A differential basis of antifungal activity of acylalanine fungicides and structurally related chloroacetanilide herbicides in Phytophthora megasperma f. sp. medicaginis

The acylalanine fungicides CGA 29212 and metalaxyl inhibit colony growth of Phytophthora megasperma f. sp. medicaginis at much lower concentrations than structurally related chloroacetanilide herbicides. Metolachlor, among the latter, shows the highest antifungal activity, followed by propachlor. Dimethachlor and alachlor are only weakly inhibitory. A metalaxyl- and CGA 29212-resistant strain of P. megasperma f. sp. medicaginis shows cross-resistance to metolachlor and propachlor, but levels of resistance are much lower than observed with CGA 29212 and metalaxyl. Cross-resistance does not occur to dimethachlor and alachlor. All compounds except metalaxyl inhibit uptake of [³H]uridine by mycelium, propachlor being most effective. Effects are similar with both a metalaxyl-sensitive and a -resistant strain. CGA 29212, metalaxyl, and metolachlor inhibit incorporation of [³H]uridine into RNA by mycelium of the sensitive strain at concentrations not inhibitory to uptake. Metalaxyl slightly affects incorporation by mycelium of the resistant strain; the other compounds have a more pronounced effect but only at concentrations inhibitory to uptake. Metalaxyl, CGA 29212, and propachlor do not induce leakage of radioactivity from mycelium of both strains when added at high concentrations to cultures previously incubated with [³H]uridine; under these conditions incorporation by mycelium of the metalaxyl-resistant strain is significantly more affected by CGA 29212 and propachlor than by metalaxyl. Endogenous RNA polymerase activity of isolated nuclei from a metalaxyl-sensitive strain is inhibited by CGA 29212, metalaxyl, and metolachlor but not by propachlor, dimethachlor, and alachlor. Neither compound has any effect on endogenous RNA polymerase activity of isolated nuclei from a metalaxyl-resistant strain. CGA 29212 and metolachlor evidently have a metalaxyl-type of action. The presence of cross-resistance of the metalaxyl-resistant strain to propachlor also indicates a metalaxyl-type of action for this compound, although this could not be confirmed by an inhibitory effect of propachlor on endogenous RNA polymerase activity. In addition to a metalaxyl-type of action, CGA 29212, metolachlor, and propachlor have a second one that is also present in dimethachlor and alachlor, which lack the metalaxyl-type of action. The second mechanism of action, involving inhibition of [³H]uridine uptake, is most prominent with propachlor and might be related to the primary mechanism of action in plants of the chloroacetanilide herbicides.     

Mode of action of the systemic fungicides furalaxyl,metalaxyl and ofurace

The systemic fungicides furalaxyl, metalaxyl and ofurace,

1 Ofurace is the proposed BSI and ISO common name for α-(2-chloro-N-2,6-xylylacetamido)-γ-butyrolactone.

used to control diseases caused by phycomycetes, were extremely active in vitro against Pythium ultimum, Phytophthora nicotianae and Phytophthora palmivora. Sporangia production was reduced more than mycelial growth but germination of sporangia and zoospores was relatively unaffected. Less than 1% of the metalaxyl or furalaxyl, present in media at the ED₅₀ for hyphal growth, was firmly absorbed by Phyt. palmivora mycelium; uptake was against a concentration gradient and was characterised by a rapid accumulation followed by a more gradual release. Respiration and wall synthesis were not inhibited, whilst membrane permeability was unaffected. Lipid patterns were altered but these changes were probably of secondary importance. The fungicides inhibited protein and nucleic acid synthesis; RNA production was particularly affected. There was some evidence of a reduction in nuclear division. The primary effect of furalaxyl and metalaxyl probably involves impaired biosynthesis of RNA so that mitosis is inhibited; ofurace may act in the same way.     

An ultrastructural study of the effect of metalaxyl on Phytophthora capsici infected stems of Capsicum annuum

Stems of pepper seedlings were inoculated with zoospores of Phytophthora capsici 18 h after a soil-drench with metalaxyl solution (5 μg ml^?1) or water. Infected stem tissues were examined by electron microscopy 24 h after inoculation. Compared with untreated controls, in which the fungal cells were generally normal in shape and ultrastructure, the most conspicuous effects of metalaxyl treatment on the fungal ultrastructure in the stem tissue were an abnormal shrinking of the fungal cell, a separation of the plasma membrane from the hyphal wall, a peculiar invagination and breakdown of the plasma membrane, the presence of vesicles in the invaginated spaces and within the damaged fungal cells, and an indistinct structure of cell organelles. In metalaxyl-treated stems, an electron-dense material was apposed in those sites of the host cell wall in most intimate contact with the fungal cell wall, indicating that the deposition of these substances from the host cell walls may function as a plant defence reaction to the fungus, whereas in untreated controls, the dark-stained host cytoplasm did not aggregate around the sites of fungal contact. The haustorium was encased by the extra-haustorial matrix in treated stems. These results suggest that metalaxyl treatment not only changes the fine structure of P. capsici, but may also induce the plant defence reaction.     

防治大豆疫霉根腐病的药剂筛选

在离体条件下测定了 8种内吸性杀菌剂对大豆疫霉菌菌丝生长的抑制作用。甲霜灵、甲霜灵锰锌、安克锰锌、杀毒矾、霜脲锰锌、克露和加瑞农为有效杀菌剂 ,霜霉威不具有抑菌效果。甲霜灵的 EC50 值为0 .4 870 μg/ m L,抑菌效果最好 ,安克锰锌、甲霜灵锰锌的 EC50 值分别为 1.4 2 6 1μg/ m L和 1.76 97μg/ m L,效果次之。在活体条件下 ,甲霜灵和甲霜灵锰锌能完全抑制大豆疫霉菌对感病大豆品种的侵入 ,并具有较长的药效期 ,安克锰锌、杀毒矾和霜霉威虽然具有明显的防治效果但药效期很短。大豆疫霉菌菌株间对甲霜灵锰锌的敏感性存在差异 ,但这种差异与菌株来源没有相关性 ,EC50 平均值为 1.830 2μg/ m L ,没有发现耐药性菌株。在我国黑龙江省目前缺乏有效抗病品种的情况下 ,建议应用甲霜灵锰锌防治大豆疫霉根腐病。     

The vacuoles containing multivesicular bodies: a new observation in interaction between Ustilago esculenta and Zizania latifolia

Ustilago esculenta infects Zizania latifolia plants and induces swelling on their upper culms. As an edible aquatic vegetable, these swellings are called jiaobai (white bamboo). The process of fungal development in Huijiao (grey bamboo) plants from seedlings to upper culm swelling was investigated using knife cut tissues, light and electron microscopy. All Huijiao plants were relatively taller than all jiaobai plants and in knife-cut sections sori development differed after culm swelling in Huijiao plants. Light microscope examination show that hyphae were both intracellular and intercellular, forming hyphal aggregations, and were more abundant in nodes than in internodes. Rapid increase of hyphal aggregations occurred 15 days before culm swelling, causing the death of abundant host cells, and hyphal aggregations differentiated into sori initiates. Ultrastructural observation showed that intracellular hyphae at the interface of fungus-host interaction were encased in a sheath with outer electron-opaque and inner electron-dense layer. Scale-like material and membrane-bounded vesicles were often present in an outer electron-opaque matrix of the sheath. Vacuoles, lipid globules (LGs) and multivesicular bodies (MVBs) were occasionally seen in these fungal cells. In summer, abundant electron-dense MVBs, LGs and fewer vacuoles containing MVBs were present in a fungal cell. As the temperature decreased, some MVBs became electron-opaque, some internal vesicles were also electron-opaque, and subsequently, the MVBs disappeared, leaving irregular remnant materials in vacuoles. During the rapid increase in hyphal aggregations, the irregular remnants of material within the vacuoles disappeared and LGs were rare. At the beginning of sori development, LGs once again became abundant in the cells of hyphal aggregation. The process of sorus and teliospore development was observed systematically and relationships between each developmental stage examined from knife cut tissues, and cytological and ultrastructural sections. Sorus development occurred with the commencement of upper culm swelling and differed in the same tissues. Teliospore development was also uneven in a sorus. The inner region of a sorus developed earlier than the outer part.     

Metalaxyl-induced changes in the antioxidant metabolism of Solanum nigrum L. suspension cells

The antioxidant responses of Solanum nigrum L. cell suspension cultures to metalaxyl exposure were investigated. An increase in lipid peroxidation and hydrogen peroxide content, for both concentrations tested (20 mg L⁻¹; 40 mg L⁻¹) revealed the response of oxidative metabolism of cell suspensions to metalaxyl. Superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6) and ascorbate peroxidase (APX; EC 1.11.1.11) activities increased, particularly in the highest concentration of metalaxyl used. An analysis by non-denaturing polyacrylamide gel (PAGE) followed by staining for enzyme activity, revealed seven SOD isoenzymes, two CAT isoenzymes, and nine APX isoenzymes. Metalaxyl levels were quantified in the culture medium and results suggest that suspension cells were able to accumulate and/or degrade the fungicide five hours after exposure. SOD, CAT and APX isoenzymes were differently affected by the metalaxyl treatment. Results suggest that the higher concentration of metalaxyl induced oxidative stress to cell suspension cultures of S. nigrum.     

On a difference in the antifungal activity of tridemorph and its formulated product Calixin

The antifungal effects of tridemorph and its formulated product Calixin were compared in vitro on Ustilago maydis, Saccharomyces cerevisiae, Torulopsis candida, Botrytis allii, and Cladosporium cucumerinum. MIC values for both products were about the same. In liquid media the products were somewhat more effective than on solid media. T. candida proved sensitive only at pH 5, but the other organisms were as sensitive at pH 7 as at pH 5. Whereas tridemorph even at high concentrations did not affect oxygen consumption of these organisms, Calixin at concentrations slightly above the MIC values appeared to inhibit respiration. This effect of Calixin could be explained by the presence of Nekanil LN in the formulation. This compound inhibited both growth and respiration of the organisms at high concentrations; however, in the simultaneous presence of tridemorph a synergistic effect on oxygen consumption was observed.     

Species of Pythium in the Netherlands

A review is given on observations ofPythium spp. so far published. In personal investigations about 4000 isolates ofPythium species were obtained from soil, water, Daphnias and plants during 1966–1972. Special attention was paid to the progressive colonization of the newly reclaimed polder Zuidelijk Flevoland: the numbers of species per sample increased from 0 in 1966 to 13 in 1972. The percentage of samples which did not contain anyPythium decreased from 54 in 1968 to 0 in 1972. From Zuidelijk Flevoland altogether 21 species were isolated, from Oostelijk Flevoland 22, of which 19 occurred in both the polders. The soil depth down to 10 cm had little influence on the occurrence ofPythium species. From soils near Rhenen and Zutphen 12 and 19 species respectively were isolated, from flax and flaxfields 11, from forests 8, from roots of different plants 17 and from water 11. Besides species already previously recorded, 15 new records ofPythium species for the Netherlands are documented. Species with filamentous non-swollen sporangia preferentially occurred in water and wet soils while species with spherical sporangia or hyphal swellings dominated in cultivated soils, forests and in the roots of phanerogams. In 1968 species with filamentous non-swollen sporangia comprised 89% of the isolations from Zuidelijk Flevoland; this percentage decreased to 9 in 1972. The percentage of isolates with spherical sporangia or hyphal swellings from cultivated soils, forest soils or plant material was mostly over 90.P. rostratum Butler, though found in all kinds of soils, was often the only species which could be isolated from dry sandy soil samples.P. sylvaticum Campbell & Hendrix was the most common species in cultivated soils in the Netherlands (37% of the isolates in 1968–1972), followed byP. oligandrum Drechsler (22%) andP. paroecandrum Drechsler (11.5%).     

Enantioselective degradation kinetics of metalaxyl in rabbits

Metalaxyl [methyl-N-(2′-methoxyacetyl)-N-(2,6-dimethylphenyl)-d,l- alaninate] is a potent phenylamide fungicide. The (−)-(R)-isomer accounts for most of the fungicidal activity. A possible stereo and/or enantioselective kinetics of metalaxyl in rabbits was investigated by intravenous injection. The concentrations of (−)-(R)- and (+)-(S)-metalaxyl in plasma, liver, and kidney tissue were determined by HPLC with a cellulose-Tris-(3,5-dimethylphenylcarbamate)-based chiral stationary phase and gas chromatography-mass spectroscopy. After intravenous administration of racemic metalaxyl (40 mg/kg), the (+)-(S)-enantiomer levels in plasma, liver, and kidney decreased more rapidly than the (−)-(R)-isomer. The area ratio of the (−)-(R)-/(+)-(S)-enantiomer under the concentration-time curve (AUC_0 → ∞) in plasma after drug application was 1.62. The total plasma clearance value of the (+)-(S)-enantiomer was 1.53 and higher than that of the (−)-(R)-enantiomer. The [R]/[S] ratio in plasma was >1 for standard rac-metalaxyl at each time point. The other pharmacokinetic parameters of the enantiomers were also different. The results indicate substantial stereoselectivity in the degradation of metalaxyl enantiomers in rabbits.     

Effect of fungicides on stages of the life cycle of Phytophthora cinnamomi

An assessment was made of the effects of several fungicides on the formation of zoosporangia, the release of zoospores from zoosporangia, zoospore motility, germ tube formation and mycelial growth, by Phytophthora cinnamomi Rands. Compounds active against mycelial growth (such as metalaxyl and furalaxyl), as well as those active against zoospores (such as captafol and zineb), could be detected by a lupin (Lupinus angustifolius L.) assay which has been developed. This assay may be useful as a screening procedure to detect new fungicides.     

Studies on the systemicity of [14C]metalaxyl in cowpea (vigna unguiculata (L.) walp.)

[¹⁴C]metalaxyl applied to seeds, roots and leaves of cowpea was readily taken up by all plant parts and a major fraction of it was retained within the treated leaves and seeds but not in the roots. The fungicide exhibited ambimobility inside the plant. When applied to the middle of leaflets, metalaxyl mobilised towards proximal and distal parts of the leaflet. Intraleaflet movement seemed to result from translocation through veins and diffusion through cell walls and intercellular spaces. Accumulation of metalaxyl at tips and margins of primary leaves followed application to roots. Metalaxyl was readily extracted from most plant parts except cotyledons and only 0.8% of the fungicide applied as a seed treatment was recovered from 50-day-old plants.     

Resistance to metalaxyl in isolates of the sunflower pathogen Plasmopara halstedii

Plasmopara halstedii isolates showing an atypical reaction to metalaxyl were collected in France, in 1995 and 1996, and tested in the laboratory for their level of sensitivity to this fungicide. Primary and secondary infections caused by one of these isolates were not controlled by the metalaxyl concentration registered for seed treatment. The EC₅₀ of this isolate was 12 800 mg a.i. kg^-1 compared with 22 mg a.i. kg^-1 for sensitive isolate, indicating a 582-fold decrease in sensitivity to the compound. There was no reduction in the agressiveness of the resistant isolate. Using other anti-oomycete fungicides, it appeared that propamocarb, contact fungicides (fluazinam, folpet, mancozeb) and the mixed formulations dimethomorph + mancozeb, cymoxanil + mancozeb and ofurace + folpet were effective against primary infections made with metalaxyl resistant and sensitive isolates, but not against secondary infections. Metalaxyl mixed with fluazinam, folpet or mancozeb was more effective against primary infections with the resistant isolate than metalaxyl alone. The EC₅₀ of five other isolates ranged from 5 800 to 32 900 mg a.i. kg^-1, indicating a variability in metalaxyl sensitivity of resistant sunflower downy mildew isolates. This is the first report of physiological resistance to metalaxyl in Plasmopara halstedii.     

Synergistic interactions between phenylamide fungicides and respiration inhibitors in controlling phenylamide-resistant populations ofPhytophthora infestans on potato tuber disks

The efficacy of mixtures of respiration inhibitors and phenylamide fungicides (oxadixyl and metalaxyl) in controlling late blight was investigated using potato tuber disks. Results showed that uncoupling agents(e.g. DNP), inhibitors of ATP formation(e.g. oligomycin), ionophores(e.g, valinomycin) and inhibitors that block specific carriers in the electron transport chain(e.g. rotenone, antimycin A) increased significantly the control efficacy of both metalaxyl and oxadixyl towards populations ofPhytophthora infestons when applied to tuber slices pretreated with sublethal doses of both fungicides. When applied alone at the same doses, respiration inhibitors did not inhibit the development of the late blight fungus. Increased control efficacy of mixtures was not noted against phenylamide-sensitive populations of the fungus.     

Preliminary evaluation of nine fungicides for control ofPhytophthora cactorum andP. citrophthora associated with crown rot in peach trees

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.     

Reduced persistence of metalaxyl in soil associated with its failure to control cavity spot of carrots

Metalaxyl was used to control Pythium diseases of carrots in experiments on farms with a history of cavity spot. The first experiment compared the method of application (sprayed, banded or broadcast) and rate (0, 1.5, 3 or 6 kg a.i. ha⁻¹) one week after sowing. Three additional experiments compared the rate (0, 0.75, 1.5 or 3 kg a.i. ha⁻¹) and time (sowing, 1- to 2- or 4- to 5-true-leaf stage) of application. In expt 1, the application of metalaxyl, but not the method by which it was applied, increased yield by 20% and significantly reduced the incidence of cavity spot, forking and misshapen carrots. In expts 2, 3 and 4, neither the rate nor time of application affected yield or reduced the incidence of Pythium diseases. Comparison of the sites showed that they differed in past metalaxyl usage. Metalaxyl had not been used on the site of expt 1, but had been used previously at sites 2, 3 and 4. Laboratory experiments were conducted to determine whether these differences in efficacy resulted from reduced sensitivity of Pythium isolates to metalaxyl, or reduced persistence of metalaxyl in soil. ED₅₀ values showed that there was no reduction in metalaxyl sensitivity. The half-life of metalaxyl was 82 days in soil from expt 1, but was 10 days or fewer in soils from expts 2, 3 and 4. Thus the failure of metalaxyl to control Pythium diseases was associated with reduced persistence in soil, not reduced sensitivity of the target fungi.     

Occurrence of metalaxyl-resistant isolates of Pseudoperonospora cubensis in Israel: a 5-year survey1

The occurrence of metalaxyl-resistant isolates of Pseudoperonospora cubensis, the causal agent of downy mildew in cucurbits, was surveyed during 1980–1984 subsequent to their first appearance in December 1979. Metalaxyl use was abandoned in mid-1981 and resistant isolates diminished in late 1981. Metalaxyl use was renewed in 1982 and a gradual increase in frequency of resistant (R) strains was detected. In 1983, 31 out of 40, and in 1984, 43 out of 47 isolates tested were highly resistant to the fungicide with 65 and 91% of them, respectively, collected from plastic houses or fields not treated with metalaxyl. The survey indicates a rapid build-up of R strains of the fungus and the need for alternative chemicals for combating downy mildew in cucurbits.     

昆明桃园梨小食心虫发生规律

2011-2013年对昆明桃园梨小食心虫发生规律及为害特点进行了系统调查研究。结果表明:3年来昆明地区梨小食心虫发生趋势基本一致,但各年度发生的大高峰期有差异,2012年成虫发生大高峰期为越冬代、第一代;2013年成虫发生大高峰期在第二、三代,这与当时的温度、降水量有很大关系。昆明梨小食心虫一年发生4代,越冬代成虫发生高峰期在3月中旬至4月上旬,第一代发生高峰期在5月上旬至6月中旬,越冬代、第一代主要为害桃树新梢,新植桃园幼虫更趋向在低龄桃树为害,幼虫蛀梢的高峰期在成虫羽化高峰期后15~30d;第二、三代发生高峰期在7月上旬至9月下旬,世代重叠明显,后两代主要为害果实。经饲养观察,桃园梨小食心虫性比[♀/(♀+♂)]为0.57~0.64,幼虫被天敌寄生率为26.9%,幼虫蛀果率为1.25%~5%。     

马铃薯晚疫病菌对甲霜灵抗性机制的初步研究

 选取对甲霜灵敏感、中抗和高抗的马铃薯晚疫病菌(Phytophthora infestans)菌株各2株,采用电导率法和同位素掺入法,研究了甲霜灵对马铃薯晚疫病菌不同抗药性水平菌株细胞膜通透性和RNA聚合酶活性的影响,借助液相色谱分析方法检测了不同抗药性水平菌株对甲霜灵的降解作用。结果表明:甲霜灵对马铃薯晚疫病菌不同抗药性水平菌株的细胞膜通透性没有明显影响;随着甲霜灵浓度提高,敏感菌株的RNA聚合酶活性受到显著抑制,10μg/mL甲霜灵对敏感菌株RNA聚合酶活性的抑制率达到40%以上,而10和100μg/mL甲霜灵对高抗菌株的RNA聚合酶活性只表现轻微的抑制作用,抑制作用分别小于8%和21%,甲霜灵对中抗菌株RNA聚合酶活性的抑制作用介于对敏感菌株和高抗菌株的抑制作用之间。抗性菌株对甲霜灵有一定的降解作用,培养30d后高抗菌株HL105和SC1的降解率分别达到13.46%和16.14%。     

Regression Analyses for Evaluating the Influence of Bacillus cereus on Alfalfa Yield Under Variable Disease Intensity

ABSTRACT We developed and tested regression methods to exploit the variability in disease inherent in field experiments, and applied the methods to evaluate strains of Bacillus cereus for biocontrol efficacy. Four B. cereus strains were tested for their effect on alfalfa (Medicago sativa) performance in 16 field trials planted during 1993 to 1996 at multiple sites in Wisconsin. To evaluate performance of the strains, we used the ratio of (metalaxyl response)/(untreated control response) as a measure of disease intensity within the experiments. The ratio of (Bacillus response)/(untreated control response) was then regressed as a function of disease intensity. The slope of the resulting line provides a statistical test to compare performance of the Bacillus strain with that of the untreated seed (H(o): slope = 0) and metalaxyl controls (H(o): slope = 1). Under conditions in which disease occurred, forage yield of plots planted with seed treated with B. cereus strain AS4-12 exceeded yield from the untreated control plots (P = 0.002) and was similar to yield of plots planted with metalaxyl-treated seed (P = 0.14). Yield gain associated with AS4-12 and metalaxyl seed treatment averaged 6.1 +/- 2.8% (+/-standard error) and 3.0 +/- 2.8%, respectively. In contrast to the regression approach, means analysis by analysis of variance did not detect differences among treatments. Three other B. cereus strains either did not increase alfalfa yield or increased yield less than did AS4-12. Metalaxyl and three of the Bacillus strains increased seedling emergence, but the improved stands were not predictive of increased forage yield. In six additional studies conducted for one season in 1997, AS4-12 enhanced yield of two cultivars at diverse locations in Wisconsin, but there was an apparent cultivar-location interaction. A strong correlation between response to AS4-12 and metalaxyl treatment suggests that these treatments controlled similar pathogens, most likely the oomycete pathogens Phytophthora medicaginis and Pythium spp.     

“霜霉威(Propamocarb)”“甲霜灵(Metalaxyl)”对我国辣椒疫霉菌作用方式比较及交互抗性的研究

 通过霜霉威(Propamocarb商品名普力克)、甲霜灵(Metalaxyl商品名瑞毒霉)对辣椒疫霉菌(Phytophthora capsici)6个菌株作用方式的体外测定结果表明,霜霉威浓度在2000ppm时对P. capsici孢子囊和卵孢子的形成,游动孢子的释放、游动及休止孢萌发、菌丝体的生长没有明显的抑制作用。而甲霜灵对P. capsici的各种孢子的产生及菌丝体的生长有较强的抑制作用,对菌丝体生长抑制的Ec₅₀和Ec₉₅分别为0.5596ppm和2.1511ppm;对孢子囊形成抑制的Ec₅₀和Ec₉₅分别为0.1520ppm和15.0032ppm。0.1ppm的甲霜灵可显著抑制卵孢子的生成。但500ppm的甲霜灵对于游动孢子的释放和休止孢萌发没有明显的抑制作用。对霜霉威和甲霜灵的体内活性试验结果表明,800ppm的霜霉威对辣椒疫霉菌的内吸保护防效达94%,1.0ppm的甲霜灵对该病的防效达100%。室内初步试验结果表明,甲霜灵与霜霉威对P. capsici没有交互抗性。