西洋参种子分离真菌的致病性测定及杀菌剂对种传病原真菌的生物测定

目的 :测定西洋参种子分离真菌的致病性 ,并筛选对西洋参种传病原真菌有效的新型杀菌剂。方法 :幼苗期接种测定对西洋参的致病性 ,平皿菌丝生长抑制法进行杀菌剂的生物测定。结果 :镰刀菌Fusarium sp .5号菌株和链格孢菌Alternaria sp .13号菌株对西洋参幼苗能致病。 3种杀菌剂中 ,施保克对 2种致病菌的抑制作用最强 ,多菌灵次之 ,适乐时的抑菌作用相对弱一些。结论 :施保克和适乐时可作为有效的候选药剂用于西洋参种子的药剂处理或种子包衣 ,替代生产上已使用多年的多菌灵 ,用来防治西洋参苗期病害。     

Effects of tetramethylthiuram disulphide (thiram) on adenine nucleotide (ATP,ADP, AMP) levels in the ciliate Tetrahymena pyriformis

Axenic cultures of Tetrahymena pyriformis GL populations were exposed to 0.40 μg/mL of tetra methylthiuram disulphide (TMTD). Doubling times and ATP, ADP and AMP levels were followed on control and treated populations at various cell densities during the exponential growth phase. For the control populations, the average generation time was 171.9 min and ATP levels were 2–8×10⁻¹⁴ mol/cell. For the treated populations, growth was reduced and the populations with the highest densities were more sensitive than populations treated with TMTD at the early stage of the exponential growth phase. For treated populations, ATP and ADP concentrations showed significant differences compared to the control populations. Mechanisms compensating the action of the TMTD have been observed with treated populations at 25,000 cells/mL density. Unfortunately AMP levels were unstable within control populations showing no differences with those from treated populations. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 409–413, 1999     

Antifungal activity of alkanols against Zygosaccharomyces bailii and their effects on fungal plasma membrane

A series of aliphatic primary alkanols from C(6) to C(13) were tested for antifungal activity against a food spoilage fungus Zygosaccharomyces bailii using a broth dilution method and were compared for their effects against Saccharomyces cerevisiae and Z. rouxii. Decanol (C(10)) was found to be the most potent fungicide against Z. bailii at a minimum fungicidal concentration of 50 microg/ml (0.31 mM), whereas undecanol (C(11)) was found to be the most potent fungistatic at a minimum inhibitory concentration of 25 microg/ml (0.14 mM). The time-kill curve study showed that decanol was fungicidal against Z. bailii at any growth stage. Octanol (C(8)) increased plasma membrane fluidity in the spheroplast cells of S. cerevisiae. The primary antifungal action of alkanols comes from their ability to disrupt the native membrane-associated function of integral proteins nonspecifically as nonionic surface-active agents (surfactants). The antifungal activity of decanol against Z. bailii was slightly enhanced in combination with anethole.     

防霉剂药效测试方法初探

目的为防霉剂的药效评价寻找一种准确、可靠的检测方法。方法采用沙氏琼脂培养基,在相对湿度约92%的干燥器内,对3种剂量的防霉剂(96%对二氯苯)进行防霉效果的观察,根据培养基表面积的霉变比率对其防霉效果做出评价。结果用药量在0、25、50、100 g/m3时,培养基的霉变率达到90%的时间(d)分别为3、7、14 d和大于14 d。结论此检测方法操作简便、规范,结果准确,易于判别,能够比较客观地反映出检测样品的剂效关系。     

Allergic contact dermatitis from ethylene thiourea

A case of allergic contact dermatitis to the rubber additive material ethylene thiourea (ETU) is presented. Testing for cross-sensitivity gave a positive reaction to the fungicide Maneb®, manganous ethytenebisdithiocarbamte, but this reaction was probably due to ETU which was detected in Maneb® by thin-layer chromatography. Different sources of ETU arc reported.     

Ultraviolet induction of antifungal activity in plants

Ultraviolet‐C irradiation as a method to induce the production of plant compounds with antifungal properties was investigated in the leaves of 18 plant species. A susceptibility assay to determine the antifungal susceptibility of filamentous fungi was developed based on an agar dilution series in microtiter plates. UV irradiation strongly induced antifungal properties in five species against a clinical Fusarium solani strain that was responsible for an onychomycosis case that was resistant to classic pharmacological treatment. The antifungal properties of three additional plant species were either unaffected or reduced by UV‐C irradiation. This study demonstrates that UV‐C irradiation is an effective means of modulating the antifungal activity of very diverse plants from a screening perspective.     

Botanical and chemical fungicides in the treatment of commercial seeds of Brachiaria brizantha and Panicum maximum

Brazil is the largest producer, consumer, and exporter of forage seeds in the world. However, the high incidence of pathogens threatens the seed production system, resulting in decreases in production and quality. Currently, the emphasis has been placed on the use of alternative products as a way of maintaining productivity and environmental sustainability. Thus, the objective of this study was to evaluate the mycoflora associated with the commercial seeds of Brachiaria brizantha and Panicum maximum treated with chemical and alternative fungicide. To test with chemical and alternative treatments, seeds were subjected to fluazinam + thiophanate-methyl, fludioxonil + metalaxyl-M, noni essential oil, rosemary pepper essential oil, sulfuric acid. There was also an untreated control. The most efficient products in the control of incident fungi were, in decreasing order, fluazinam + thiophanate-methyl, fludioxonil + metalaxyl-M, noni essential oil, rosemary pepper essential oil, and sulfuric acid. Fungicides mainly controlled the genera Alternaria, Aspergillus, Bipolaris, Chaetomium, Cladosporium, Colletotrichum, Curvularia, Fusarium, Penicillium, Phoma and Rhizopus. Essential oils showed positive effects in controlling Bipolaris, Curvularia, and Fusarium. Sulfuric acid reduced the incidence of Bipolaris, Colletotrichum, Curvularia, Fusarium, Phoma, and Rhizopus. Seed treatment is one of the promising strategies for obtaining seeds of a healthy quality. As a result, the fungicides and botanical components listed above were promising in reducing fungi associated with forage seeds and can be used for seed treatments and in the development of new products with a natural base through essential oils.     

Subchronic and chronic toxicological investigations on metiram: the lack of a carcinogenic response in rodents.

Metiram complex is a non-systemically acting fungicide of the group of ethylenebisdithiocarbamates (EBDC). The subchronic and chronic toxicity and the carcinogenic potential of metiram (containing 2% ethylene thiourea, ETU, as an intentionally added impurity) were investigated. Doses in the chronic/carcinogenicity rat study were 0, 5, 20, 80, or 320 ppm. In the carcinogenicity study in mice, diets were administered for 89 weeks (females) or 95 weeks (males) at doses of 0, 100, 300, or 1000 ppm. No oncogenic response was noted in either species. The subchronic studies in rats and mice further investigated the thyroid as a target organ. Doses of 0, 5, 80, 320, or 960 ppm were utilized in the rat study and a NOAEL of 80 ppm was established. In the subchronic mouse study, diets containing 0, 300, 1000, 3000, or 7500 ppm were utilized. A NOAEL of 300 ppm was established in this study. In summary, the findings of these studies defined the toxicity of metiram in rodents and demonstrated the lack of a carcinogenic response following chronic dietary exposure in the rat and mouse. The NOAELs that were established in these studies were consistent with the NOAELs established for thyroid toxicity/carcinogenicity in studies on ethylenethiourea (ETU).