共查询到20条相似文献，搜索用时 31 毫秒
1.
A. J. Dik N. J. Fokkema J. A. Van Pelt 《European journal of plant pathology / European Foundation for Plant Pathology》1991,97(4):209-232
Aphid honeydew on wheat leaves can affect host physiology directly and can stimulate infection by necrotrophic pathogens. The role of naturally occurring saprophytes on wheat flag leaves in removing aphid honeydew was examined in five field experiments at different locations in the Netherlands in 1987 and 1988. Aphid populations, saprophyte populations and aphid honeydew were measured weekly. Diseases were monitored at 1–4 week intervals.In the control treatment, sprayed with water, the naturally occurring saprophytes consumed the honeydew almost completely, except in one experiment in which the aphid population increased very rapidly. In the treatments in which the saprophytes were reduced by the broad-spectrum fungicide maneb in 1987 and with maneb alternated with anilazin in 1988, honeydew accumulated. The observed honeydew consumption by the naturally occurring saprophytic population is ascribed mainly to pink and white yeasts (Sporobolomyces spp. andCryptococcus spp., respectively).Additional treatments showed, that in the presence of the naturally occurring saprophytes the yield loss per aphid-infestation-day was lower than when the saprophytes were inhibited by fungicides, showing that yeasts can reduce the detrimental effect of aphid honeydew in wheat. 相似文献
2.
The sensitivity to fungicides of saprophytic fungi colonizing cereal leaves (mainly ←pink→ yeasts, Sporobolomyces spp.; ← white → yeasts, Cryptococcus spp.; Aureobasidium pullulans and Cladosporium spp.) is discussed. Fungicides like dithiocarbamates, captafol, benzimidazoles and tridemorph reduce the saprophytic microflora, while others have little or no effect. The fungicides are mostly effective for 2–3 weeks after the treatment. When evaluating the consequences of a disturbance of the microbial balance we should realize that the saprophytes are able to antagonize a number of necrotrophic pathogens of cereal leaves and ears (Cochliobolus sativus, Septoria nodorum, Fusarium culmorum, Pseudocercosporella herpotrichoides, Colletotrichum graminicola). This antagonism is based on nutrient competition, which reduces the superficial development of the pathogen before penetration, resulting in a reduction of infection of about 50 % or more. This interaction seems particularly important when saprophytes compete successfully for extraneous nutrients from pollen grains or aphid honeydew, which will otherwise stimulate infection. 相似文献
3.
R. Rabbinge A. Brouwer N. J. Fokkema J. Sinke T. J. Stomph 《European journal of plant pathology / European Foundation for Plant Pathology》1984,90(5):181-197
The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi. 相似文献
4.
The effect of nutrients on reduction of the germination and mycelial growth of Septoria nodorum by the fungicides propiconazole, fenpropimorph and prochloraz, and on the reduction of S. nodorum infection by prochloraz, was tested on wheat plants in a controlled environment. The nutrients tested were aphid honeydew, sucrose, a mixture of amino acids and combinations of sucrose with yeast extract and amino acids, all in different concentrations. All nutrients could stimulate S. nodorum infection in combination with the tested prochloraz concentrations (4.5–45 mg a.i./1), but amino acids did not significantly stimulate infection in the fungicide-free treatments. The stimulating effect of the nutrients was generally stronger with higher nutrient/fungicide ratios. Aphid honeydew had more effect than its main components sucrose and amino acids separately. Antagonism between nutrients and prochloraz was determined with the Colby method and from dose-response curves by comparing ED50 S and drawing antagonism isoboles. Aphid honeydew, sucrose and amino acids caused an up to 10-fold increase of the ED50 and can be considered antagonistic to prochloraz. 相似文献
5.
Colin H. Dickinson 《Pest management science》1973,4(4):563-574
Phylloplane micro-organisms may metabolise substances present on the leaf surface, they may interact with leaf pathogens and they may be involved in the process of senescence. The effects of fungicides on many leaf saprophytes are, however, largely unknown. Studies under both field and laboratory conditions have indicated that wide spectrum protectant fungicides, such as captan, captafol and zineb, are as effective against the saprophytic flora as they are against plant pathogens. If the leaf surface microflora is restricted by fungicides then antagonism towards pathogens will also be reduced, but beneficial results may ensue if the microbial impact on senescence is lessened. Field trials with barley have demonstrated that it is possible to delay senescence by using fungicide sprays. 相似文献
6.
4种戊烷脒同系物对灰霉病的防治效果 总被引：2，自引：2，他引：2
采用载玻片萌发法、抑制菌丝生长速率法、组织测定法，结合田间小区试验，系统研究了戊烷脒及其同系物乙烷脒、丙烷脒、丁烷脒对番茄灰霉病菌的抑制活性和田间防治效果。结果表明，各化舍物对灰霉病均有一定的抑制活性，其中丙烷脒和丁烷脒对灰霉病的抑制活性较高，二者抑制菌丝生长的EC50分别为0．6821mg／L和2．1599mg／L，抑制孢子萌发的EC50分别为2．7510mg／L和5．7362mg／L；丙烷脒和丁烷脒对番茄灰霉病有较高的保护和治疗作用；在田问试验条件下，连续2次施药后，以120g ai／hm^2施用剂量防治豇豆灰霉病，丙烷脒和丁烷脒的防治效果分别为78．03％和54．52％，以100gai／hm^2施用剂量防治草莓灰霉病，防治效果分别为71．97％和68．96％，均优于对照药剂施佳乐（450gai／hm^2）和速克灵（468．8gai／hm^2）。丙烷脒和丁烷脒具有开发成为农用杀菌荆的潜力。 相似文献
7.
The synergistic effect of a range of ergosterol-biosynthesis-inhibiting (EBI) fungicides and a pyrethroid insecticide was studied in the honeybee (Apis mellifera L.). Various EBI fungicides were combined separately with the pyrethroid lambda-cyhalothrin at ratios derived from their recommended application rates to represent tank-mixing in the field. The mixture was then applied topically to the thorax of honeybees, and mortality assessed 24 h post-treatment. All the fungicides tested increased the toxicity of lambda-cyhalothrin to honeybees. The fungicide propiconazole was found to have the strongest synergistic effect, decreasing the LD50 of lambda-cyalothrin from 68.0 ng bee?1 to 4.2 ng, thus having a synergistic ratio of 16.2. Hazard ratios were calculated for lambda-cyhalothrin and fungicide mixtures using a recommended application rate of 7.5 g a.i. ha?1. The hazard ratio for lambda-cyhalothrin alone was 110, but when mixed with fungicide synergists, the hazard ratio ranged from 366 with flutriafol to 1786 with propiconazole. A blank formulation of a fungicide (without the active ingredient prochloraz) had little effect on the toxicity of lambda-cyhalothrin, indicating that it is primarily the fungicide active ingredient that is responsible for the synergistic effect. The results are discussed in terms of the potential hazard posed by pesticide synergism to honeybees in the field. 相似文献
8.
Chemical control of plant diseases 总被引：2，自引：0，他引：2
As the world population increases, we also need to increase food production. Chemical control has been critical in preventing losses due to plant diseases, especially with the development of numerous specific-action fungicides since the 1960s. In Japan, a host-defense inducer has been used to control rice blast since the 1970s without any problems with resistance development in the pathogen. Leaf blast has been controlled using a labor-saving method such as the one-shot application of a granular mixture of fungicide and insecticide to nursery boxes, which became mainstream in the 2000s. However, the need for many choices of fungicides that have several modes of action was demonstrated by the development of resistance to cytalone dehydratase inhibitors. In Europe, many pathogens have threatened cereals since the great increase in cereal production in 1970s, creating a large market for broad-spectrum fungicides. In Brazil, Phakopsora pachyrhizi was distributed to large soybean acreages during 2000s, and the outbreak of soybean rust resulted in a large increase in fungicide use. While the importance of chemical control is recognized, fungicide resistance is an avoidable problem; published guidelines on countermeasure and manuals on testing sensitivity to fungicides are available. Since chemical regulations have become stricter, new fungicides are less likely to be developed. Our task is to maintain the effectiveness and diversity of the present modes of action for fungicides and implement countermeasures against the development of fungicide resistance. 相似文献
9.
Dhruv Aditya Srivastava Mariana Yakubov Reut Feldbaum Nimrod Tish Hagit Shoyhet Ekaterina Manasherova Eswari P. J. Pandaranayaka Dalia Rav-David Yigal Elad Arye Harel 《Phytoparasitica》2018,46(4):569-581
The necrotrophic fungus Botrytis cinerea, known as the causal agent of gray mold, is ranked second for its phytopathological global-impact. The disease is controlled by cultural means and fungicides, however, these techniques have variable effect on different fungal isolates due to the plasticity of the pathogen populations. Here we studied and characterized the genetic and virulence associated variability of B. cinerea isolates from different sources. Starting from initial survey of 31 B. cinerea isolates, collected from seven hosts in different locations of Israel, we have focused on 10 isolates that exhibited potential phytopathogenic variability. Two genetic markers (microsatellite) Bc1 and Bc7, were able to differentiate between these isolates. Our analysis demonstrates significant variability in saprophytic growth rate, necrotrophic growth rate on tomato leaves and stems, and in the incidence of infection on leaves of whole plants. Following the observation of significant correlation between saprophytic growth rate, and necrotrophic growth on leaves, we have studied normalized (by saprophytic growth) virulence. Utilization of normalized necrotrophic growth rate enabled to indicate on the presence of virulence mechanisms other than growth rate, for several isolates. Exploration of this direction illustrated variability in resistance to paraquat (associated with resistance to oxidation), which was associated with high and low superoxide dismutase (SOD) gene expression for selected isolates showing high or low paraquat resistance, respectively. Finally, we have used unsupervised learning (clustering analysis) to explore patterns in the multivariable space, which demonstrated two modes of pathogenicity in the tested B. cinerea isolates. 相似文献
10.
D. C. Griffiths K. A. Jeffs G. C. Scott R. Gair E. Lester F. E. Maskell J. H. Williams 《Pest management science》1972,3(5):609-618
When seeds of winter wheat were carefully dressed in the laboratory with combinations of fungicides (organomercury alone or organomercury plus the systemic fungicide carboxin) and insecticides (aldrin, carbophenothion or chlorfenvinphos as liquid formulations, or a γ-BHC powder formulation) so as to ensure that nearly all the recommended amounts of the active ingredients stuck to them, the insecticides gave good insect control, but γ-BHC with organomercury fungicide decreased the number of plants that germinated, and γ-BHC with carboxin and organomercury was even more damaging. Commercially dressed seeds had only about 30 to 60% of the target dose of fungicides, but more than 80% of the target doses of the liquid insecticides aldrin, carbophenothion and chlorfenvinphos. With combinations of powder fungicide and liquid insecticide, greater amounts of pesticide on the seed were obtained if the insecticide was put on first. Because of unusually late sowings and little fungal infestation, neither laboratory nor commercially treated seeds provided good tests for control of smut. 相似文献
11.
Dolar Pak Ming Pei You Vincent Lanoiselet Martin J. Barbetti 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(2):247-259
Fungicides are the preferred rice blast (Pyricularia oryzae) control option by farmers. However, no fungicides are yet registered for this purpose in Australia. Hence, it is important to test the baseline sensitivity of P. oryzae isolates collected from blast-affected regions across northern Australia, which have not yet been exposed to the fungicides, as part of a resistance management strategy. Further, it is also important to investigate and compare effect of application timing of fungicides on conidial development, including germination and germ tube growth, and penetration on susceptible rice. The EC50 of a collection of fungicide-sensitive blast isolates were within the range of 0.02–2.02 and 0.06–1.91 mg L?1 for azoxystrobin and propiconazole, respectively. Azoxystrobin was shown to have greater inhibitory effect on conidial germination than propiconazole. In addition, for pre-inoculation application, only germ tubes in the presence of external nutrients continued to grow from 24 to 48 hpi. On susceptible seedlings, both fungicides completely controlled blast disease when applied the same day as inoculation. However, for pre- or post-inoculation application of fungicide, the extent of disease control was reduced, with azoxystrobin more efficacious than propiconazole. A stimulatory effect of both fungicides at low dose was observed on certain P. oryzae isolates. This is the first study to assess the baseline sensitivity of the P. oryzae population in Australia and the first to report a stimulatory effect of low azoxystrobin concentration on growth of P. oryzae. The study highlights, for the first time, the critical role of external nutrients in promoting germ tube growth under fungicide stress conditions. Lastly, it demonstrates the high degree of efficacy of the fungicides and their potential for future rice blast management in Australia. 相似文献
12.
It had been found earlier that the chloronicotinyl insecticide thiacloprid (as the 480 g litre(-1) SC Calypso) poses a favourably low toxicity hazard to the honeybee, Apis mellifera L. As with pyrethroids, the metabolization of chloronicotinyl compounds involves monooxygenases, which are known to be inhibited by some ergosterol biosynthesis inhibitor (EBI) fungicides potentially co-applied with these insecticides. The potential synergistic enhancement of the toxicity of thiacloprid to honeybees when co-applied with such fungicides was therefore studied under laboratory and semi-field conditions. Fungicides of other chemical classes were also examined for synergistic potential to reveal other metabolic interactions. In the laboratory, only a slight synergistic effect was observed with the anilinopyrimidine fungicide examined, while a significant enhancement of thiacloprid toxicity to honeybees was found with EBI fungicides. In three tunnel tests conducted under different environmental conditions to simulate field exposure, no increased mortality was observed when honeybees were directly sprayed with thiacloprid (Calypso) alone or in combination with the EBI fungicide tebuconazole (250 g litre(-1) EW, Folicur). There was also no synergized reduction in the foraging intensity on the treated crop. In general, the foraging intensity decreased after thiacloprid treatment but was restored within 24-48 h. The hive vitality was not affected by either thiacloprid or its tank mix with tebuconazole. Our results suggest that, at the recommended use rates, thiacloprid poses a negligible lethal risk to honeybees when applied either alone or in tank mixes with fungicides of various chemical classes. 相似文献
13.
Analysis of samples of seeds, mostly wheat, treated commercially with insecticides and fungicides showed that many carried much less than the theoretical dose, some less than one-tenth. The average loadings of seeds treated with dry powder formulations were nearly always small, but the distribution of insecticide between seeds was fairly uniform. The average loading of seeds treated with liquid formulations was closer to the target, but the distribution was irregular, most of the seeds carrying little insecticide and a few seeds amounts large enough to be phytotoxic. Insecticides applied as dry powders do not adhere strongly to the seeds, but they remain in association with seeds contained and carried in bags. Applied as liquids, insecticides are difficult to remove from seeds. The ratio of insecticide to fungicide on seeds dressed with powders containing both usually resembled the ratio in the original powder. With liquid seed dressings of insecticide and fungicide applied separately in different formulations, the ratio of insecticide to fungicide often differed widely from the theoretical. The average loading of fungicide was close to the target, but the average amount of insecticide was often much less. With either wet or dry dressings, the amount of pesticide on seeds was consistently greater from some merchants than from others. This was independent of the machinery used. Loadings were not consistently affected by type of seed-dressing machinery or formulation, stage of operation, weather or variety of seed. 相似文献
14.
15.
Abstract In field evaluation trials nine test fungicides significantly reduced the incidence and severity of leaf scald disease of rice caused by Monographella albescens (Thüm)(Rhynchosporium oryzae Hashioka & Yokogi) and increased the yield. Of these fungicides Difolatan (captafol) and Dithane M‐45 (mancozeb) were more effective than the other fungicides. Relatively longer persistence of fungicidal residues was detected in three test chemicals, i.e., Blitox‐50 (copper oxychloride), Difolatan and Dithane M‐45. Amount of rainfall appeared to be a main weather factor in influencing persistence of a fungicide. 相似文献
16.
Excised twig assay and excised stem inoculation were used to evaluate nine fungicides (metalaxyl, fosetyl-Al, copper hydroxide,
copper sulfate, copper oxychloride, captan, quintozene, propamocarb and chlorothalonil) againstPhytophthora cactorum andP. citrophthora associated with crown rot in peach trees. Segments were soaked in fungicide solutions at different concentrations and then
inserted vertically intoP. cactorum orP. citrophthora cultures growing on cornmeal agar plus antibiotics, or inoculated by inserting a mycelium-bearing agar plug directly into
the cambium. Following incubation, the bark was scraped off and length of necrosis was measured. Metalaxyl was the only fungicide
that inhibited canker development on segments at the manufacturer-recommended concentration. Fosetyl-Al, captan, copper hydroxide
and copper sulfate inhibited canker development at 3, 4, 4 and 8 gl-1, respectively. The other fungicides did not affect canker length significantly compared with non-treated twigs, with the
exception of propamocarb, which reduced the development ofP. cactorum on excised stems. The tested methods enabled rapid and effective evaluation of a large number of chemicals to prevent crown
rot diseases caused byPhytophthora in the laboratory.
http://www.phytoparasitica.org posting Dec. 5, 2001. 相似文献
17.
18.
为了筛选出防治苹果炭疽叶枯病的有效杀菌剂, 采用室外先接种后施药和先施药后接种的方法, 测试了6种药剂的内吸治疗效果和8种药剂的保护效果。在病菌侵染后的72 h内使用吡唑醚菌酯, 或在病菌侵染后的24 h内使用咪鲜胺对病斑的显症有一定的治疗效果。波尔多液在喷施后18 d, 对炭疽叶枯病菌侵染的抑制效果仍达50%, 肟菌?戊唑醇、烯酰?吡唑酯和唑醚?代森联3种药剂在施药后的第11天, 其保护效果与对照仍有显著差异, 持效期达11 d, 代森锰锌、甲基硫菌灵、氢氧化铜和咪鲜胺4种保护剂的持效期只能维持6 d。炭疽叶枯病的防治应以波尔多液为主, 并与吡唑醚菌酯等有机杀菌剂交替使用, 有机铜制剂不能替代波尔多液。 相似文献
19.
羧酸酰胺类(CAAs)杀菌剂研究进展 总被引：5，自引：3，他引：2
羧酸酰胺类(Carboxylic acid amides, CAAs) 化合物是一类对卵菌病害具有优异防治效果的新型杀菌剂。该类杀菌剂由3组化学结构各不相同的化合物组成,包括肉桂酰胺、缬氨酰胺氨基甲酸酯和扁桃酰胺类。由于这3类杀菌剂具有相似的杀菌活性且相互间存在正交互抗药性,国际杀菌剂抗药性行动委员会已于2005年底将这3类具有不同化学结构的杀菌剂归为羧酸酰胺类杀菌剂。对CAA类杀菌剂的化学结构特征、生物学活性、作用机制与抗药性的最新研究进展进行了综述。 相似文献
20.
为了筛选防治水稻旱育秧立枯病的有效药剂,通过秧盘试验和室内致病菌离体毒力测定,结合考察药剂对秧苗生长的影响,对保护性杀菌剂代森锰锌和福美双以及内吸治疗性杀菌剂稻瘟灵、 FDA1 霉灵等进行了系统评价。结果表明, FDA1 霉灵、甲基硫菌灵和稻瘟灵对致病菌离体毒力虽然不高,但由于 FDA1 霉灵和甲基硫菌灵对水稻秧苗生长均有促进作用,稻瘟灵能显著提高秧苗抗低温胁迫能力,这3种药剂对水稻立枯病的防治效果较好,防效达65%~81%;而离体毒力虽然高,但对秧苗生长不利的三唑酮、丙环唑和烯唑醇等三唑类药剂效果稍差,防效为51%~75%。根据试验结果提出稻瘟灵是防治该类病害的一种较理想的单用或混用药剂;针对水稻立枯病的发生受环境影响大、病原种类多等特点,指出在研究防治药剂时应采用活体筛选为主、离体筛选为辅的筛选方法,而且提倡不同杀菌谱品种的混用。 相似文献