积雪草漆斑病病原鉴定及室内药剂筛选

近年来,在广西各地积雪草种植基地,出现一种为害极重的病害,该病害病原菌主要为害积雪草叶片、叶柄,可致使叶片大面积枯死,该病害发生普遍、侵染期长,严重影响积雪草药材的品质和产量。该研究采用常规组织分离法从积雪草病叶上分离病原菌并根据柯赫氏法则验证其致病性;通过菌落特征、菌株形态及ITS序列分析鉴定病原菌;在室内利用生长速率法测定10种杀菌剂对该菌的抑制活性。结果表明：为害积雪草叶片的病原菌为泛生漆斑菌( Myrothecium inundatum);该菌侵染性强,接种至健康积雪草叶片后24 h即可发病,并迅速扩展引起叶片萎蔫;杀菌剂60％唑醚?代森联水分散粒剂、45％恶霉灵?甲霜可湿性粉剂、1.8％辛菌胺醋酸盐水剂、80％代森锰锌可湿性粉剂室内对积雪草漆斑病病原菌的抑菌率均在98％以上,抑菌效果极强,建议在生产中轮换应用防治积雪草漆斑病。15％咪鲜胺微乳剂、70％甲基硫菌灵可湿性粉剂和10％苯醚菌酯悬浮剂对该病原菌的抑菌率也均在92％以上,抑菌效果良好,在生产中可酌情考虑使用。     

Antifungals: Mold control and safe levels in artificial media forTrichogramma [Hymenoptera: Trichogrammatidae]

Ten chemicals known to be fungicides are tested in artificial media forTrichogramma dendrolimi Matsu. [Hymenoptera: Trichogrammatidae]. Tests are performed in France by using artificial host egg capsules. Most of the fungicides cannot control fungus or are toxic forTrichogramma at effective levels. Geneticin, Amphotericin B and Nystatin, used at proper levels are able to control molds efficiently without modifyingTrichogramma development. These antifungals are also tested in actual conditions of mass production, in Guangzhou (China).      

A comparison ofin vitro andin vivo effect of clay minerals,humic acid and micronutrients on the activity of fungicides againstRhizoctonia solani

Activity of nine fungicides against mycelial growth ofRhizoctonia solani in potato dextrose broth and in pot tests as seed treatment against cowpea seedling rot in infested soil was differentially in fluenced by clay minerals, humic acid and micronutrients. Humic acid, extracted from farmyard manure, considerably lowered the activity, bothin vitro andin vivo, of all fungicides except chloroneb. Montmorillonite caused substantial decrease in disease control by fungicides but enhanced the toxicity of 2-methoxyethyl mercury chloride (MEMC), and quintozene in culture. Kaolinite inactivated carbendazim, benomyl and thiophanatemethyl in nutrient broth but had little effect on disease control by these fugicides. The six micronutrients altered the activity of fungicides to varying levels often without definite correlation betweenin vitro andin vivo results. The results ofin vitro growth inhibition tests are largely inapplicable to dieseas control tests in infested soil mainly due to the differences in the ambient conditions of the two systems.     

Fungicide inhibition of aflatoxins,diacetoxyscirpenol and zearalenone production

The effect of fungicides on the production of aflatoxin byAspergillus flavus IMI 89717, diacetoxyscirpenol and zearalenone byFusarium graminearum was studied. In a yeast extract - sucrose medium, dicloran, iprodione and vinclozolin fungicides significantly inhibited mycelial growth ofA. flavus at 250 ppm and significantly decreased aflatoxin production at 100, 250 and 500 ppm, respectively. In potato — dextrose broth, these fungicides diminished the mycelial growth ofF. graminearum and production of diacetoxyscirpenol and zearalenone at 100 ppm. Sensitivity of toxigenic mycelia to fungicides increased approximately five-fold in a yeast extract-starch medium with an appreciable reduction in sugar uptake andα-amylase activity.     

Compatibility of Chemical Disease and Insect Management Practices Used in New York Vineyards with Biological Control by Anagrus spp. (Hymenoptera: Mymaridae), Parasitoids of Erythroneura Leafhoppers

Toxicity to Anagrus spp. of fungicides and insecticides used in grape production was assessed with laboratory and field bioassays. Field-equivalent rates of fungicides were relatively nontoxic to Anagrus spp. adults in laboratory bioassays. In bioassays with field-weathered residues, sulfur (9600 ppm) caused elevated mortality of adults for 14 to 21 days posttreatment. Residues of microencapsulated methyl parathion (600 and 1200 ppm) increased mortality relative to the control up to 43 days posttreatment. Duration of elevated mortality of adults exposed to carbaryl was dose dependent and ranged from 14 (at 1200 ppm) to >43 days (at 4800 ppm). Residues of carbaryl and methyl parathion applied over parasitized eggs had little effect on emergence, but may have delayed development. In a field trial, adults trapped in carbaryl-treated plots were significantly reduced starting 3 weeks after treatment. Subsequent lower trap catches may have been related to effects of residues on Anagrus spp. adults or to lower leafhopper egg densities in treated plots.     

Laboratory method for testing side-effects of pesticides on the rove beetleAleochara bilineata — Adults

Tests were conducted in glass cells containing moistened sand sprayed with the concentration recommended for the pesticide or with demineralised water (controls). Adult females (1–2 weeks old) ofA. bilineata were placed on the fresh residue in the cells and provided daily with fresh fly eggs as food. The duration of the test was 5 days, mortality being recorded every day. The side effects of the pesticide were expressed as reduction in egg production ofA. bilineata during the whole test period. Results permitted classification of the pesticides according to the 4 categories of harmfulness used by the IOBC working group. 23 pesticides were tested, and the reproducibility of the test appeared to be satisfactory. Generally, insecticides/acaricides had a pronounced effect on the beetles whereas fungicides and herbicides were less detrimental. Exceptions were the insecticides Tedion V 18 and Kilval, classified as harmless, and the fungicides Morestan, Pomarsol forte and Afugan rated as moderately harmful. Among growth regulators Prosevor 85 was highly detrimental while Cycocel Extra and Rhodofix had no effects. Excepting Morestan, Pomarsol forte and Ustinex PA the pesticides did not affect the hatching of eggs. The work was financed by the Danish Environmental Protection Agency.     

A comparison of the effect of three fungicides on growth and roridin E production by Myrothecium roridum

Three fungicides, chlorothalonil, dichloran and mancozeb were studied to determine the effects on growth and production of roridin E by Myrothecium roridum in vitro. With increasing concentrations of fungicides, both growth and production of roridin E were inhibited. Of the three fungicides, chlorothalonil was much more effective in the inhibition of growth and production of roridin E, than dichloran and mancozeb.     

Cloning and characterization of the histidine kinase gene<Emphasis Type="Italic"> Dic1</Emphasis> from<Emphasis Type="Italic"> Cochliobolus heterostrophus</Emphasis> that confers dicarboximide resistance and osmotic adaptation

A gene for a putative two-component histidine kinase, which is homologous to os-1 from Neurospora crassa, was cloned and sequenced from the plant-pathogenic fungus Cochliobolus heterostrophus. The predicted protein possessed the conserved histidine kinase domain, the response regulator domain, and six tandem repeats of 92-amino-acids at the N-terminal end that are found in histidine kinases from other filamentous fungi. Introduction of the histidine kinase gene complemented the deficiency of the C. heterostrophus dic1 mutant, suggesting that the Dic1 gene product is a histidine kinase. Dic1 mutants are resistant to dicarboximide and phenylpyrrole fungicides, and they are sensitive to osmotic stress. We previously classified dic1 alleles into three types, based on their phenotypes. To explain the phenotypic differences among the dic1 mutant alleles, we cloned and sequenced the mutant dic1 genes and compared their sequences with that of the wild-type strain. Null mutants for Dic1, and mutants with a deletion or point mutation in the N-terminal repeat region, were highly sensitive to osmotic stress and highly resistant to both fungicides. A single amino acid change within the kinase domain or the regulator domain altered the sensitivity to osmotic stress and conferred moderate resistance to the fungicides. These results suggest that this predicted protein, especially its repeat region, has an important function in osmotic adaptation and fungicide resistance.Communicated by C. A. M. J. J. van den Hondel     

Efficacy of Milsana®, a Formulated Plant Extract from Reynoutria sachalinensis, against Powdery Mildew of Tomato (Leveillula taurica)

The efficacy of Milsana^® VP 1999 and 2000 (a formulated plant extract of Reynoutria sachalinensis), known to induce resistance to powdery mildew on cucumbers, was tested against Leveillula taurica (Lév.) Arn. on greenhouse tomato. In four out of five trials, Milsana^® achieved a disease reduction ranging from 42.2 to 64.6%. In one trial only, its efficacy was exceptionally low (23%). Application rates and disease pressure proved to be the main factors affecting the level of control. Milsana^® was significantly less effective than fungicides (alternated DMIs and penconazole) in situ. In contrast, Milsana^® was equally effective to wettable sulphur indicating that its effect was rather preventive than curative. The level of efficacy achieved by either Milsana^® or fungicides did not result in a significant increase of yield. Laboratory tests showed that Milsana^® (VP 1999) had a direct effect on conidial germination. Whether this effect significantly contributes to its field efficacy, remains to be elucidated. Overall, results indicate that Milsana^® could play an important role in disease management of powdery mildew in organic and low input tomato production.     

Comparison among four triazole fungicides on growth and development of sheath blight of rice pathogen Rhizoctonia solani Kühn AG1-1A

The sheath blight of rice pathogen Rhizoctonia solani Kühn AG1-1A has long been known as a major crisis in global rice production. The present study aimed to compare the efficacy of four triazole fungicides at different doses on the growth and development of R. solani Kühn AG1-1A. Obtained results demonstrated inhibitory effects of all four fungicides on mycelial growth, sclerotia formation and biomass production of R. solani Kühn AG1-1A with significant variation among the treatment doses as well as fungicide molecules (p ≤ 0.05). At the respective EC₅₀ doses all four fungicides inhibited cell wall degrading enzymes viz. invertase, cellulase, polygalacturonase and pectin lyase, of the sheath blight pathogen. The extent of inhibition of the enzymes significantly varied among the fungicides. It is important to note that in spite of having common mode of action, all four triazole fungicides demonstrated significant variation in their fungicidal efficacy on R. solani Kühn AG1-1A.     

Biocontrol of tomato late blight with the combination of epiphytic antagonists and rhizobacteria

Control of tomato late blight (LB) in Brazil is heavily based on chemicals. However, reduction in fungicide usage is required in both conventional and organic production systems. Assuming that biological control is an alternative for LB management, 208 epiphytic microorganisms and 23 rhizobacteria (RB) were isolated from conventional and organically grown tomato plants and tested for antagonistic activity against Phytophthora infestans. Based on in vitro inhibition of sporangia germination and detached leaflet bioassays, four EP microorganisms (Aspergillus sp., Cellulomonas flavigena, Candida sp., and Cryptococcus sp.) were selected. These microorganisms were applied either singly or combined on tomato plants treated or not with the RB Bacillus cereus. On control plants, LB progress rate (r), area under disease progress curve, and final disease severity were high. Lowest values of final severity were recorded on plants colonized by B. cereus and treated with C. flavigena, Candida sp. and Cryptococcus sp. There was no reduction on disease severity in plants treated only with RB. Biological control of LB resulted in low values of r and final severity. Integration of biological control with fungicides, cultural practices, and other measures can contribute to manage LB on tomato production systems.     

Ethylene formation by germinating,Drechslera graminea — Infected barley (Hordeum sativum) grains: A simple test for fungicides

Grains of barley (Hordeum sativum L.); infected with the parasitic, systemic fungus Drechslera graminea, produce more ethylen than uninfected controls. Treatment of infected grains with mercury-free fungicides yields a differentiated suppression of the ethylene evolution 7 d after the beginning of germination. Suppression of visible symptoms (chlorotic stripes on leaves) appearing six to eight weeks after germination of infected, untreated seeds correlates with the decrease in ethylene formation after treatment with fungicides. The gaschromatographic ethylene determination thus allows for an early and reliable (significance higher than 99.9%) differentiation of fungicidal activities against the barley stripe disease.Abbreviations ACC I-aminocyclopropane-1-carbonic acid - CD critical difference     

Effect of fungicides on survival of Rhizobium on seeds and the nodulation of bean (Phaseolus vulgaris L.)

The survival of Rhizobium leguminosarum biovar phaseoli on seeds of bean was tested, using the cultivar Carioca. The seeds were treated seven days before inoculation with Benlate, Vitavax, Banrot, Difolatan or Ridomil fungicides. The rhizobial strains used were: CIAT 899, CPAC 1135 and CIAT 652. Strain CIAT 899 showed greater survival on the seed with fungicide than the other strains. Two hours after the contact with fungicides strains CIAT 652 and CPAC 1135 had significantly lower numbers of rhizobia than the treatment without fungicide. The Benlate and Banrot fungicides had the greatest effect on survival of rhizobial strains. There was a drastic mortality of the two strains, CIAT 652 and CPAC 1135, on seeds treated with Benlate and Ridomil. Under field conditions, granular inoculation produced fewer nodules, but a similar total nodule weight as seed inoculation. Serological tests (ELISA) showed that seed treatment with Benlate in connection with seed inoculation reduced drastically the occurrence of inoculated strains in nodules, while the same fungicide treatment and inoculation applied in the seed furrow did not affect the survival of the inoculated strain.     

Potential of genes and gene products fromTrichoderma sp. andGliocladium sp. for the development of biological pesticides

Fungal cell wall degrading enzymes produced by the biocontrol fungiTrichoderma harzianum andGliocladium virens are strong inhibitors of spore germination and hyphal elongation of a number of phytopathogenic fungi. The purified enzymes include chitinolytic enzymes with different modes of action or different substrate specificity and glucanolytic enzymes with exo-activity. A variety of synergistic interactions were found when different enzymes were combined or associated with biotic or abiotic antifungal agents. The levels of inhibition obtained by using enzyme combinations were, in some cases, comparable with commercial fungicides. Moreover, the antifungal interaction between enzymes and common fungicides allowed the reduction of the chemical doses up to 200-fold. Chitinolytic and glucanolytic enzymes fromT. harzianum were able to improve substantially the antifungal ability of a biocontrol strain ofEnterobacter cloacae. DNA fragments containing genes encoding for different chitinolytic enzymes were isolated from a cDNA library ofT. harzianum and cloned for mechanistic studies and biocontrol purposes. Our results provide additional information on the role of lytic enzymes in processes of biocontrol and strongly suggest the use of lytic enzymes and their genes for biological control of plant diseases.     

工厂化生产海鲜菇菌包污染霉菌的鉴定及防治

对工厂化生产中海鲜菇菌包污染霉菌进行分离,根据霉菌的形态特征、培养性状及ITS序列分析,鉴定其为哈茨木霉、拟康氏木霉、脉孢霉、长枝木霉、黑曲霉、产红青霉和产黄青霉;在此基础上探讨了常用抑菌剂对霉菌的防治效果及对海鲜菇菌丝生长的影响。结果表明,质量浓度100 mg/L克霉灵对哈茨木霉、黑曲霉、产红青霉、产黄青霉、拟康氏木霉有强抑制作用,质量浓度100 mg/L多菌灵对长枝木霉、产红青霉、产黄青霉、拟康氏木霉有强抑制作用,二者对海鲜菇菌丝生长的抑制都比较弱。可为海鲜菇工厂化生产中污染霉菌的综合防治提供参考。     

Iturin A: A potential new fungicide for stored grains

The removal of many synthetic fungicides from the market has created a demand for new, environmentally safe fungicides. Iturin A, a cyclic lipopeptide produced byBacillus subtilis, has strong antifungal properties and low mammalian toxicity. To determine the efficacy of this compound as a potential fungicide on stored feed grains, lots of corn, peanuts and cottonseed were treated with varying concentrations of iturin A. The mycoflora of treated seed was assayed along with that of untreated seed and seed treated with fungicides used commercially for planting seed. Fungal species varied considerably in their sensitivity to iturin A. Significant reductions in total mycoflora occurred in most seed lots tested at iturin A concentrations of 50 to 100 ppm.     

Assessing in vitro efficacy of certain fungicides to control Sclerotinia sclerotiorum in peanut

The fungal pathogen Sclerotinia sclerotiorum is responsible for Sclerotinia blight in several crops around the world, including peanut. This study was conducted under laboratory conditions to determine the effects of four registered fungicides, Propulse?, Fontelis^®, Omega^® and Endura^® on mycelial growth and pigmentation, as well as sclerotia and oxalic acid production on a growth medium modified with a fungicide and on the pathogenicity of S. sclerotiorum on leaflets detached from Valencia peanut. Propulse, Omega and Fontelis inhibited mycelial growth of S. sclerotiorum, while, mycelial growth on a modified support with Endura was similar to the control treatment. All fungicides, except Endura, inhibited the production of oxalic acid. Pigmentation of the mycelium was observed in both the control and endura treatments. Sclerotia production was observed only in the control treatment. With the exception of Endura, all fungicides were effective in controlling the development of lesions on Valencia peanut leaflets.     

In vitro sensitivity of Verticillium fungicola to selected fungicides

Twenty isolates of Verticillium fungicola var. fungicola collected from diseased fruit-bodies of Agaricus bisporus from prochloraz-treated crops, were exposed to a range of concentrations of six chemicals (benomyl, chlorothalonil, formaldehyde, iprodione, prochloraz-Mn-complex and prochloraz + carbendazim) in vitro. EC₅₀ values were determined for each fungus-fungicide combination. All isolates were more sensitive to prochloraz-Mn-complex (EC₅₀ values less than 5 mg 1^–1) than to the remainder fungicides, and only seven isolates were moderately sensitive (EC₅₀ values between 5 and 50 mg 1^–1) to prochloraz + carbendazim. All isolates were moderately sensitive to formaldehyde, whereas the majority of isolates were very resistant to the other three fungicides (benomyl, chlorothalonil and iprodione).     

In vitro studies on the effects of fungicides on beneficial fungi of peach twig mycoflora

In vitro studies were carried out to investigate a possible integrated use of chemical and biological means to control the peach twig blight pathogen,Monilinia laxa. Three fungal antagonists ofM. laxa (Penicillium purpurogenum, Penicillium frequentans andEpicoccum nigrum) and six fungicides (vinclozolin, iprodione, thiram, captan, benomyl and thiophanate-methyl) were used in the study. Sensitivity of the fungal isolates to the fungicides was determined in vitro by calculating ED50 values. Benomyl and thiophanate-methyl were the most fungitoxic compounds and captan was the least fungitoxic.M. laxa andP. purpurogenum were the most sensitive to all chemicals tested, whileE. nigrum andP. frequentans presented bigger differences in their sensitivity to chemicals compared toM. laxa. E. nigrum was consistently less sensitive to benomyl (ED50=2.26 ppm), thiophanate-methyl (ED50=9.61 ppm) and vinclozolin (ED50=3.89 ppm) than the other fungi.P. frequentans was less sensitive to captan, vinclozolin, iprodione, thiophanate-methyl and thiram thanM. laxa (8, 7, 5, 4 and 2 times respectively). These results suggest thatE. nigrum andP. frequentans could be successfully used in an integrated control programme that combines biological and chemical methods.     

Effects of 37 fungicides on the rove beetleAleochara bilineata (Col.: Staphylinidae) in the laboratory

Effects of 37 fungicides — several of which were mixtures — on adult females of the rove beetle,Aleochara bilineata, were investigated in the laboratory. The pesticides were tested in concentrations equivalent to the highest recommended dosages for practical use. Mortality, egg production and hatch of the eggs were recorded. Most fungicides had no serious effect on any of the parameters measured. Among the morpholine and dithiocarbamate fungicides, several had adverse effects on egg production and/or hatch of the eggs laid. Furthermore, chinomethionate and pyrazophos were found to be toxic at the dosages used. Results are compared to results obtained with other species of beneficial arthropods in the laboratory. The importance of including several species in the assessment of pesticide side effects as well as the importance of measuring sublethal effects are stressed.

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Résumé Des expériences de laboratoire ont été faites pour étudier les effets de 37 fongicides (dont plusieurs étaient des mélanges) sur les femelles adultes d'Aleochara bilineata. Les pesticides ont été testés à des concentrations équivalant aux plus fortes doses recommandées pour l'usage agricole. La mortalité, la production et l'éclosion des œufs ont été étudiées. La plupart des fongicides n'ont pas d'effet important sur aucun des paramètres retenus. Parmi les fongicides à base de morpholine et de dithiocarbamate, plusieurs avaient un effet contraire sur la production et l'éclosion des œufs. En outre le chinométhionate et le pyrazophos se sont révélés toxiques aux doses utilisées. Les résultats ont été comparés à d'autres résultats obtenus avec d'autres espèces d'auxiliaires au laboratoire. L'importance d'inclure plusieurs espèces dans l'évaluation des effects secondaires des pestieides ainsi que l'importance de mesurer les effets sublétaux sont soulignées.