香梨上山楂叶螨自然种群连续世代生命表分析     

蒋世铮  任德新  张文忠  赛买提江 《植物保护》2012,38(3):36-39

本研究对香梨园各世代山楂叶螨种群生命表的趋势动态指数I、控制指数(EIPC)、关键虫期、关键因子、关键因子与种群密度关系进行分析,建立最优回归预测方程,以评价影响山楂叶螨种群发展的各因子的作用。结果表明,山楂叶螨种群11代的种群趋势指数分别为0.98、8.90、3.74、0.87、0.41、0.22、0.02、1.00、2.09、2.23、2.97。"捕食及其他"和"自然死亡"因子是影响山楂叶螨种群各世代数量动态的重要因子。幼螨期是山楂叶螨的关键虫期,在幼螨期的"捕食及其他"因子是关键因子,关键因子是山楂叶螨种群变化的迟滞密度制约因子。  相似文献   

Characterization of Pseudomonas syringae pv. syringae isolates associated with bacterial blight in Lathyrus spp. and sources of resistance     

Alberto Martín-Sanz  José Luis Palomo  Marcelino Pérez de la Vega  Constantino Caminero 《European journal of plant pathology / European Foundation for Plant Pathology》2012,134(1):205-216

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Relationships between agronomic factors and epidemics of Phytophthora branch canker of citrus in southwestern Spain     

Antonio Vicent  Paloma Botella-Rocamora  Antonio López-Quílez  Elena de la Roca  Juan Bascón  José García-Jiménez 《European journal of plant pathology / European Foundation for Plant Pathology》2012,133(3):577-584

Phytophthora branch canker, caused by Phytophthora citrophthora, has been an increasing problem in clementine (Citrus reticulata) production in Spain during last years. The disease was particularly severe in the new citrus-growing areas of the southwestern coastal areas in Huelva Province. Recent studies revealed that disease emergence was not related to either genetic drift or host specificity changes in P. citrophthora population. Therefore, the possible association of agronomic factors with the disease was investigated. A total of 110 orchards were selected arbitrarily from the main citrus-growing areas in Huelva Province. The presence of branch cankers together with agronomic factors including soils, cultivars, rootstocks, irrigation, pruning, techniques to improve fruit production, fungicide treatments, presence of brown rot of fruit and frost damage were recorded. Logistic regression analysis was used to detect correlations between the agronomic factors studied and disease prevalence. Phytophthora branch canker was significantly associated with mature clementine orchards. Sweet orange and hybrid cultivars as well as young clementine orchards were less affected by the disease. Although disease was less frequent in Salorthid soils, alternative high resolution procedures are required to draw conclusions about the effect of soil properties on disease prevalence. As in other Phytophthora-induced diseases, soil flooding during the rainy season was correlated positively with the prevalence of branch cankers. Improving fruit production by branch scoring showed a strong positive correlation with Phytophthora branch canker. This is the first time that girdling has been associated with Phytophthora disease epidemics on a fruit tree crop, but further research is needed to determine the cause of this relationship. Cultural practices including pruning, regulated deficit irrigation, additional phosphonate sprays, and abiotic and disease factors such as frost damage and presence of brown rot of fruit were not significantly correlated with disease prevalence.  相似文献   

不同条件下韭菜汁对香蕉枯萎病菌4号小种活性抑制的研究   总被引：1，自引：0，他引：1  

刘任  杨静美  梁小媚  陈雁  冯岩  杜洪忠 《植物检疫》2012,(2):13-16

研究了不同温度、pH值、杀虫剂和杀菌剂的影响下,韭菜汁对香蕉枯萎病菌4号小种的抑制作用,以确定韭菜汁在不同条件影响下对病菌的活力。结果表明,在试验的各温度处理后,55℃以上的温度对韭菜汁的成分有破坏作用,菌落的生长受到显著影响。韭菜根汁对病菌孢子的抑制作用不受pH值的影响。酸性至弱碱性情况下,韭菜茎汁对病菌孢子萌发的抑制率为100%;在强碱性条件下,韭菜茎汁中物质的活性促进了孢子的萌发。供试杀虫剂和杀菌剂对韭菜汁的成分无明显破坏作用。  相似文献   

Soil amendments with Brassica cover crops for management of Phytophthora blight on squash     

Ji P  Koné D  Yin J  Jackson KL  Csinos AS 《Pest management science》2012,68(4):639-644

BACKGROUND: Phytophthora blight induced by Phytophthora capsici is responsible for serious yield loss in vegetable production in the United States and other countries. This study was conducted to evaluate the efficacy of Brassica cover crops used as soil amendments for managing Phytophthora blight of squash. RESULTS: In greenhouse studies, disease incidence on squash plants was significantly reduced by soil amendment with mustard shoots or roots used at 1 and 2.5% (plant tissue/soil, w/w). The shoots of canola used at 1 or 2.5% also suppressed disease, while the roots of canola or other crops did not reduce disease significantly. In field studies, soil amendments with mustard and canola provided the greatest disease reduction and increased squash yield significantly compared with the non‐treated control. Mustard and canola did not appear to be susceptible to P. capsici. CONCLUSION: The results indicated that some Brassica crops, particularly mustard and canola, had the potential to significantly reduce Phytophthora blight on squash when used as soil amendments. As P. capsici has a remarkable ability to develop resistance to chemical fungicides, use of effective Brassica cover crops could be a biorational alternative to fungicides and a valuable component in developing integrated disease management programs. Copyright © 2011 Society of Chemical Industry  相似文献   

Antifeedant activity of Jatropha gossypifolia and Melia azedarach senescent leaf extracts on Spodoptera frugiperda (Lepidoptera: Noctuidae) and their potential use as synergists     

Bullangpoti V  Wajnberg E  Audant P  Feyereisen R 《Pest management science》2012,68(9):1255-1264

BACKGROUND: To reduce rates of synthetic insecticide applications, natural product alternatives and synergists are needed. A study has been made of the toxicity of ethanolic senescent leaf extracts (SLEs) of Jatropha gossypifolia and Melia azedarach on larvae of the noctuid pest Spodoptera frugiperda. Their effects as syngergists and inhibitors of several enzyme activities are also reported. RESULTS: When added to the diet, M. azedarach SLE showed lower toxicity than J. gossypifolia SLE. However, after 2 weeks on the diet, the M. azedarach SLE proved to be lethal to 100% of the larval population. Artificial diets with both SLEs have an antifeedant effect on armyworm larvae. Acute toxicity after topical application in a dipping assay was relatively low for both J. gossypifolia and M. azedarach SLEs (LC₅₀ of 2.6 and 1.4 g L^?1, respectively, after 24 h). However, mixtures of the SLEs of M. azedarach and J. gossypifolia had a strong synergistic effect with cypermethrin. Synergism was higher with the J. gossypifolia SLE, perhaps because it contains several natural products with a methylenedioxyphenyl moiety. Both extracts inhibited P450, general esterase and acetylcholinesterase activities in vitro and in vivo. CONCLUSION: Both J. gossypifolia and M. azedarach SLEs are antifeedants to armyworm larvae when present in the food, and also have a synergistic effect with cypermethrin in topical assays. Although the synergistic effect is less than with piperonyl butoxide, both SLEs have some inhibitor activity against detoxification enzymes and acetylcholinesterase. Thus J. gossypifolia and M. azedarach SLEs may be considered as ecofriendly approaches for the control of S. frugiperda in order to reduce cypermethrin usage. Copyright © 2012 Society of Chemical Industry  相似文献   

Ecdysteroid receptor docking suggests that dibenzoylhydrazine-based insecticides are devoid of any deleterious effect on the parasitic wasp Psyttalia concolor (Hym. Braconidae)     

Bengochea P  Christiaens O  Amor F  Viñuela E  Rougé P  Medina P  Smagghe G 《Pest management science》2012,68(7):976-985

BACKGROUND: The moulting accelerating compounds (MACs) or ecdysteroid agonists represent a selective group of insecticides acting upon binding to the ecdysteroid receptor (EcR) and leading to lethal premature moulting in larval stages and aborted reproduction in adults. Psyttalia concolor Szèpl. is a useful parasitic wasp attacking important tephritid pests such as the medfly and olive fruit fly. RESULTS: Contact and oral exposure in the laboratory of female parasitic wasps to the dibenzoylhydrazine‐based methoxyfenozide, tebufenozide and RH‐5849 did not provoke negative effects. No mortality and no reduction in beneficial capacity were observed. The ligand‐binding domain (LBD) of the EcR of P. concolor was sequenced, and a homology protein model was constructed which confirmed a cavity structure with 12 α‐helices, harbouring the natural insect moulting hormone 20‐hydroxyecdysone. However, a steric clash occurred for the MAC insecticides owing to a restricted extent of the ligand‐binding cavity of the PcLBD‐EcR, while they did dock well in that of susceptible insects. CONCLUSIONS: The insect toxicity assays demonstrated that MACs are selective for P. concolor. The modelling/docking experiments are indications that these insecticides do not bind with the LBD‐EcR of P. concolor and support the theory that they show no biological effects in the parasitic wasp. These data may help in explaining the compatible use of MACs together with parasitic wasps in IPM programmes. Copyright © 2012 Society of Chemical Industry  相似文献   

水利工程管理中价值工程的应用     

任海新 《北京农业》2012,(27):153

一般会把水利工程项目实施过程中所涉及的质量管理和成本管理当作是两个不同的学科。价值工程是一门现代管理学学科,通过产品功能的分析,找出在保证产品质量的前提下节约生产资本的方法。本文主要对价值工程在水利工程管理中的应用进行探讨。  相似文献   

环道试验条件下稠油O/W乳状液的性质     

孟江  任连城  魏小林  张燕 《油气储运》2012,31(3):167-170,247,248

利用试验环道对胜利新滩含水65%稠油的W/O乳状液采用转相乳化法形成O/W乳状液的性质进行测试。3种不同方案的试验结果表明:在相同条件下,环道试验配制的乳状液液滴尺寸分布范围大,稳定性较差;在其他条件不变时,环道流量和乳化剂加量对乳状液的动态稳定性影响较大;流量越大,O/W乳状液的动态稳定性越好;在一定范围内,乳化剂加量越大,O/W乳状液稳定性越好。在管流条件下,形成O/W乳状液和乳化剂在管壁吸附均可降低管输摩阻,乳状液的稳定性是影响管道压降的主要因素。温度变化对O/W乳状液的表观粘度影响不大,同时,加剂0.8mg/g形成的O/W乳状液停输再启动不存在困难。  相似文献   

不同水肥对猩红栎轻基质容器苗生长的影响     

胡丁猛  臧真荣  王开芳  王翠香  任飞  吴德军  尹国良 《山东农业科学》2012,44(12):54-56

对1年生猩红栎轻基质容器苗进行不同的水肥处理试验,结果表明,A1B2组合(浇水1天1次,施肥0.2 g/株)处理时,猩红栎轻基质容器苗质量最好;水分为猩红栎容器苗生长的重要因子。  相似文献