Effect of Fungicides on Septoria nodorum and Wheat Green Leaf Area1

Fungicides applied at different growth stages were compared for the control of wheat glume blotch, caused by Septoria nodorum (Berk.) Berk. In glasshouse and small-scale field tests, 11 commercially used fungicides, when applied to fully emerged wheat ears, cv. Hobbit, gave only partial control of ear infection by spores applied immediately after spraying. They gave better control of infection of leaves by a similar inoculum. Larger field trials, moreover, indicated better foliar and ear disease control from fungicide applications made before ear emergence, compared with those applied later. In another field trial, nine fungicides were applied to replicated plots of winter wheat, cultivars Atou and Hobbit at GS 31, GS 39, GS 55 or GS 71. On five occasions from anthesis (25 June) until 30 July disease was assessed and green leaf area measured. The trial was harvested on 22 August 1980. Significantly greater yields and grain weights were obtained from plots sprayed with fungicide at GS 39 than from those sprayed at any other time or left unsprayed. Treatments made before symptoms of infection by S. nodorum developed (i.e. before GS 55) prolonged the duration of green leaf areas during the post-anthesis period. Grain weight and yield increases were related closely to the duration of green leaf area above 75 96, but not to the amount of green leaf area at any single assessment nor to the subsequent degree of disease development. The data on which this abstract is based form part of a continuing research programme, the results of which will be published in full at a later date. Full details on the 1980 results referred to above appear in the Annual Report of Long Ashton Research Station (1980).     

Unexpected Effects of Fungicides on Cereal Yields1

Field experiments with barley have generally shown a good relationship between disease and yield. However, in some experiments the yield response is greater than would be expected from the level of disease. In contrast, other trials have shown a reduction of yield following applications of tridemorph to spring barley. On winter wheat, trials in Germany have shown a poor relationship between disease incidence and yield following application of carbendazim or captafol at GS 30–31. About 10 96 of these responses were negative, although there was an average yield increase of 2–3 %. Similarly, in a series of trials in Britain an average yield increase of 3 % was not related to disease level. In these trials about 25 % of results showed no increase in yield. The carbendazim fungicides, and also certain others, have some cytokinin-like activity and it is possible that this is related to extended green leaf survival. Other interactions with host-cell chemistry can be envisaged. Fungicides also influence stability of the leaf microflora. By this effect they may favour diseases such as Typhula and Rhizoclonia, or else suppress secondary pathogens (Alternaria, Cladosporium) at the end of the season.     

几种杀菌剂对小麦条锈病田间防治效果研究

小麦条锈病(Puccinia striiformis West.f.sp.tritici Eriks et Henn)是小麦生产上的重要病害,该病在赫章县发生面积大,流行速度快,常给小麦生产造成重大损失。目前,除了选育抗病品种、开展小麦秋播拌种、处理发病中心外,化学防治仍然是减轻小麦条锈病发生程度的有效措施。本试验引进几种杀菌剂进行药效对比试验,结果表明戊唑·百菌清75%可湿性粉剂、三唑酮15%可湿性粉剂对小麦条锈病防治效果达80%以上,增产幅度40%以上,生产中可以推广应用。     

甲氧基丙烯酸酯类杀菌剂研究进展

甲氧基丙烯酸酯类杀菌剂是一类重要的新型杀菌剂,具有广谱、高效、安全的特点.本文从它的开发背景和现状、杀菌活性、作用机理和抗性研究等方面对甲氧基丙烯酸酯类杀菌剂的研究进展进行了综述.     

Factors that Affect Spread of Pseudomonas syringae in the Phyllosphere

ABSTRACT Successful spread of an organism to a new habitat requires both immigration to and growth on that habitat. Field experiments were conducted to determine the relative roles of dispersal (i.e., immigration) and bacterial multiplication in spread of Pseudomonas syringae pv. syringae in the phyllosphere. To study spread, individual plots consisted of three nested concentric squares with the inner 6 m(2) planted to snap beans serving as the sink. Each sink, in turn, was surrounded by a barrier zone, usually 6 m wide, which was surrounded by a 6-m-wide source area. The source areas were planted with snap bean seeds inoculated with doubly marked strains derived from wild-type P. syringae pv. syringae B728a. The treatments were designed to test the effects of the nature and width of the barrier zone and suitability of the habitat in the sinks on spread of P. syringae pv. syringae. The marked strains introduced into the source areas at the time of planting were consistently detected in sink areas within a day or two after emergence of bean seedlings in the sources as assessed by leaf imprinting and dilution plating. The amounts of spread (population sizes of the marked strain in sinks) across barrier zones planted to snap bean (a suitable habitat for growth of P. syringae pv. syringae), soybean (not a favorable habitat for P. syringae pv. syringae), and bare ground were not significantly different. Thus, the nature of the barrier had no measurable effect on spread. Similarly, spread across bare-ground barriers 20 m wide was not significantly different from that across barriers 6 m wide, indicating that distance on this scale was not a major factor in determining the amount of spread. The suitability of the sink for colonization by P. syringae pv. syringae had a measurable effect on spread. Spread to sinks planted to clean seed was greater than that to sinks planted with bean seeds inoculated with a slurry of pulverized brown spot diseased bean leaves, sinks planted 3 weeks before sources, and sinks planted to a snap bean cultivar that does not support large numbers of P. syringae pv. syringae. Based of these results, we conclude that the small amount of dispersal that occurred on the scale studied was sufficient to support extensive spread, and suitability of the habitat for multiplication of P. syringae pv. syringae strongly influenced the amount of spread.     

灭线磷降解菌DS-1在土壤中的定殖及对常用杀菌剂的敏感性

测定了3种灭线磷降解菌的降解能力,结果表明,三株能够较好降解灭线磷的细菌DS-1、F2和G2中,DS-1对灭线磷的降解效果最好,采用平板计数法对DS-1田间定殖及灭线磷降解实验的研究表明,土壤接菌14d后DS-1的生长达到最高峰,随后逐渐衰退,加灭线磷的处理DS-1菌数量明显高于其他不加灭线磷的处理,说明DS-1主要利用灭线磷生长;DS-1对灭线磷的降解实验表明,加DS-1菌液的灭菌土中灭线磷的降解率高于同样条件下的非灭菌土中灭线磷的降解率,加菌液的灭线磷的降解率高于不加菌液的灭线磷的降解率,说明灭线磷的降解主要依靠DS-1。田间常用杀菌剂对灭线磷降解菌DS-1的生长及灭线磷降解的影响研究表明,保护性杀菌剂对DS-1的生长以及灭线磷的降解影响较大,内吸性杀菌剂对两者的影响较小。     

几种常用杀菌剂对马铃薯晚疫病防治效果比较研究

试验表明50%烯酰吗啉等九种杀菌剂对马铃薯晚疫病发病初期均有好的防效,药后7d防效均在81.5%以上。在马铃薯晚疫病初期施药,各药剂防效差异明显。第2次用药后7d,50%烯酰吗啉水分散粒剂、70%丙森锌可湿性粉剂、60%吡唑醚菌酯/代森联水分散粒剂、72%霜脲·锰锌可湿性粉剂对马铃薯晚疫病防治效果在83%以上,且最后增产效果均在40%以上。而70%甲基硫茵灵可湿性粉剂等其它5种药剂的防病效果只在70%左右,增产幅度也低。各药剂对马铃薯安全,无药害表现。建议向农民首推50%烯酰吗啉水分散粒剂防治马铃薯晚疫病,其次是72%霜脲·锰锌可湿性粉剂、70%丙森锌可湿性粉剂和60%吡唑醚菌酯/代森联水分散粒剂。     

Role of Fungicides in Maximizing Grain Yield of Barley1

Application of fungicides to cereals normally increases grain yield, this usually being accounted for by control of well-defined diseases. Sometimes, however, yield increases are obtained when apparently trivial amounts of defined diseases are present or when their control seems insufficient to explain the observed benefit. Explanation for these ← unexpected → increases have been sought in: a) control of ← weak → pathogens or organisms not considered pathogenic but which may accelerate leaf senescence, and b) direct effects of fungicides on the plant's physiology. Whatever the precise explanation in individual instances, we may ask whether there is some general relationship linking fungicidal action, plant growth and yield. In barley, recent studies of controlled epidemics of powdery mildew have shown: a) that there is a strong correlation between severity and duration of mildew and reduction in green leaf area (GLA) integrated over time; b) that the grain yield of plants is highly correlated (r values often approaching unity) with values of GLA integrated for the period from seedling emergence to anthesis. The data also show that retranslocation of stored carbohydrate, produced before anthesis, plays an important role in grain filling, and indicate that mildew post anthesis may have little effect on yield. The main implication of these studies is that, in barley, fungicide treatments which increase GLA prior to anthesis are likely to enhance yield. Evidently this may be achieved by different means (control of pathogens, including ← weak → pathogens, or by directly extending the functional life of leaves); the end result, in terms of grain yield, will, however, be the same.     

Effect of Three Seed-dressing Fungicides on the Germination of Cowpea,Groundnut and Maize

Abstract

Agrosan 5W, Fernasan D and Quinolate 15/40 significantly improved the germination, under field conditions, of the seeds of cowpea (variety Mezed), groundnut (variety Chimbuila) and maize (variety NSI), but not that of cowpea (variety New era) and groundnut (variety Spanish 205).

In those cases where the application of seed-dressing was effective, treatment with Agrosan 5W appeared to give better germination than treatment with either Fernasan D or Quinolate 15/40. Maize seeds treated with Quinolate 15/40 germinated slightly better than those treated with Fernasan D, whereas treatment of cowpea and groundnut seeds with Fernasan D gave better germination than treatment with Quinolate 15/40.

A similar trend was observed in tests in vitro.     

六种杀菌剂对黄瓜霜霉病菌不同发育阶段的影响

用Calcofluor荧光染色和显微观察的方法研究了6种常用杀菌剂对黄瓜霜霉病菌Pseudoperonospora cubensis不同发育阶段的影响。结果表明:烯酰吗啉和氟吗啉对黄瓜霜霉病菌孢子萌发、芽管伸长、附着胞形成、菌丝扩展、孢囊梗和孢子囊的形成具有明显的抑制作用,其EC50值分别在0.07~5.98 μg/mL和0.10~3.50 μg/mL之间,而对游动孢子释放、游动孢子游动和休止孢形成没有抑制作用;霜脲氰对休止孢萌发和芽管伸长的EC50值分别为1.10和0.002 μg/mL,对其他阶段无明显的抑制效果;腈嘧菌酯对休止孢萌发、菌丝扩展和孢囊梗产生无影响,对游动孢子释放、芽管伸长和附着胞形成的EC50值分别为0.018、0.008和0.010 μg/mL;代森锰锌对游动孢子释放、休止孢萌发和芽管伸长的EC50值分别为2.40、2.88和1.53 μg/mL;甲霜灵对该菌的整个发育期均没有影响,这可能是因为供试菌株对甲霜灵已经产生了抗药性。     

Effect of Fungicides on Fusarium Head Blight and Deoxynivalenol Content in Durum Wheat Grain

In 1998–99 and 1999–2000 six trials were conducted to evaluate the effect of fungicides on Fusarium head blight in the field, on infected kernels and deoxynivalenol (DON) concentration in grain. A single application of prochloraz, tebuconazole, epoxiconazole or bromuconazole, applied to durum wheat varieties at the manufacturer's recommended dose at the beginning of anthesis stage, provided good control of the disease when infective pressure in the field was low to medium, and when the main pathogens were F. graminearum and F. culmorum. Kresoxim-methyl showed a low efficacy at controlling the disease. Tebuconazole, prochloraz and bromuconazole were effective at controlling F. graminearum and F. culmorum, while kresoxim-methyl was not effective in reducing Fusarium infected kernels. DON concentration in grain of cultivars inoculated with F. graminearum and F. culmorum was high, averaging 4.2mgkg^–1 (untreated control). Tebuconazole, prochloraz and bromuconazole reduced DON concentration by 43%, while epoxiconazole was ineffective. DON concentration in kernels of naturally infected cultivars was 1.95mgkg^–1, a concentration which exceeds the 1mgkg^–1 maximum level of contamination allowed in the United States. Furthermore prochloraz, bromuconazole and tebuconazole applications, in the naturally inoculated trials, reduced DON concentration from 73% to 96%, while epoxiconazole showed the lowest effectiveness. Moreover, a positive linear correlation between Fusarium infected grains and the DON concentration was observed.     

5种药剂对西瓜炭疽病的田间防治效果研究

为筛选防治西瓜炭疽病的高效、低毒药剂,本研究通过田间试验的方法比较了啶氧菌酯、嘧菌酯、吡唑醚菌酯、苯醚甲环唑及苯甲·嘧菌酯5种药剂对西瓜炭疽病的控制效果.试验结果表明,啶氧菌酯150g/hm2、啶氧菌酯180g/hm2、嘧菌酯225g/hm2、吡唑醚菌酯150g/hm2、苯醚甲环唑60g/hm2以及苯甲·嘧菌酯195g/hm2在西瓜炭疽病发病初期施药,间隔7～10d施药1次,连续施药3次,末次药后7d的防效分别为68.81％～70.10％、71.22％～73.10％、61.65％～63.98％、70.67％～72.18％、73.29％～75.06％和69.68％～71.26％,嘧菌酯的防效略差于其他各处理,啶氧菌酯180g/hm2及苯醚甲环唑60g/hm2的防效略优于其他各处理,但各处理之间防效差异并不显著,5种药剂均能较好的防治西瓜炭疽病.     

农用杀菌剂开发的新进展

本文对近期开发的农用杀菌剂作了简要的介绍。文中涉及三唑类、吡咯类、苯（苄）胺基嘧啶类、恶（咪）唑啉酮类、甲氧基丙烯酸酯类、氨基酸衍生物和酰胺类等化合物的结构、生物活性、作用机理以及应用等。     

生物源杀菌剂与化学杀菌剂协调防控黄瓜病害

本文研究枯草芽孢杆菌Bacillus subtilis BAB-1水剂、解淀粉芽孢杆菌B.amylololiquefaciens SAB-1水剂、大花旋覆花内酯乳油与化学杀菌剂交替或混合使用对温室黄瓜病害发展的影响.寿光试验包括以下处理:交替或混合喷施50%啶酰菌胺WG、68.75%氟吡菌胺·霜霉威SC的桶混液、60%唑醚·代森联WG、40%嘧霉胺SC、50%烯酰吗啉WP、10%苯醚甲环唑WG、69%烯酰·锰锌WP、68.75%噁唑·锰锌WG、52.5%噁唑·霜脲氰WG等不同作用机理和防治谱的化学杀菌剂;混施生防菌剂BAB-1水剂、SAB-1水剂及68.75%氟吡菌胺·霜霉威SC、50%烯酰吗啉WP、25%双炔酰菌胺SC、25%吡唑醚菌酯EC等对霜霉病特效化学杀菌剂;将不同化学杀菌剂桶混液与BAB-1水剂、SAB-1水剂和化学杀菌剂桶混液交替喷施.其对黄瓜霜霉病的防效分别为94.5%、92.3%和93.6%,对黄瓜白粉病分别为90.7%、89.9%和90.4%,对灰霉病的防效分别为69.3%、85.6%和85.7%,每种病害的病害发展曲线下面积(AUDPC)相当.在定州试验中,化学杀菌剂与SAB-1混施对白粉病的防效(84%)明显高于其与BAB-1混施的防效(72.8%),对灰霉病的防效(61.3%)明显低于后者的防效(95.1%),与SAB-1、BAB-1混施后对白粉病、灰霉病及霜霉病防效分别为90.2%、89.3%和92.6%.在保定郊区试验中,将大花旋覆花内酯乳油与化学杀菌剂及BAB-1水剂、SAB-1水剂交替喷施显著降低霜霉病、白粉病及灰霉病的严重度及AUDPC,对其防效分别为83.5%、87.4%和88.5%,AUDPC分别为219、352和249,延缓了3种黄瓜病害的发展.     

杀菌剂对辣椒疫霉菌的毒力及其所致番茄猝倒病的控制效果研究

实验室接种条件下比较了6种杀菌剂对辣椒疫霉菌Phytophthora capsici Leonian引起的番茄猝倒病的控制作用,室内测定了其对致病菌菌丝生长、孢子囊形成、释放游动孢子3种不同菌态的毒力。结果表明:在对番茄安全的剂量下进行土壤处理时, FDA3 霉灵、稻瘟灵对番茄猝倒病的防效为80%~90％,霜霉威和代森锰锌的防效为60%~70％,甲霜灵和异菌脲的防效在50％左右;供试杀菌剂浸种处理对番茄猝倒病的防效都较低,均在60％以下。甲霜灵对致病菌菌丝生长、孢子囊形成、释放游动孢子的毒力最高,EC50值分别为0.304、0.742和2.725 mg/L; FDA3 霉灵、稻瘟灵对致病菌孢子囊形成的毒力较高,EC50值分别为0.875和2.888 mg/L,但对菌丝生长和释放游动孢子的EC50 值均在20 mg/L以上;代森锰锌的毒力中等,对3种菌态的EC50值分别为3.402、10.243和23.561 mg/L;霜霉威和异菌脲对病原菌3种不同菌体形态的毒力都较低,EC50＞100 mg/L。     

几种杀菌剂对草莓白粉病的防效研究

在温室大棚用苯醚甲环唑、苯醚甲环唑+丙环唑、氟硅唑、腈菌唑和三唑酮等杀菌剂防治草莓白粉病Sphaerotheca aphanis。结果表明,适宜浓度的 10%苯醚甲环唑WG、30%苯醚甲环唑+丙环唑EC、40%氟硅唑EC、20%三唑酮EC、12.5%腈菌唑EC的田间防治效果均可达到80%以上;苯醚甲环唑、苯醚甲环唑+丙环唑、氟硅唑和三唑酮的持效期约为18 d,而腈菌唑的持效期较短,约为7 d。10%苯醚甲环唑WG在360~900 g/hm2用量时不影响草莓长势,而氟硅唑225 mL/hm2和三唑酮300~450 mL/hm2用量时则在不同程度上抑制草莓的生长。