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931.
932.
Titers of two systemic neonicotinoid insecticides in citrus trees were measured in conjunction with conventional evaluations of their impact on glassy-winged sharpshooter (Homalodisca coagulata (Say); GWSS) populations. Xylem fluid samples were collected at regular intervals and from multiple locations within field-grown citrus trees to determine imidacloprid and thiamethoxam concentrations using commercial ELISA kits. Uptake profiles varied considerably with peak mean titers of imidacloprid occurring 6-8 weeks after application compared with 2 weeks for thiamethoxam. The persistence of each compound also varied as near-peak levels of imidacloprid were sustained for another 6-10 weeks before gradually declining. In contrast, thiamethoxam titers declined more rapidly after the initial peak, possibly reflecting an application rate only one-quarter of that used for imidacloprid. Within-tree distributions were more similar for the two compounds, with no significant effect due to height of the sample (upper or lower half) or to the quadrant location within the tree, with the exception of one quadrant in the thiamethoxam-treated trees. Substantial reductions in GWSS nymphs and adults were observed in imidacloprid-treated trees during the 2001 trial and were sustained for 4-5 months after treatment. Treatment effects on nymphs were not as well pronounced in the 2002 trial, when overall GWSS infestations were much reduced from the previous year. However, consistently lower adult infestations were still observed in 2002 for both treatments compared with untreated trees. Information on the spatial and temporal profiles in citrus trees was obtained for both compounds to complement field impact data and improve understanding of their pest management potential. 相似文献
933.
为明确多种新型作用机制杀菌剂与引起梨树褐斑病、黑星病、白粉病等病原菌的有效对靶关系及制定梨树主要病害防治流程,采用菌丝生长速率法、离体叶片法与田间药效方法研究新型杀菌剂对靶标病原菌的毒力、对靶标病害的防效及其田间有效应用,建立替代梨树主要病害传统化学杀菌剂的防治流程技术。结果显示,双胍三辛烷基苯磺酸盐在离体叶片法下对褐斑病的防效大于85%,田间药效验证3次用药后7 d防效大于85%、30 d防效大于80%、90 d防效仍大于60%,兼治轮纹病菌其毒力EC50值均小于1 μg·mL-1。双胍三辛烷基苯磺酸盐、辛菌胺醋酸盐、吩嗪α-2羧酸在离体叶片法下对黑星病防效大于90%且毒力EC50值小于1 μg·mL-1;田间药效验证1次用药后7 d防效大于80%、30 d防效仍大于75%。噻肟菌酯、硝苯菌酯、丙硫菌唑在离体叶片法下对白粉病的防效大于85%;田间药效验证3次用药后7 d铲除效果大于70%、30 d仍大于60%。丙硫菌唑对黑斑、轮纹病菌毒力EC50值均小于1 μg·mL-1;吩嗪α-2羧酸同时对褐斑、黑斑、轮纹病菌毒力EC50值小于1 μg·mL-1。针对梨树主要病害发生期,选用新型杀菌剂替代传统杀菌剂制定防治技术流程,其综合防效达到88.94%。不同新型作用机制杀菌剂在防治梨树主要病害上的应用,能够降低抗药性产生,同时达到有效防治的目的。 相似文献
934.
对巨峰葡萄落花落果的严重问题进行化学调控试验,结果表明:在花前4~10天喷布500~5000ppm浓度的B_9药剂能明显提高巨峰葡萄座果率,其中以3000ppm浓度的效果最为显著。而硼砂和多效唑也有很好的效果,均可提高巨峰葡萄座果率。 相似文献
935.
本文记述了采自辽宁省本溪县的隆侧姬峰属一新种,辽宁隆侧姬蜂Latibulusliaonigensis,sp.n..并指出了它和近似种:东方隆侧姬蜂L.orientalisHorstmann的主要区别特征. 相似文献
936.
跗线螨属一新种(螨目 跗线螨科) 总被引:3,自引:0,他引:3
本文描述跗线螨属一新种,新种Tarsonemus kropf与T.schlechtendali Suski1966很相似,但其Ta毛生于表皮内突Ⅰ上或紧靠其下;3b毛生于表皮内突Ⅳ的下端;背面e毛长于f毛;前中表皮内突与表皮内突Ⅱ相接。模式标本分别存放于甘肃农业大学植保系和德国联邦农林生物研究中心葡萄保护研究所。 相似文献
937.
938.
939.
Plant health is a frequently used but ill‐defined term. However, there is an extensive literature on general health definitions and health criteria in human medicine. Taking up ideas from these philosophical debates, concepts of plant health are reviewed and a framework developed to locate these concepts according to their position in several philosophical controversies. In particular, (i) the role of values in defining plant health in a naturalist versus a normativist approach; (ii) negative and positive definitions of plant health; (iii) reductionist versus holistic perspectives; (iv) the focus on functionality versus resilience, i.e. the ability of the plant to perform under stress with or without human interference; (v) materialist versus vitalist approaches; and (vi) biocentric versus anthropocentric views, are surveyed. The ways in which these perspectives relate to mainstream and alternative approaches to plant protection are explored and we suggest how the contradicting views might be reconciled. It is argued that none of these perspectives is without inherent contradictions, but that by combining contrasting approaches it is possible to provide a comprehensive though fuzzy concept. Rather than giving a new definition of plant health, a conceptual framework is developed that suggests what questions may be answered in debates on plant health issues and how such debates could be organized. 相似文献
940.
本文将数据包络分析中的CCR模型应用于农作物病虫防治效果的综合评价.该方法通过比较各种防治措施的投入和产出,确定一种成本最低,综合效果最好的防治策略.本文以各种防治措施对苹果果园病虫害进行防治的模拟数据为例,详细介绍了CCR模型在病虫综合防治评价中的应用.结果表明,CCR模型对各种防治措施进行综合评价时具有多输入和多输出且不依赖权重调整的优势,评价结果客观、易用. 相似文献