Selection of biological control agents for controlling soil and seed-borne diseases in the field

Different screening methods for selection of biological control agents (BCAs), for controlling soil and seed-borne diseases, are discussed. The shortcomings of laboratory methods focused on mechanism of action are discussed and we conclude that these methods should be used with caution if candidates with multifactorial or plant mediated mechanisms of control are to be obtained. In vitro screens may be useful for specific groups of microorganisms, thus, screens for antibiotics may be relevant for Streptomyces spp., and promising results have been obtained using soil plating or precolonized agar methods to screen for mycoparasitism and competitive saprophytic ability. Experience with screening in the Nordic programme Biological control of seed borne diseases in cereals is summarized. Research in the four participating countries – Finland, Sweden, Norway and Denmark – followed the same paradigm: that of obtaining antagonists, well adapted to different Nordic environments, and developing them as effective BCAs. Potential antagonists were isolated from different sources and in planta screening methods were developed in order to optimize selection of antagonists effective against a range of seed borne pathogens. Screens in the laboratory or greenhouse were followed by screening in the field. The different screening procedures are compared and evaluated.     

杀菌剂Fulicur与Caramba防治小麦条锈病的研究

Fulicur与Caramba对小麦条锈病具有优异的保护和治疗作用 ,用药量省 ,持效期长。温室试验结果表明 ,使用Fulicur 1.15mL/L、Caramba 1.75mL/L对小麦叶片具有很好的保护作用 ,对已发病的小麦叶片能够铲除叶片内的病菌 ,达到治愈的目的。田间试验结果表明 ,孕穗期一次用药可保证整个生育期不被侵染 ,发病后用药 ,防效可达 95%以上 ,效果略高于三唑酮的常规用量     

Recent studies on biological control of plant diseases in Japan

Microorganisms play an enormously important role in plant disease control. Research on biological control of plant pathogens has received major impetus and attracted many researchers during the past few decades due to the increased public concern on hazards associated with the use of synthetic pesticides. From research on utilizing specific antagonistic microorganisms, many effective biological control agents (BCAs) have been found and are increasingly implemented in integrated pest management strategies to control plant diseases. Here current research results on biological control against plant diseases carried out in Japan are reviewed by focusing on major categories of BCAs: fungi, bacteria and actinomycetes and attenuated viruses.     

警惕小麦冠腐病发生及时做好病害防控

由假禾谷镰刀菌(Fusarium pseudograminearum O'DonnellT.Aoki)引起的小麦冠腐病(wheat crown rot)是我国小麦生产上新发生的病害,发展迅速,为害严重。为此,对其症状、国内外发生现状、病原学研究、病害发生成因、风险评估及防控措施等进行了综述,并为今后对小麦冠腐病的深入研究进行了展望。     

农田有害生物暴发性灾害分析

近年我国农田有害生物暴发性灾害发生频率呈不断上升趋势,已成为制约农业高产、优质、高效益持续发展的主导因素之一。迁飞性害虫大量迁入降落、生态环境的破坏、生物多样性的降低、自然因素的不正常变化、预测和防治技术的滞后以及有害生物的入侵是导致农田有害生物暴发性害灾频发的因素。改进农田有害生物灾害预测技术、保护和改良农田生态系统、提高控制农田有害生物灾害的技术水平、加强植物检疫是控制农田有害生物暴发性灾害的途径。     

作物混植和间作控制病虫害研究的新进展

通过作物的混植和间作,可以有效地提高作物群体的抗性水平,以达到自然控制病虫害的目的。从混植和间作的模式、控害效果和控害机制等方面对这一研究的最新进展进行了综述,并讨论了作物混植和间作的优越性、应用特点和当前的研究重点。     

Relating epidemic progress from a general disease model to seasonal appearance time of rusts in the United States: implications for soybean rust

ABSTRACT Soybean rust, Phakopsora pachyrhizi, has been considered a threat to the production of the U.S. soybean, Glycine max. During the past decade, this disease gradually spread to Africa, South America, and recently to the United States. Previous soybean rust risk assessments with an assumption of availability of spores early in a season showed that weather conditions (dew and temperature) during a growing season, in general, are suitable for disease development in U.S. soybean-growing regions. Predicting the time of rust appearance in a field is critical to determining the destructive potential of rusts, including soybean rust. In this study, comparative epidemiology was used to assess likely rust incipient time in four locations within the U.S. Soybean Belt from south to north: Baton Rouge, LA; Charlotte, NC; Indianapolis, IN; and Minneapolis, MN. Temperature effects on the infection cycle of five rusts occurring in the Midwest were evaluated using a general disease model. The likely incipient times were examined with the modeling results. Among the rusts studied, early-appearing rusts had suitable conditions for development earlier in a season. However, a lag period of several weeks to more than 3 months was found from the time when conditions are suitable for a rust to develop or when hosts are available to the time when the rust was detected in fields. Length of the lag period differed among the rust species examined. If nature of long-distance dispersal is not significantly different among the rusts, implications of our study to the expected seasonal soybean rust incipience in fields lead to two possible scenarios: (i) average appearance time of soybean rust across the Soybean Belt should be somewhere between appearance times of common corn rust and southern corn rust, and (ii) with late appearance of the disease, late-planted soybean in the south has greater risk.     

防治玉米顶腐病和黑粉病药剂筛选

采用10种杀菌剂对玉米顶腐病菌室内测定结果表明,80%多&;#8226;福&;#8226;福锌可湿性粉剂、70%多&;#8226;福可湿性粉剂、97%多菌灵可湿性粉剂和98%烯唑醇可湿性粉剂抑菌效果最好,而且持效期较长。以97%多菌灵可湿性粉剂和98%烯唑醇可湿性粉剂按3〖DK1〗∶1或4〖DK1〗∶1的比例进行复配,抑菌效果达到了其各自单用的抑菌效果。经安全性测定,用98%烯唑醇可湿性粉剂进行种子包衣在低温条件下对玉米出苗和苗期生长有一定影响,97%多菌灵可湿性粉剂则无影响。田间防治试验表明,97%多菌灵可湿性粉剂或97%多菌灵可湿性粉剂与98%烯唑醇可湿性粉剂复配对玉米顶腐病和瘤黑粉病均有一定防效。在玉米4～8叶和8～12叶期时,以97%多菌灵可湿性粉剂20 g+有机硅5 mL/666.7 m2和97%多菌灵可湿性粉剂25 g+98%烯唑醇可湿性粉剂5 g+有机硅7 mL/666.7 m2用量分别喷洒,对顶腐病的防治效果达90%左右,并可兼治瘤黑粉病,防治效果达70%左右。     

对控制农作物生物灾害的政府职能分析

农作物生物灾害(病、虫、草、鼠害等)种类繁多,发生频繁,严重地影响着农业生产和国家粮食等农产品及作物生态环境的安全,所以政府在生物灾害的控制中应起主导和决定性的作用。本文试分析政府的控害职能,以加强对农作物生物灾害的控制,确保农业生产安全。1控制农作物生物灾害政府职能的特点农作物生物灾害有3个显著的特点:一是为害农作物的有害生物种类多,发生面广,频率高。在我国,为害农作物的病、虫、草、鼠害超过2000种,其中大面积严重为害农作物的病、虫害有100种以上,有些病虫1a发生多个代(次),各类作物各生育期都可能遭遇到病虫的为害;…     

Cultivar mixtures for the simultaneous management of multiple diseases: tan spot and leaf rust of wheat

ABSTRACT Because of differences in life histories between Puccinia triticina, a highly specialized, polycyclic, windborne pathogen with a shallow dispersal gradient, and Pyrenophora tritici-repentis, a residue-borne pathogen with a steep dispersal gradient, wheat mixtures are expected to be more effective at controlling leaf rust than tan spot. The objectives of this research were to determine the effect of two-cultivar mixtures with varying proportions and different pathogen resistance profiles on the severity of tan spot and leaf rust, to evaluate yield of the mixtures in the presence or absence of disease, and to directly compare the relative effectiveness of cultivar mixing for tan spot versus leaf rust. In a field experiment at two sites in Kansas over two growing seasons, winter wheat cvs. Jagger and 2145, which have differential resistance reactions to leaf rust and tan spot, each were planted in proportions of 0.25, 0.50, 0.75, and 1.00. Plots were inoculated with each pathogen alone, both pathogens, treated with a fungicide, or exposed to ambient conditions. For both diseases for all siteyears, severity decreased substantially on the susceptible cultivar as the proportion of that cultivar decreased in mixture. Mixtures were significantly more effective at reducing leaf rust than tan spot in three of four site-years. Mixtures generally yielded the same as the weighted mean of components in monoculture although, in two of three site-years, at least one fungicide-treated and one diseased mixture each yielded higher than expected values. Although this particular mixture produced only modest yield benefits, the potential for simultaneous reductions in tan spot and leaf rust was demonstrated.     

Surveys of cereal diseases and pests in the Netherlands. 4. Occurrence of powdery mildew and rusts in winter wheat

Results of annual surveys of winter wheat fields from 1974 to 1986 were compiled to describe epidemics of powdery mildew and rusts in relation to weather and cultivar resistance.An average of 29 and 70% of fields were infected by powdery mildew in May and July, respectively. Mildew prevalence in May was positively correlated with average temperature in October and with average temperature over the months December, January, February and March. In addition, it was correlated negatively with the average grade of mildew resistance of the cultivars sown each year. Prevalence of mildew in July did not show consistent correlations with weather characteristics nor with mildew prevalence in May.Yellow rust was usually not detected in May and on average 18% of the fields was infected in July. The occurrence of yellow rust decreased after 1977, when the farmers adopted cultivars resistant or moderately resistant to yellow rust.Brown rust was usually not detected in May, while in July on average 48% of the fields was infected. Brown rust intensity in July was high in years with a high March temperature and high precipitation during April and May.Black rust was rare in the Netherlands, with 3 and 1% of the fields infected in July 1977 and 1981, respectively.     

南充市小麦条锈病流行成因及治理对策

1999-2003年,在四川省南充市对小麦条锈病的田间流行特点及影响病害流行主要因子进行系统调查明确,小麦品种抗锈性丧失是该市近年小麦条锈病流行的基础。外来菌源大范围传入是该病流行的前提。适时化学防治是避免该病大区域流行的最有效手段。通过试验提出了相应的治理对策。     

Carabidae as potential biological agents for controlling infestations of the cabbage root fly

Laboratory tests with carabid ground beetles found in Wellesbourne fields indicated that intermediate-sized beetles such asBembidion tetracolum, Amara familiar is andAgonwn dorsale were more effective predators of cabbage root fly (Erioischia brassicae) eggs than small beetles, e.g.Bembidion lampros andTrechus quadristriatus, or large beetles, e.g.Harpalus rufipes andPterostichus melanarius. Further tests indicated thatA. dorsale would be an ideal predator, as it can survive up to one month without food, is not killed byP. melanarius, aggregates naturally, and eats large numbers of cabbage root fly eggs/larva.A. dorsale is also relatively easy to retain near the stems of plants by simple barriers and is not cannibalistic. Unfortunately, sufficientA. dorsale were not available for greenhouse trials. Greenhouse trials withB. tetracolum indicated that two beetles per plant were sufficient to control the high levels of cabbage root fly infestation normally encountered in the field at Wellesbourne.     

冬枣锈病大发生原因分析及防治对策

冬枣作为一种鲜食果品,由于具有良好的品质备受青睐。近年来,滨州市冬枣产业迅猛发展,成为农民增收的新亮点。2004年本市沾化、无棣等县冬枣主产区,由于受气候、管理等因素综合影响,冬枣锈病大面积发生流行。据调查,发生较轻的枣园一般减产10%～20%,严重的达50%以上。笔者在大量田间调查的基础上,认真分析了该病重发的原因,并提出了相应的防治对策。1发生特点1)发病早,传播速度快,持续时间长。7月初始见病叶并迅速成为发病中心,向外大范围传播蔓延,7月20日前后枣园发病率80%,7月30日达90%,8月上旬部分枣园开始落叶,一直持续到9月中旬,仍有新…     

农作物生物灾害的形势与对策

湖南是农业大省,也是农业有害生物的重发区。据研究,为害本省农作物的有害生物种类在1 000种以上,常年发生种类超过100种。受多方面因素的影响,农作物生物灾害发生日趋严重,全省发生面积从20世纪80年代中期的2 500万hm2次上升到近年的3 300万hm2次,年均经济损失100亿元以上。在部分年份、部分区域,甚至大面积成灾。生物灾害的为害损失已超过水灾、旱灾,成为新时期制约湖南农业可持续发展的重要因素,对粮食生产、农业生态和食品质量安全构成了严重威胁。     

控氮增钾控制小麦病害发生试验

在宜城市和枣阳市开展控氮增钾控制小麦病害发生的试验研究。结果表明,合理控施氮肥和增施钾肥,可控制小麦病害的发生,收到增产、增收的效果。田间所施氮肥量与病害之间呈正相关关系。当所施纯氮在0～20kg/667m2之间时,随着施用量的增加,病害发生和为害呈上升加重趋势。根据收益分析,在小麦生长的全生育期内,田间每667m2施纯氮10～12.5kg较适宜。增施钾肥不仅能延迟小麦条锈病的始见期,还能明显降低条锈病、纹枯病、赤霉病等的发生程度,减轻其为害。同时,适量增施钾肥还能增加小麦千粒重,提高小麦产量。在每667m2施10kg纯氮和5kg纯磷的情况下,以施纯钾肥11kg产量最高。     

Relationships between temperature and latent periods of rust and leaf-spot diseases of groundnut

The effect of temperature on the latent periods of rust, late leaf spot and early leaf spot diseases of groundnut caused by Puccinia arachidis, Phaeoisariopsis personata and Cercospora arachidicola , respectively, was studied. The latent periods (LP) of rust, late leaf spot and early leaf spot ranged from 12–49 days, 13–38 days and 13–39 days, respectively, between 12°C and 33°C An equation relating the rate of pathogen development (1/LP) to temperature was fitted using daily mean temperatures to provide three cardinal temperatures: the minimum (T_mln), optimum (T_opl), and maximum (T_max), T_mln was about 12°C for rust and about 10°C for the two leaf-spot diseases. T_opt, for all three diseases was close to 25°C. T_max was 31°C for early leaf spot, and extrapolated values for late leaf spot and rust were about 35 and 40°C, respectively.
For P. personata , a temperature response curve was fitted using data only from controlled environment experiments. This curve was used to simulate latent periods from both mean daily and mean hourly temperatures in the field. There was substantially better agreement between observed and simulated latent period with hourly temperatures, provided the developmental rate of the pathogen was determined at a constant temperature.     

United States Department of Agriculture-Agricultural Research Service research programs in biological control of plant diseases

A number of USDA-ARS programs directed at overcoming impediments to the use of biocontrol agents on a commercial scale are described. These include improvements in screening techniques, taxonomic studies to identify beneficial strains more precisely, and studies on various aspects of the large-scale production of biocontrol agents. Another broad area of studies covers the ecological aspects of biocontrol agents-their interaction with the pathogen, with the plant and with other aspects of the environmental complex. Examples of these studies are given and their relevance to the further development and expansion of biocontrol agents is discussed.     

平凉市小麦条锈病发生流行趋势预测模型研究

通过对平凉市25年(1984～2008年)的小麦条锈病病情和气象资料综合分析,筛选出影响本市小麦条锈病越夏菌量、秋苗发病、翌年春季流行趋势的主要因子,并应用逐步回归方法建立了本市小麦条锈病越夏菌量、秋苗发病、翌年春季流行趋势预测模型.回测结果表明,模型预测准确率达73.9%～82.6%.对准确预测小麦条锈病短、中、长期发生流行趋势,指导当地乃至全国冬麦区适期开展综合治理、及时控制其为害,有着重要的作用.     

花椒绵粉蚧生活习性观察及防控技术研究

针对毁林新害虫花椒绵粉蚧的发生为害,重点研究了其在山西省的发生分布、生活习性、发生规律和综合防治技术措施。