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1.
Four field trials were conducted to evaluate the efficacy of various fungicide formulations in controlling late blight in
potato crops artificially inoculated with A2 metalaxyl-resistant isolates ofPhytophthora infestans. Two trials (Winter 1986, Spring 1987) were performed at the research farm of Bar-IIan University (central coastal
plain) and two trials (Winter 1987, Spring 1988) at the Besor Experiment Farm (western Negev), with seven formulations tested
in each trial. At Bar-IIan, Mancur (mancozeb + cymoxanil, 4:1) applied once a week was most effective in controlling the blight.
Sandocur-M and Pulsan (mancozeb + oxadixyl + cymoxanil, 7:1:2 and 7:1:0.4, respectively) applied at biweekly intervals were
the second best, while SAN 518F (mancozeb + oxadixyl, 7:1) and Ridomil-MZ (mancozeb + metalaxyl, 7.5:1) applied at biweekly
intervals, and mancozeb or cymoxanil applied once a week, were the least effective. At the Besor farm Ridomil-MZ at biweekly
intervals was the least effective, but the efficacy of the other formulations varied between the two trials. Mancur, Sandocur-M,
Previcur-N and mancozeb were highly effective in Winter 1987 but less so in Spring 1988. In the latter season Mancur, Sandocur-M
and Previcur-N were significantly more effective than mancozeb or Ridomil-MZ. The correlation coefficient between yield and
final disease level was -0.5322. 相似文献
2.
The efficacy of cymoxanil, Pulsan (oxadixyl + mancozeb + cymoxanil, 1:7:0.4) and Sandocur-M (oxadixyl + mancozeb + cymoxanil, 1:7:2) in controlling late blight was examined in potatoes (cv. ‘Alpha’). Nine oxadixyl-sensitive and seven oxadixyl-resistant isolates ofPhytophthora infestons from six countries were tested. ED90 values of cymoxanil ranged between 64 and 467 mg a.i./l. No relationship was observed between sensitivity to cymoxanil and sensitivity to oxadixyl. Isolate S6A (1305) from California was the most sensitive to cymoxanil (ED90 = 64 mg/l), whereas isolate R11 from Israel was the least sensitive (ED90 = 467 mg/l). Most isolates from Israel were less sensitive (ED90 = 151–467 mg/l) than isolates from Switzerland, the Netherlands, Ireland, Mexico or California (ED90 = 64–152 mg/l). Three-way mixtures of cymoxanil with mancozeb and oxadixyl were more inhibitory than cymoxanil alone, regardless of the isolate. Sandocur-M was, for most isolates, more effective than Pulsan. The correlation coefficient between sensitivity to cymoxanil and sensitivity to Sandocur-M was 0.67, while that between cymoxanil and Pulsan was 0.76. 相似文献
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The effect of oxadixyl-based fungicidal mixtures on the development of late blight and the buildup of resistance ofPhytophthora infestans to oxadixyl was studied in potato crops (cv. Alpha) grown in plastic houses. Half-rates of SAN 518F (mancozeb + oxadixyl)
applied weekly provided better disease control and reduced resistance buildup more effectively than the full rates of the
mixture applied biweekly. Mancozeb applied weekly at full rate was less effective than SAN 518F at half-rate. The data suggest
that lowering the dosage together with shortening the interval between sprays is an efficient strategy to combat mixed populations
— sensitive and resistant to phenylamides — ofP. infestans when phenylamide-based fungicidal sprays are used. 相似文献
5.
Propamocarb (Previcur-N; propyl-[3-dimethylamino-propyl] carbamate-monohydrochloride) was testedin vivo against 32 field isolates ofPhytophthora infestans from six countries. Fungicide dosages required to achieve 90% control of the blight ranged between 676 and 1530 ppm a.i.
in potted potato (cv. ‘Alpha’) plants and between 1135 and 2648 ppm in potato tuber slices. Isolates from Israel were less
sensitive to the fungicide than isolates from Europe or North America. Toxicity of propamocarb was not related to resistance
or sensitivity to phenylamide fungicides (e.g. metalaxyl). Nevertheless, most metalaxyl-resistant isolates from Israel were less sensitive to propamocarb than most metalaxyl-sensitive
isolates from this country. Monocyclic epidemics conducted with the 20 Israeli isolates in the field showed that 1081–2012
ppm of the fungicide was required to achieve 90% control of the disease. Laboratory experiments revealed that the fungicide
was poorly active against sporangial germination and had a limited curative efficacy. It exhibited a translaminar translocation
in leaves but a poor acropetal or basipetal systemicity from foliage. Propamocarb + mancozeb mixtures (1:1, v/w) were synergistically
effective in controlling the blight. Growers in Israel use tank mixtures of propamocarb (Dynone) and mancozeb to combat late
blight in potato fields where phenylamide-resistant isolates ofP. infestans are prevalent. 相似文献
6.
Potato crops (cv. Alpha) were grown in walk-in plastic tunnels (33 m2 ) in winter 1987 and spring 1988. Crops were left untreated or treated (four sprays at intervals of 2 weeks) with either metalaxyl, Ridomil-MZ (metalaxyl+ mancozeb) or Ridocym (metalaxyl +mancozeb+cymoxanil). Crops were inoculated with sporangial suspensions of Phytophthora infestans containing 01, 1 or 10% metalaxyl-resistant sporangia. Disease progress and percentage resistant sporangia in tunnels were estimated for a period of 50 days. In the treated crops cumulative disease, rate of disease progress and increase in frequency of resistant phenotypes (selection coefficient) were higher in metalaxyl-treated crops than in Ridomil-MZ or Ridocym-treated crops. Cumulative disease, rate of disease progress and increase in frequency of resistant phenotypes were unaffected by the frequency of resistant sporangia in the original inoculum. Metalaxyl, Ridomil-MZ and Ridocym speeded up the selection for resistance by 92, 29 and 17%, respectively, relative to untreated crops. The time interval required for the resistant subpopulation to predominate in treated crops was inversely related to initial resistance. It was longest in crops inoculated with 0.1 % resistant sporangia and treated with Ridocym. Results indicated that metalaxyl mixtures were advantageous over metalaxyl alone, both in delaying the buildup of resistance and in improving disease control, but did not prevent resistant subpopulations increasing from 01 to 100% in a single season. 相似文献
7.
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. 相似文献
8.
防治大豆疫霉根腐病的药剂筛选 总被引：14，自引：0，他引：14
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。 相似文献
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2003 ~2004年从内蒙古和黑龙江省共采集分离了127株马铃薯晚疫病菌Phytophthora infestans,并在离体条件下测定了这些菌株对甲霜灵和霜脲氰的敏感性。结果表明:在2003年分离的内蒙菌株、2003年及2004年分离的黑龙江菌株中对甲霜灵敏感(MS)的菌株频率分别为86.2%、13.8%、17.8%;虽然霜脲氰在这些地区使用近10年,但病菌群体对该药剂的敏感性没有下降,EC50值分布于0.10 ~0.35 μg/mL之间,平均EC50值为0.20(±0.06)μg/mL,不同敏感性的菌株频率呈连续的单峰曲线分布,未出现敏感性下降的抗药性亚群体,可作为马铃薯晚疫病菌对霜脲氰抗药性监测的敏感性基线;此外,马铃薯晚疫病菌对甲霜灵和霜脲氰之间没有交互抗药性,霜脲氰对抗甲霜灵和野生敏感菌株具有相同的活性。 相似文献
11.
Jean-Marc Albourie Jeanne Tourvieille Denis Tourvieille de Labrouhe 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(3):235-242
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. 相似文献
12.
A mixture (‘Fubol’) of metalaxyl with mancozeb, performed better than mixtures of propamocarb (as the hydrochloride) or the experimental fungicide cymoxanil with mancozeb, when applied as sprays to control potato blight in a small-scale field trial conducted in 1978. Another experimental fungicide, 2-chloro-N-(2-oxotetrahydrofuran-3-yl)acet-2″,6′-xylidide (RE 20615), applied at a greater rate but without mancozeb, was as effective as ‘Fubol’. The mixture of mancozeb and propamocarb or cymoxanil performed no better than mancozeb alone. In 1979, when blight incidence was greater, use of RE 20615/dithiocarbamate mixtures allowed the extension of spray intervals to 21 days, compared with a 14-day schedule for the dithiocarbamate alone. RE 20615, applied in 1979 to the soil within the furrows at planting time as a controlled-release granular formulation, gave adequate control of late blight up to early September, after which disease development accelerated. Yield was not significantly different from that obtained with a standard dithiocarbamate treatment. 相似文献
13.
Spray mixtures consisting of the plant activator BABA (DL-3-aminobutyric acid) and the protectant fungicide mancozeb were
significantly more effective than BABA or mancozeb alone in controlling late blight (Phytophthora infestans) in potato and tomato and downy mildew (Pseudoperonospora cubensis) in cucumber. A mixture composed of 5 parts BABA and 1 part mancozeb (w/w, a.i.) exhibited a higher synergy factor than the
1+1 or the 1+5 (BABA + mancozeb) mixtures. No synergistic interaction was detected between BABA plus mancozeb in controlling
sporangial or cystospore germination, nor mycelial growth ofP. infestans in vitro. The results showed enhanced effect of mancozeb in BABA-induced plants, suggesting, therefore, that lower dosages of this
fungicide may be sufficient to control late blight or downy mildew under field conditions.
http://www.phytoparasitica.org posting July 15, 2003. 相似文献
14.
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Potato tubers (cv. Alpha) were harvested at various time intervals after planting, or removed from storage at various times after harvest, and inoculated with different sporangial concentrations of three metalaxyl-sensitive (MS) and three metalaxyl-resistant (MR) isolates ofPhytophthora infestans. Disease parameters recorded were: (a) percentage of infected tubers; (b) percentage of blighted tuber surface area; and (c) depth of lesions. Blight was negatively correlated with tuber age both in the field and in storage. Susceptibility of tubers declined with age in the field but increased temporarily in storage.MR isolates did not differ significantly from MS isolates in percent of infected tubers but produced significantly larger and deeper lesions in tubers. Whereas inoculum concentration had a significant effect on the percent of infected tubers and of infected tuber surface area, it did not affect significantly the depth of the lesions. The results indicate that the MR isolates tested are stronger tuber blighters than the MS isolates. 相似文献
16.
The effects of seven adjuvants (at 0, 0.5, 1.0 and 2.0 g litre?1) on the efficacies of four fungicides al 0.5 g litre?1 were studied in the laboratory for the control of leaf-spot in celery (caused by Septoria apiicola) and powdery mildew on winter wheat (caused by Erysiphe graminis). The most effective fungicides for controlling leaf-spot were: tebuconazole + triadimenol = flutriafol > mancozeb + oxadixyl > prochloraz. However, addition of adjuvant to the fungicides gave a modified pattern of effectiveness. The efficacy of flutriafol was strongly enhanced by addition of all adjuvants, but those of prochloraz and mancozeb+oxadixyl only partially so. The tested adjuvants were mineral oil + surfactant, a polymer/alkoxylated alkyl ether blend, an ethoxylated alkylphenol, an ethoxylated hexitan ester blend, an ethoxylated nonylphenol and an alkylpolysaccharide- based adjuvant mixture. However, the addition of adjuvants to tebuconazole + triadimenol had a negative effect. Of all the adjuvants tested, the nonylphenol ethoxylate and a mixture of mineral oil /surfactant and alkylpolysaccharides gave the highest efficacy with the fungicides, while the mineral oil/surfactant and the alkylpolysaccharides alone were less effective. There was a positive relationship between high concentrations of adjuvants and their effectiveness, but there were some exceptions. The most effective fungicides for control of powdery mildew in wheat were prochloraz, mancozeb + oxadixyl and tebuconazole + triadimenol. There was a linear relationship between the high efficacy of the fungicide and the concentration of adjuvants to control powdery mildew in wheat. The highest concentration of adjuvant (2-0 g litre?1) gave the highest efficacy for the fungicides. 相似文献
17.
Seventeen metalaxyl-sensitive and 21 metalaxyl-resistant isolates ofPhytophthora infestans collected from blighted potato fields during the years 1983–1988 were tested for mating type on rye seed agar medium. All
isolates except one (MS3, collected in 1986 at Sufa, in the western Negev) were found to belong to the A2 mating type. A2
isolates produced oospores within 2 weeks when cultured together with isolate 163 (A1 from the U.S.A.) or with the A1 isolate MS3 from Israel. When cultured singly, A2 isolates produced some oospores within 4–8 weeks. Blighted potato tubers harvested from potato crops artificially inoculated
with a mixture of A1+A2 sporangia were found to contain some oospores. No oospores were detected in blighted tubers harvested
from A2 + A2 inoculated crops. It was concluded that the A2 mating type ofP. infestans has occurred in Israel since 1983 or even earlier. The rare occurrence of the A1 mating type was unexpected and indicated
that sexual reproduction of the fungus in the country might be limited. 相似文献
18.
Synergism of mixtures of pyrethroids with organophosphorus (OP) compounds in insects is reviewed, and the toxicity of such combinations againstSpodoptera littoralis (Boisd.) larvae is reported. Mixtures of one of the pyrethroids cypermethrin, fenvalerate or deltamethrin with one of the OP compounds monocrotophos, profenofos, azinphos-methyl or acephate were assayed at different ratios as 24-h-old dipping residues on alfalfa, which was fed toS. littoralis larvae for 48 h. With most of the binary mixtures containing various OP concentrations in excess of those of the pyrethroids, synergism was demonstrated. In the pairs fenvalerate — azinphos-methyl, deltamethrin — azinphos-methyl and deltamethrin — profenofos, however, no synergism was found. In a detailed investigation with pyrethroid concentrations causing 20% mortality and OP concentrations giving a kill of no higher than ;10%, the above findings on synergism were amply confirmed. A cypermethrinmonocrotophos mixture showed synergism also on cotton leaves sprayed in the field. Synergism could not be demonstrated by topical application of pyrethroid — OP mixtures. 相似文献
19.
L. C. DAVIDSE 《EPPO Bulletin》1985,15(4):403-409
In The Netherlands in 1980 a severe late-blight epidemic involving metalaxyl-resistant strains of Phytophthora infestans did considerable damage to the potato crop. As a consequence metalaxyl or metalaxyl-containing products were withdrawn from the Dutch fungicide market for the control of potato late blight. In 1981 the majority of the P. infestans isolates obtained from various parts of the country were sensitive to metalaxyl. In three areas where metalaxyl mixtures were used on a relatively large scale metalaxyl-resistant strains dominated the population. Incidental use of metalaxyl mixtures in 1982 and 1983 showed adequate late-blight control and, when in 1984 an early and in some areas severe epidemic developed, a metalaxyl/mancozeb mixture was reintroduced for curative application in combination with conventional fungicides. Although disease control was adequate, resistant strains were present in a small number of fields. Whether resistant strains will increase in frequency and threaten the usefulness of mixtures of acylalanines will heavily depend on how well potato farmers adopt strategies involving a limited use of mixtures of acylalanines in a spray schedule with conventional late-blight fungicides. 相似文献
20.
Leen C. Davidse Oda C.M. Gerritsma Grardy C.M. Velthuis 《Pesticide biochemistry and physiology》1984,21(3):301-308
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. 相似文献