicides, insecticides, pharmaceuticals, and intermediates containing triazole, imidazole, or pyrimidine groups were tested and found to be below 15%. The detection system appears to be a versatile device for the environmental monitoring of myclobutanil.

Significance of Insensitivity ofSclerotinia minorto Iprodione in Control of Sclerotinia Blight of Peanut.

Four hundred isolates of Sclerotinia minor were obtained from diseased peanut plants (Arachis hypogaea) in field plots untreated or treated three times with iprodione (1.12 kg/ha) in 1987. On glucose-yeast extract agar containing iprodione at 2 μg/ml, only 6% of the isolates grew. These isolates produced more mycelial growth than corresponding isolates not previously exposed to the fungicide in agar, indicating that insensitivity developed in vitro. In field microplots artificially infested with sclerotia of the insensitive isolates and planted to peanut for 7 yr, iprodione provided significant disease suppression even though insensitive isolates could still be recovered. In a separate 3-yr microplot study, the pathogenicity of an isolate (B-83-T2) of S. minor suspected of possessing field resistance to dicarboximide fungicides was compared to a sensitive isolate (S-2) after treatment of peanuts with dicarboximide fungicides (iprodione or vinclozolin), aromatic hydrocarbon fungicides (dicloran or pentachloronitrobenzene [PCNB]), and an experimental fungicide (fluazinam). Without fungicide treatment, disease incidence (stem lesions per microplot) at harvest averaged 19.9 in plots infested with isolate S-2 and 18.3 in plots infested with isolate B-83-T2 (no statistical difference), but yields were significantly lower (10%) in microplots infested with isolate S-2. When averaged across isolates, disease incidence was suppressed 96, 63, 42, 41, and 2O% by fluazinam, vinclozolin, iprodione, PCNB, and dicloran, respectively. Insensitivity in S. minor to the dicarboximide fungicides appears low but persistent and does not pose a threat to the continued use of dicarboximides or related fungicides in peanut production

Similarities in the antifungal activities of fenpiclonil, iprodione and tolclofos‐methyl against Botrytis cinerea and Fusarium nivale

AbstractFenpiclonil [4‐(2,3‐dichlorophenyl)pyrrole‐3‐carbonitrile], a new agricultural fungicide, is a structural analogue of the antibiotic pyrrolnitrin used as an antimycotic in animals. Its spectrum of antifungal activity is similar to that of iprodione and tolclofos‐methyl, which are representatives of dicarboximide and aromatic hydrocarbon fungicides. Laboratory mutants of Botrytis cinerea and Fusarium nivale were simultaneously resistant to fenpiclonil, iprodione and tolclofos‐methyl and they showed an increased susceptibility to high osmotic pressure (sodium chloride, glucose). Strains of B. cinerea, collected in Champagne vineyards, which were resistant to dicarboximides were not resistant to fenpiclonil and tolclofos‐methyl. The antioxidant α‐tocopheryl acetate, and the cytochrome P‐450 inhibitors piperonyl butoxide and tebuconazole antagonized the fungitoxicity of fenpiclonil and iprodione in a wild‐type strain of B. cinerea. The uncoupling activity of fenpiclonil, iprodione and tolclofos‐methyl was detected in mitochondria from both a wild‐type strain and a laboratory mutant of B. cinerea. The concentrations effective towards this process were greater than those inhibiting the mycelial growth of wild‐type strains. These results suggest that fenpiclonil, iprodione, tolclofos‐methyl and related fungicides have the same biochemical mode of action. However, a primary effect on respiration, previously considered for pyrrolnitrin, seems to be improbable.

Comparative Studies of the Effects on Liver and Liver Microsomal Drug‐Metabolizing Enzyme System by the Fungicides Captan, Captafol and Folpet in Rats

Structurally related fungicides, captan, captafol and folpet are broad-spectrum, non-persistent fungicides widely used for the control of various fungus diseases of seeds, fruits and vegetable crops. The following studies were carried out in rats to compare the in vivo biochemical effects of these fungicides on liver and liver monooxygenases

Inhibitory action of benzimidazole fungicides on the in vivo incorporation of [ 3H]thymidine in various organs of the mouse

The effect of benomyl on the DNA turnover in various organs of the mouse was evaluated by measuring the incorporation of [ 3H]thymidine 24 hr after oral administration of different doses (1.3, 2.55 and 5.1 mmol/kg body weight) of benomyl. In the thymus, spleen and testis there was a clear relationship between dose and effect, the no-observed-effect level being 1.3 mmol/kg body weight. However, in the liver and kidney there was no obvious relationship between dose and effect, the [ 3H]thymidine incorporation being inhibited even at the lowest dose. Equimolar amounts of the closely related fungicide carbendazim inhibited the [ 3H]thymidine incorporation only in the testis. The observed difference between the two compounds was not a result of different absorption rates. Whole-body autoradiography indicated a rapid absorption and a similar distribution pattern for [phenyl(U)- 14C]benomyl and [phenyl(U)- 14C]carbendazim. Apart from an accumulation in the retina, liver and kidney, most other organs were almost devoid of [ 14C]benomyl- and [ 14C]carbendazim-associated radioactivity.