Inflammatory Myofibroblastic Tumor of the Sciatic Nerve Mimicking Lumbar Disc Herniation: A Diagnostic Challenge.

Inflammatory myofibroblastic tumors (IMTs), which involve the proliferation of fibroblastic-myofibroblastic cells mixed with inflammatory infiltrates, are exceedingly rare in the extremities. There are no reported IMTs involving the sciatic nerve. This type of involvement may cause entrapment of the sciatic nerve, whose symptoms may mimic lumbar disc herniation (LDH), especially when it occurs in patients with lumbar degenerative disc disease. We describe the case of a 40-year-old male with lumbar degenerative disc disease accompanied by IMT involving the sciatic nerve whose symptoms mimicked LDH and posed a diagnostic challenge. We showed the course of the disease as well as the systematic imaging manifestations of IMTs involving the sciatic nerve and discussed their therapeutic management.

Osteoblastic Bone Reaction Developing During Treatment With Sintilimab and Bevacizumab in a Patient With KRASG12V-Mutant Lung Adenocarcinoma.

Osteoblastic bone reaction, the occurrence of new osteoblastic lesions, is a paradoxical phenomenon during the treatment of cancers and can be defined as disease progression or bone metastases. Osteoblastic bone reactions usually occur in patients who receive treatments such as chemotherapy or hormonal or targeted therapy; however, it is difficult to differentiate them from disease progression or an increase in osteoblastic activity in response to therapy. Although osteoblastic bone reaction in lung cancer has been described in a few reports, it has never been reported in patients with KRASG12V-mutant lung adenocarcinoma treated with immunotherapy and antiangiogenesis. Here, we describe a case of a 77-year-old male with KRASG12V-mutant lung adenocarcinoma whose osteoblastic bone response was found during treatment with sintilimab and bevacizumab. We showed the course of the disease as well as systematic imaging manifestations of lung cancer with osteoblastic bone reaction and discussed their mechanisms.

Multiple Myeloma Rather Than Metastatic Lung Cancer: An Unexpected Cause of Spinal Cord Compression.

Spinal cord compression caused by cancer metastasis is a medical emergency that should be managed positively. Both multiple myeloma and lung cancer can lead to metastatic deposits in the spinal column to induce compression of the spinal cord. However, co-occurring multiple myeloma and lung cancer in a single patient causing spinal cord compression are rarely reported in the literature. We describe a case of a 61-year-old female with multiple myeloma and lung cancer whose radiologic characteristics of spinal cord compression mimicked those of metastatic lung cancer. Finally, the diagnosis was multiple myeloma. We showed the systematic imaging manifestations of metastatic multiple myeloma and discussed their therapeutic management.

Does living at high altitude increase the risk of bleeding events after total knee arthroplasty? A retrospective cohort study.

OBJECTIVE: Post-operative bleeding after total knee arthroplasty (TKA) is a frequent cause of post-operative complications. This study compared blood loss and indicators of coagulation and fibrinolysis between TKA patients living at low or high altitudes. METHODS: We retrospectively analyzed 120 patients at our institution who underwent primary TKA from May 2019 to March 2020, and we divided them into those living in areas about 500 m or > 3000 m above sea level. We compared the primary outcome of total blood loss between them. We also compared them in terms of several secondary outcomes: coagulation and fibrinolysis parameters, platelet count, reduction in hemoglobin, hidden blood loss, intra-operative blood loss, transfusion rate, and incidence of thromboembolic events and other complications. RESULTS: Total blood loss was significantly higher in the high-altitude group than in the low-altitude group (mean, 748.2 mL [95% CI, 658.5-837.9] vs 556.6 mL [95% CI, 496.0-617.1]; p = 0.001). The high-altitude group also showed significantly longer activated partial thromboplastin time, prothrombin time, and thrombin time before surgery and on post-operative day one, as well as increased levels of fibrinogen/fibrin degradation product on post-operative days one and three. Ecchymosis was significantly more frequent in the high-altitude group (41.7 vs 21.7%; relative risk (RR) = 1.923 [95% CI, 1.091-3.389]; p = 0.019). The two groups showed similar transfusion rates, and none of the patients experienced venous thromboembolism, pulmonary embolism, or infection. CONCLUSION: High altitude may alter coagulation and fibrinolysis parameters in a way that increases risk of blood loss after TKA. Such patients may benefit from special management to avoid bleeding events.

Biological Characteristics and Molecular Mechanism of Procymidone Resistance in Stemphylium eturmiunum From Garlic.

Garlic leaf blight caused by Stemphylium eturmiunum was first reported in Jiangsu Province in China. The dicarboximide fungicide (DCF) procymidone is reported to possess broad-spectrum action in inhibiting filamentous fungi and is widely used to control leaf disease of various plants. Of 41 Stemphylium eturmiunum isolates collected in this study from commercial garlic farms in Pizhou and Dafeng counties of Jiangsu Province, eight isolates were resistant to procymidone. The following three phenotypes were categorized according to in vitro responses to DCFs: sensitive, low resistance to iprodione and procymidone, and high resistance to all iprodione and procymidone. The fitness of all resistant isolates was decreased in accordance with data on mycelial growth, conidiation, and virulence. After treatment with 10 µg/ml of procymidone for 4 h, mycelial intracellular glycerol concentrations of resistant isolates were significantly lower than those of sensitive isolates. Positive cross-resistance was observed between dicarboximides and phenylpyrroles, but there was no cross-resistance between dicarboximides and fluazinam or difenoconazole in the two resistant phenotypes. Nucleotide sequence alignment of two-component histidine kinase genes from sensitive and resistant isolates indicated that amino acid mutations were located at the histidine kinase, adenylyl cyclase, methyl-accepting chemotaxis protein and at the phosphatase domain of the N-terminal region and the response regulator domain of the C-terminal region. To our knowledge, this is the first report of DCF resistance in Stemphylium eturmiunum, and these findings will help establish a rational strategy to manage DCF-resistant populations of Stemphylium eturmiunum in the field.

Mutations and Overexpression of CYP51 Associated with DMI-Resistance in Colletotrichum gloeosporioides from Chili.

Chili anthracnose caused by Colletotrichum spp. is an annual production concern for growers in China. Sterol C14-demethylation inhibitors (DMIs, such as tebuconazole) have been widely used to control this disease for more than three decades. In the current study, of 48 isolates collected from commercial chili farms in Jiangsu Province of China during 2018 and 2019, 8 single-spore isolates were identified as Colletotrichum gloeosporioides and the rest were identified as C. acutatum. To determine whether the DMI resistance of isolates develops in the field, mycelial growth of the 48 isolates was measured in culture medium with and without tebuconazole. In all, 6 of the 8 C. gloeosporioides isolates were resistant to tebuconazole, but all 40 of the C. acutatum isolates were sensitive to tebuconazole. The fitness cost of resistance was low based on a comparison of fitness parameters between the sensitive and resistant isolates of C. gloeosporioides. Positive cross-resistance was observed between tebuconazole and difenconazole or propiconazole, but not prochloraz. Alignment results of the CgCYP51 amino acid sequences from the sensitive and resistant isolates indicated that mutations can be divided into three genotypes. Genotype I possessed four substitutions (V18F, L58V, S175P, and P341A) at the CgCYP51A gene but no substitutions at CgCYP51B, while genotype II had five substitutions (L58V, S175P, A340S, T379A, and N476T) at CgCYP51A, concomitant with three substitutions (D121N, T132A, and F391Y) at CgCYP51B. In addition, genotype III contained two substitutions (L58V and S175P) at CgCYP51A, concomitant with one substitution (T262A) at CgCYP51B. Molecular docking models illustrated that the affinity of tebuconazole to the binding site of the CgCYP51 protein from the resistant isolates was decreased when compared with binding site affinity of the sensitive isolates. Our findings provide not only novel insights into understanding the resistance mechanism to DMIs, but also some important references for resistance management of C. gloeosporioides on chili.

Effects of the dinitroaniline fungicide fluazinam on Fusarium fujikuroi and rice.

Fusarium fujikuroi is the primary causal agent of rice bakanae disease. Fluazinam is a protective dinitroaniline fungicide which could interrupt the fungal cell's energy production. Little is known about the effects of fluazinam on F. fujikuroi. In this study, baseline sensitivity of F. fujikuroi to fluazinam was determined using 103 isolates collected from diseased young rice of different fields in Shaoxing of Zhejiang Province and Huaian of Jiangsu Province of China in 2016. The EC50 values of fluazinam on inhibiting mycelial growth against 103 isolates of F. fujikuroi ranged from 0.0621 to 0.5446 µg/mL with the average value of 0.2038 ±â€¯0.0099 µg/mL (mean ±â€¯standard error). The EC50 values of fluazinam on suppressing conidium germination against 103 isolates of F. fujikuroi ranged from 0.1006 to 0.9763 µg/mL with the mean value of 0.3552 ±â€¯0.0181 µg/mL. Treated with fluazinam, hyphae of F. fujikuroi were contorted, offshoot of top mycelia increased, conidial production descreased significantly and exopolysaccharide (EPS) content did not change significantly while peroxidase (POD) activity significantly decreased. Meanwhile, cell membrane permeability increased after treated with fluazinam. The analysis of cell ultrastructure indicated that fluazinam could damage the membrane structure of F. fujikuroi and cause a large number of vacuoles formed. In addition, fluazinam did not affect germination rate, plant height and fresh weight of rice, which indicated that fluazinam was safe to rice. All the results indicated that fluazinam had strong antifungal activity against F. fujikuroi and a potential application in controlling rice bakanae disease. These results will provide useful information for management of rice bakanae disease caused by F. fujikuroi and further increase our understanding about the mode of action of fluazinam against F. fujikuroi and other phytopathogens.

Simultaneous Detection of Multiple Benzimidazole-Resistant ß-Tubulin Variants of Botrytis cinerea using Loop-Mediated Isothermal Amplification.

Optimal disease management depends on the ability to monitor the development of fungicide resistance in plant pathogen populations. Benzimidazole resistance is caused by the point mutations of the ß-tubulin gene in Botrytis cinerea, and three mutations (E198A, E198K, and E198V) at codon 198 account for more than 98% of all resistant strains. Although traditional methods remain a cornerstone in monitoring fungicide resistance, molecular methods that do not require the isolation of pathogens can detect resistance alleles present at low frequencies, and require less time and labor than traditional methods. In this study, we present an efficient, rapid, and highly specific method for detecting highly benzimidazole-resistant B. cinerea isolates based on loop-mediated isothermal amplification (LAMP). By using specific primers, we could simultaneously detect all three resistance-conferring mutations at codon 198. The LAMP reaction components and conditions were optimized, and the best reaction temperatures and times were 60 to 62°C and 45 min, respectively. When B. cinerea field isolates were assessed for benzimidazole resistance, similar results were obtained with LAMP, minimal inhibition concentration, and sequencing. The LAMP assay developed in the current study was highly suitable for detection of highly benzimidazole-resistant field isolates of B. cinerea.

Baseline sensitivity of Bipolaris maydis to the novel succinate dehydrogenase inhibitor benzovindiflupyr and its efficacy.

Benzovindiflupyr is a novel member of succinate dehydrogenase inhibitor (SDHI) fungicides. The filamentous fungus Bipolaris maydis Nisik. et Miyake was the causal agent of southern corn leaf blight (SCLB). Here, baseline sensitivity of B. maydis to benzovindiflupyr was established by mycelial growth and conidium germination methods using 96 B. maydis isolates collected from various places of Jiangsu Province of China, and EC50 values ranged from 0.0321 to 0.9149 µg/ml with the mean value of 0.3446 (±0.2248) µg/ml for mycelial growth, and 0.1864 to 0.964 µg/ml with the mean value of 0.5060 (±0.2094) µg/ml for conidium germination respectively. Treated with benzovindiflupyr, the distribution of nuclei and septum of hyphae did not change, but hyphae of offshoot and conidial production of B. maydis decreased significantly, the cell membrane permeability increased. The result of transmission electron microscope showed that the cross section of hypha was out of shape, the cell wall became thin and sparse, the cell membrane were distinctly damaged, organelles dissolved and vacuolated, and the cell nearly broke up. The results suggested that benzovindiflupyr had strong activity against mycelial growth and conidial production of B. maydis by damaging cell wall, membrane and organelles. The protective and curative activity assays for benzovindiflupyr indicated that benzovindiflupyr exhibited excellent suppression of B. maydis development on detached corn leaves. In protective activity assay with application of benzovindiflupyr at 10 µg/ml, the control efficacy reached to 100%. In curative activity assay with application of benzovindiflupyr at 50 µg/ml, the control efficacy reached to 90.72%. This is the first report of baseline sensitivity of B. maydis to benzovindiflupyr and its biological activity against B. maydis. It is recommended that benzovindiflupyr is a excellent candidate for controlling SCLB.

Molecular and biological characterization of Sclerotinia sclerotiorum resistant to the anilinopyrimidine fungicide cyprodinil.

Cyprodinil belongs to the chemical class of anilinopyrimidines fungicides. In this study, baseline sensitivity of Sclerotinia sclerotiorum (Lib.) de Bary to cyprodinil was determined using 100 strains collected from the fields in Jiangsu Province of China. The EC50 (50% effective concentration) values ranged from 0.0636-0.8163 µg/ml with a mean value of 0.1869 (±0.1118) ug/ml for mycelial growth. Nine cyprodinil-resistant mutants (Range of resistance factor: 20.22-271.59) were obtained from sensitive strains exposed on PDA medium amended with cyprodinil and the resistance was stable after their ten transfers on PDA without the fungicide or stored at 4 °C for two months. There was positive cross-resistance between cyprodinil and pyrimethanil but not to fludioxonil, dimetachlone, procymidone, carbendazim and boscalid in S. sclerotiorum. Compared with the parental strains, all of the nine cyprodinil-resistant mutants decreased in sclerotial production. The dry weight of mycelia, pathogenicity and cell membrane permeability of most resistant mutants decreased. The mycelial growth, oxalic acid content, and the response to various stress for resistant mutants were almost the same as the sensitive parental strains. Sequencing alignment results showed that there was no alteration of amino acid in cystathionine γ-synthase (MetB) and cystathionine ß-lyase (MetC) between cyprodinil-resistant mutants and their sensitive parental strains, which indicated that MetB or MetC was not the molecular target of cyprodinil in S. sclerotiorum. The addition of amino acids L-methionine, L-cystine or L-cysteine decreased the inhibition of cyprodinil against mycelial growth of S. sclerotiorum, which indicated that cyprodinil could not only inhibited methionine biosynthesis but also suppressed cystine and cysteine biosynthesis. These results will contribute to evaluating the resistance risk of cyprodinil for management of the plant diseases of Sclerotinia stem rot caused by S. sclerotiorum and further increase our understanding about the mode of action of cyprodinil.

Resistance risk assessment for fluazinam in Sclerotinia sclerotiorum.

In the current study, sensitivity distribution of Sclerotinia sclerotiorum populations to fluazinam was determined using 103 strains collected from the fields of Jiangsu Province of China in 2016-2017 and the resistance risk of fluazinam was assessed. The average EC50 (50% effective concentration) values and MIC (minimum inhibitory concentration) values of 103 S. sclerotiorum strains against fluazinam were 0.0073±0.0045µg/ml and <0.3µg/ml for mycelial growth, respectively. Nine mutants with low resistance level were obtained from wild type sensitive strains exposed on PDA medium amended with fluazinam and the resistance was stable after their ten transfers on PDA without the fungicide. Compared with the parental strains, the nine fluazinam-resistant mutants decreased in mycelial growth, sclerotial production, pathogenicity and were more sensitive to 0.7M NaCl. In addition, cell membrane permeability of resistant mutants was higher than that of their parental strains. Cross resistance assay showed that there was no cross-resistance between fluazinam and fludioxonil, dimetachlone, prochloraz, tebuconazole, azoxystrobin, or procymidone in S. sclerotiorum. The above results indicated that there was a low resistance risk for fluazinam in S. sclerotiorum. However, the sensitivity of all fluazinam-resistant mutants to fludioxonil decreased. Sequencing alignment results showed that there were no mutations in the two-component histidine kinase gene (Shk1) of the resistant mutants and the expression levels of Shk1 of three resistant mutants were significantly up-regulated while others were almost the same as their parental strains. These results will contribute to evaluating the resistance risk of fluazinam for management of diseases caused by S. sclerotiorum and further increase our understanding about the mode of action of fluazinam.

Resistance mechanism of Fusarium fujikuroi to phenamacril in the field.

BACKGROUND: Rice bakanae disease, mainly caused by Fusarium fujikuroi, is an important disease of rice. Phenamacril has been used to control the disease for a few years in China. In 2016, nine phenamacril-resistant strains were found in the field in Zhejiang Province. The aim of the study was to clarify the mechanism of resistance of F. fujikuroi to phenamacril and the fitness of resistant strains. RESULTS: The nine F. fujikuroi strains examined were highly resistant to phenamacril. Eight of them had the point mutation TCA (Ser) → CCA (Pro) at codon 219 in the Myosin-5 protein, while the other had the point mutation TCA (Ser) → TTA (Leu) at codon 219. Myosin-5 replacement between resistant and sensitive strains confirmed that the point mutation in Myosin-5 caused the resistance of F. fujikuroi to phenamacril. Docking of phenamacril into the modeled binding pocket of Myosin-5 showed that the affinity between phenamacril and Myosin-5 decreased and a hydrogen bond could not be formed between phenamacril and the amino acid at codon 219 after it changed to Pro or Leu. There was no cross-resistance between phenamacril and other fungicides. The eight resistant strains containing the point mutation S219P had almost the same fitness as the sensitive strains, while the one resistant strain containing the point mutation S219 L showed decreased mycelial growth, sporulation and pathogenicity. CONCLUSION: In the field, the point mutation S219P or S219 L in Myosin-5 conferred high resistance to phenamacril in F. fujikuroi. The point mutation S219P did not affect the fitness of F. fujikuroi, while the point mutation S219 L decreased its fitness. © 2017 Society of Chemical Industry.

Endothelial Aquaporin-1 (AQP1) Expression Is Regulated by Transcription Factor Mef2c.

Aquaporin 1 (AQP1) is expressed in most microvasculature endothelial cells and forms water channels that play major roles in a variety of physiologic processes. This study aimed to delineate the transcriptional regulation of AQP1 by Mef2c in endothelial cells. Mef2c cooperated with Sp1 to activate human AQP1 transcription by binding to its proximal promoter in human umbilical cord vein endothelial cells (HUVEC). Over-expression of Mef2c, Sp1, or Mef2c/Sp1 increased HUVEC migration and tube-forming ability, which can be abolished AQP1 knockdown. These data indicate that AQP1 is a direct target of Mef2c in regulating angiogenesis and vasculogenesis of endothelial cells.

Transfer of the beta-tubulin gene of Botrytis cinerea with resistance to carbendazim into Fusarium graminearum.

BACKGROUND: Resistance to carbendazim and other benzimidazole fungicides in Botrytis cinerea (Pers. ex Fr.) and most other fungi is usually conferred by mutation(s) in a single chromosomal beta-tubulin gene, often with several allelic mutations. In Fusarium graminearum Schwade, however, carbendazim resistance is not associated with a mutation in the corresponding beta-tubulin gene. RESULTS: The beta-tubulin gene conferring carbendazim resistance in B. cinerea was cloned and connected with two homologous arms of the beta-tubulin gene of F. graminearum by using a double-joint polymerase chain reaction (PCR). This fragment was transferred into F. graminearum via homologous double crossover at the site where the beta-tubulin gene of F. graminearum is normally located (the beta-tubulin gene of F. graminearum had been deleted). The transformants were confirmed and tested for their sensitivity to carbendazim. CONCLUSION: The beta-tubulin gene conferring carbendazim resistance in B. cinerea could not express this resistance in F. graminearum, as transformants were still very sensitive to carbendazim.

Multiple Resistance of Botrytis cinerea from Vegetable Crops to Carbendazim, Diethofencarb, Procymidone, and Pyrimethanil in China.

One hundred and eight isolates of Botrytis cinerea from greenhouse cucumber and tomato in two locations in Jiangsu Province (Nanjing and Huaiyin) and one location in Shandong Province were tested for their sensitivities to the four fungicides commonly used in China. Isolates with resistance to all four fungicides-carbendazim, diethofencarb, procymidone, and pyrimethanil (CarRDieRPrcRPyrR)-were found in all three regions in this study. High frequencies (52 and 53%) of resistance to all four fungicides were observed among the 62 isolates collected in Nanjing and the 36 isolates collected in Huaiyin in Jiangsu Province. The 10 isolates from Shandong Province were all resistant to the four fungicides. Pathogenicity and sporulation in vivo, and mycelial growth, sporulation, spore germination, and osmotic sensitivity to NaCl in vitro, were similar for the group of quadruple-resistant and wild-type isolates (P > 0.05). In the present study, the complete two-component histidine kinase gene (Bos1) was sequenced for 10 procymidone-resistant and 3 procymidone-sensitive B. cinerea isolates. Isolates representing four different procymidone-resistant phenotypes (CarRDieSPrcRPyrS, CarRDieRPrcRPyrS, CarRDieRPrcRPyrR, and CarRDieRPrcRPyrR) all had nucleic acid point mutations resulting in amino acid changes at position 369 (change from glutamine to proline) as well as at amino acid position 373 (asparagine to serine) in the Bos1 gene.

Mutations in a beta-tubulin confer resistance of Gibberella zeae to benzimidazole fungicides.

ABSTRACT Wheat head blight caused by Gibberella zeae (anamorph: Fusarium graminearum) is a threat to food safety in China because of mycotoxin contamination of the harvested grain, the frequent occurrence of the disease, and the failure of chemical control in some areas due to benzimidazole resistance in the pathogen population. The molecular resistance mechanism, however, of G. zeae to benzimidazole fungicides (especially carbendazim; active ingredient: methyl benzimidazol-2-yl carbamate [MBC]) is poorly understood. DNA sequences of a beta-tubulin gene (beta(2)tub) (GenBank access number FG06611.1) in G. zeae were analyzed. Mutations in beta(2)tub in moderately resistant strains (MBC(MR)) included TTT (Phe)-->TAT (Tyr) at codon 167 or TTC (Phe)-->TAC (Tyr) at codon 200. A highly resistant strain (MBC(HR)) had two point mutations, one at codon 73, CAG (Gln)-->CGG (Arg), and the other at codon 198, GAG (Glu)-->CTG (Leu). To confirm that mutations in the beta(2)tub confer resistance to benzimidazole fungicides, the entire beta(2)tub locus was deleted from MBC(MR) and MBC(HR) strains of G. zeae. The resulting Deltabeta(2)tub mutants from both MBC(MR) and MBC(HR) strains grew normally on MBC-free potato dextrose agar medium and were supersensitive to MBC. Complementation of the Deltabeta(2)tub mutants by transformation with a copy of the intact beta(2)tub locus from their parent strains exhibited less resistance than the original strains, and complementation of the Deltabeta(2)tub mutants by transformation with a copy of the intact beta(2)tub locus from sensitive strains restored MBC sensitivity. The results indicated that the mutations in the beta(2)tub gene conferred resistance of G. zeae to benzimidazole fungicides and this gene can be used as a genetic marker in G. zeae.

Occurrence and Characterization of Dimethachlon Insensitivity in Sclerotinia sclerotiorum in Jiangsu Province of China.

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is the main fungal disease of oilseed rape (Brassica napus) in China. Numerous fungicide applications are required for control. Dimethachlon, one of the dicarboximide fungicides, has been the major fungicide for disease control after benzimidazole resistance became widespread. Fungal populations were collected throughout Jiangsu Province between 2006 and 2007 in order to determine their sensitivity to dimethachlon. A total of 1,066 single-sclerotium isolates of S. sclerotiorum were collected, and most of the isolates were considered sensitive to dimethachlon. Five isolates collected in Yancheng and Changzhou showed normal growth at 5 µg/ml dimethachlon with the resistance factor ≈10 (resistance factor was estimated as ratios between the EC50 values of resistant isolates and the average EC50 values of sensitive ones) compared to the sensitive isolates (EC50 is the concentration of fungicide causing 50% reduction in growth). Through in vitro selection for resistance to the fungicide, 25 dimethachlon-resistant mutants were derived from 10 wild-type isolates of S. sclerotiorum. The resistance factors for the isolates ranged from 198 to 484, and the isolates were considered highly resistant to dimethachlon. Therefore, at least two different mechanisms of resistance seem to be involved: one that may provide a moderate resistance (insensitivity) and a second that may give a high resistance level under laboratory conditions. There was positive cross-resistance between dimethachlon and other dicarboximide fungicides, such as iprodione and procymidone, in these S. sclerotiorum isolates. The field dimethachlon-insensitive and the laboratory-induced dimethachlon-resistant isolates appeared to have mycelial growth, sclerotial production, and pathogenicity comparable to their wild-type parental isolates. Also, results of osmotic tests showed that there were no significant difference in mycelial radial growth between the field dimethachlon-sensitive and field dimethachlon-insensitive isolates on potato dextrose agar plates amended with 2, 4, 6, or 8% (wt/vol) NaCl, but the laboratory-induced dimethachlon-resistant isolates grew significantly more slowly than their wild-type sensitive parents under all concentrations of NaCl. Because these studies yielded a high frequency of laboratory resistance in S. sclerotiorum, together with the occurrence of field insensitivity, appropriate precautions against resistance development in natural populations should be taken.