Insecticide concentration for ultra-low volume crop spray application

Factors affecting the choice of optimum concentration of active ingredient of insecticides used in crop protection sprays are discussed with reference to ultra-low volume applications against cotton bollworms in Central Africa.     

Insecticide application and insect control using a drip irrigation delivery system

The effect of pesticide delivery on the eficacy of equivalent rates of several insecticides was investigated by comparing broadcast foliar sprays to applications via drip irrigation in bell peppers, celery and cantaloupe. Oxamyl applied through the drip line controlled green peach aphids, Myzus persicae (Sulzer) in bell peppers, Capsicum annum L. ‘Tambel-2’, throughout the growing season, but did not control pepper weevil, Anthonomus eugenii Cano populations. Foliar applications of oxamyl controlled both insects. Foliar applications of cyromazine controlled leafminers, Liriomyza spp. in bell peppers late in the growing season. Drip applications of cyromazine suppressed leafiminers early in the growing season, but were ineffective in later applications. In cantaloupe, Cucumis melo L. ‘Magnum 45’, populations of melon aphids, Aphis gossypii Glover were suppressed with oxamyl and oxydemeton-methyl, but foliar applications were significantlymore effective in achieving reductions. Oxamyl controlled leafmminers in cantaloupe with both application methods after the first evaluation, but control was superior with foliar applications at the second evaluation. Oxamyl suppressed populations of the western potato leafhopper, Empoasca abrupta DeLong in celery, Apium graveolens L. ‘5270’, using either delivery method. Oxamyl residues in drip-applied celery were higher than USA regulations would allow, thus the rate of application would have to be modified. A cost analysis comparing delivery systems indicated that a drip-applied insecticide application was much less expensive than a foliar application with air or ground equipment. However, control was limited to phloem-feeding insects, was slower in attainment, and at best, was equal to or less than that obtained with a foliar spray.     

Chlorpyrifos degradation in soil at termiticidal application rates

Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] is an organophosphorus insecticide applied to soil to control pests both in agricultural and in urban developments. Typical agricultural soil applications (0.56 to 5.6 kg ha^?1) result in initial soil surface residues of 0.3 to 32 μg g^?1. In contrast, termiticidal soil barrier treatments, a common urban use pattern, often result in initial soil residues of 1000 μg g^?1 or greater. The purpose of the present investigation was to understand better the degradation of chlorpyrifos in soil at termiticidal application rates and factors affecting its behaviour. Therefore, studies with [¹⁴C]chlorpyrifos were conducted under a variety of conditions in the laboratory. Initially, the degradation of chlorpyrifos at 1000 μg g^?1 initial concentration was examined in five different soils from termite-infested regions (Arizona, Florida, Hawaii, Texas) under standard conditions (25°C, field moisture capacity, darkness). Degradation half-lives in these soils ranged from 175 to 1576 days. The major metabolite formed in chlorpyrifos-treated soils was 3,5,6-trichloro-2-pyrid-inol, which represented up to 61% of applied radiocarbon after 13 months of incubation. Minor quantities of [¹⁴C]carbon dioxide (< 5%) and soil-bound residues (? 12%) were also present at that time. Subsequently, a factorial experiment examining chlorpyrifos degradation as affected by initial concentration (10, 100, 1000 μg g^?1), soil moisture (field moisture capacity, 1.5 MPa, air dry), and temperature 15, 25, 35°C) was conducted in the two soils which had displayed the most (Texas) and least (Florida) rapid rates of degradation. Chlorpyrifos degradation was significantly retarded at the 1000 μg g^?1 rate as compared to the 10 μg g^?1 rate. Temperature also had a dramatic effect on degradation rate, which approximately doubled with each 10°C increase in temperature. Results suggest that the extended (3–24 + years) termiticidal efficacy of chlorpyrifos observed in the field may be due both to the high initial concentrations employed (termite LC ₅₀ = 0.2– 2 μg g^?1) and the extended persistence which results from employment of these rates. The study also highlights the importance of investigating the behaviour of a pesticide under the diversity of agricultural and urban use scenarios in which it is employed.     

病毒杀虫剂产品中多角体的染色计数方法

本文介绍了一种直接检测病毒杀虫剂产品中多角体数量的染色计数方法。该染色计数法测得的多角体数量要低于血球计数板的计数结果,但变异系数较血球计数板计数法显著较小,结果稳定,适用于病毒杀虫剂的质量检测。     

棉花害虫抗药性治理

棉蚜、棉铃虫、棉红铃虫是棉田上最重要的害虫 ,长期以来主要依靠化学农药进行防治。由于大量连续单一使用农药 ,致使害虫对多种农药产生了抗药性 ,一些高效农药的防治效果大大降低 ,在有些高抗地区 ,部分农药甚至完全失去了防治作用。因此 ,棉花害虫抗药性的治理显得尤为重要 ,这就要求我们要加大综合防治的力度 ,注重科学用药 ,通过实施轮换、交替、混合、用药及加增效剂等措施 ,达到降低棉田抗性害虫数量 ,延缓害虫抗药性发生的目的。1　运用栽培措施压低虫源基数随着棉花栽培制度的变革和栽培技术的提高 ,运用农事操作达到压低虫口基数 …     

Some Hydrolases and Their Involvement in Insecticide Resistance

Abstract

Virus diseases are an important factor worldwide in crop production losses. Correct diagnosis of a disease is essential and in developing countries in the absence of modern facilities virologists regard infectivity tests as an important tool in identifying viruses. However compared with progress in other areas of plant virology infectivity assays lag behind. These tests should be carried out under optimum environmental conditions to permit symptom development. Environmental conditions should be standardised. Results of infectivity tests should be interpreted in relation to variation in the environment and the use of a known cultivar and its source. The use of an indicator host relates indirectly with variation in the environment and consequently symptom development. A suitable host must be used if the virus is to initiate infection. Plants used as indicator hosts must be genetically identical and from the same origin. Sensitive hosts are required to index seed batches in a well organised seed certification programme. There is a need for international seed and serum centres in strategic regions among developing countries and close collaboration between virologists to list genetically identical test plants for infectivity assays under their own conditions. Other factors to improve identification include an understanding of insect vectors. When used properly these tests can play a significant role in identification of virus strains and screening for resistance against virus diseases of economically important cash and food crops.     

Dissipation of cyproconazole and quinalphos on/in grapes

The persistence of cyproconazole and quinalphos on/in grapes was investigated when both compounds were applied to vines at the locally recommended application frequencies and rates and at double these rates, using commercially available formulations. Residues of cyproconazole applied at recommended and double the recommended rates of application in/on grapes immediately after the last application were 0-049 (±0.034) and 0.077 (±0.008) mg kg^?1, respectively, reduced to 0.011 (±0.003) and 0.018 (±0.010) mg kg^?1 respectively seven days after the last application. The corresponding residue levels of quinalphos immediately following the last application were 1.42 (±0.10) and 3.36 (±0.07) mg kg^?1, reduced to 0.043 (±0.002) and 0.072 (±0.028) mg kg^?1 respectively 21 days after the last application. Cyproconazole, being systemic, is rapidly absorbed by the grape tissues and its residues dissipate with a half-life of three to four days, while quinalphos, being non-systemic, dissipates faster with a half-life of two or three days. The residues of both pesticides were analysed by a GLC-NPD system.     

Reduced efficacy and enhanced degradation of carbetamide after repeated application in Australia

Following reports of poor weed control, the effectiveness of repeated applications of carbetamide atid propyzamide in controlling Lolium rigidum Gaud, (annual ryegrass) was examined under field conditions. Repeated applications of carbetamide or propyzamide were less effective in controlling L. rigidum than an initial application. A single application of carbetamide or propyzamide was sufficient approximately to halve the efficacy of a subsequent treatment with the satne herbicide. Laboratory incubations of soil linked the poor performance of carbetamide upon repeated application to an enhanced deg-radation rate. We conclude that the repeated application of carbetamide or propyzamide results in less effective weed control under field conditions and that this can be partially avoided by rotation between carhetamide and propyzamide.     

戊唑醇在葡萄和土壤中的残留和消解动态

建立了葡萄中戊唑醇残留的气相色谱测定方法,并研究了其在葡萄和土壤中的消解动态。土壤用乙腈提取,无需净化,葡萄样品用甲醇提取,二氯甲烷液液分配净化后用气相色谱-氮磷检测器(GC-NPD)测定。结果表明:在 0.01、0.1、1 mg/kg 3个添加水平下,戊唑醇的平均回收率为85.0%~98.8%,相对标准偏差(RSD)为2.9%~10.4%;最小检出量为1×10-11g,最低检测浓度为0.01 mg/kg。采用250 g/L戊唑醇水乳剂按有效成分187.5 mg/L剂量(推荐剂量的1.5倍)施药,戊唑醇在葡萄中的半衰期为9.8~12.2 d,在土壤中的半衰期为8.2~17.3 d,药后28、35 d葡萄中的最终残留量≤0.81 mg/kg,低于国际食品法典委员会(CAC)和中国规定的最大残留限量2.0 mg/kg。建议在葡萄上使用250 g/L戊唑醇水乳剂时,施药剂量最高为有效成分187.5 mg/L,施药2~3次,采收间隔期为28 d。     

三种叶面肥在新疆两种葡萄上应用效果的比较研究

研究了3种叶面肥对红地球葡萄和木纳格葡萄产量和品质的影响。结果表明,在葡萄不同生育时期喷施螯合氨基酸钙液肥、腐植酸液肥和平衡营养肥,均明显增加了2个葡萄品种叶片叶绿素SPAD值、产量、可溶性固形物含量和还原型Vc含量,显著降低可滴定酸含量。其中红地球葡萄和木纳格葡萄,以连续喷施4次螯合氨基酸钙液肥效果最好:每公顷产量增幅分别为8.50%和17.15%,明显高于其它两喷肥处理,品质也好于其它两喷肥处理。     

Enhanced degradation in soil of tri-allate and other carbamate pesticides following application of tri-allate

Tri-allate degraded faster in soil from a site (T1) that had received 1·7 kg ha^?1 of tri-allate annually for 23 years than in soil from an adjacent site (TO) that had received no pesticide application. Soil from the untreated site, which had been removed to a glasshouse and treated three times per annum with tri-allate at 1·7 kg ha^?1 for 7 years (T2), also showed faster degradation. Soil previously treated with tri-allate showed an increased degradation rate for carbofuran and EPTC but not for aldicarb. A further experiment, 2 years after the last treatment with tri-allate, showed that the enhanced degradation effect was still present. Degradation rates were always in the order T1 > T2 > T0 for tri-allate, EPTC and carbofuran. Half-life for degradation was reduced for tri-allate and carbofuran by approximately 40% in the previously treated soils and for EPTC by approximately 80% when compared with the previously untreated soil.     

Relationship between azinphos-methyl usage and residues on grapes and in wine in Australia

Azinphos-methyl was applied to Shiraz winegrapes by commercial high-volume and hand-held sprayers during seasons 1993/94 and 1994/95. Residue levels in grapes resulting from treatments applied by commercial sprayer were below the maximum residue level (MRL) of 2 mg kg^-1 for grapes in Australia, whereas residues resulting from treatments applied by hand-held sprayer still exceeded the MRL five weeks after final application. There was a strong correlation for most treatments between treatment concentration of azinphos-methyl and residue level in grapes, and in wine made from treated grapes. Applied at the recommended rate (1·2 g litre^-1 wettable powder (WP) and 2·4 ml litre^-1 suspension concentrate (SC)) by commercial high-volume sprayer, azinphos-methyl residue levels in wine were well below the MRL, and below the MRLs of most importing countries, except Denmark and Sweden. When applied by hand-held sprayer, residue levels in wine were 5·9–29·6 fold higher than those previously obtained by commercial application of insecticide. Since wines are often blends from different grape blocks and grape-growing districts, in practice, this is unlikely to be of concern. Wine made from grapes treated by commercial sprayer showed no detectable residues of azinphos-methyl after one year of storage. In both years, residue levels in grapes of both formulations of azinphos-methyl fluctuated during the five-week post-treatment period, although there was an overall downward trend. Previously unrecorded systemicity in azinphos-methyl was demonstrated in laboratory studies with barley seedlings, and this may explain these fluctuating data in grapes. The reduction of azinphos-methyl residues in grapes over time appears to be a complex phenomenon involving translocation of active ingredient combined with an increase in the size and weight of berries, producing fluctuating residue levels. © 1998 SCI     

干旱风沙灌漠土玉米田树脂包衣尿素施用效果研究

田间试验对比研究了树脂包衣尿素和普通尿素在灌漠土和风沙土两种土壤上种植玉米的肥料投入产出效益和产量差异。结果表明:树脂包衣尿素在灌漠土和风沙土两种土壤的玉米产量效应上均有良好的表现,与等氮量的普通尿素相比,灌漠土玉米增产6.4%,风沙土玉米增产15.4%。而在灌漠土和风沙土上分别施用是常规氮肥用量50%和67%的包衣尿素,则可获得与普通尿素相等的产量。灌漠土上施用树脂包衣尿素的经济效益好于普通尿素。风沙土上施用等氮量包衣尿素时,经济效益最好,施用67%包衣尿素时,经济效益略低。灌漠土与风沙土两个试验点比较,风沙土试验点不但施氮量比灌漠土高出127.5 kg/hm2,而且其产量还略低于灌漠土试验点。     

不同种群螟黄赤眼蜂和松毛虫赤眼蜂的抗药性测定

分别测定了螟黄赤眼蜂和松毛虫赤眼蜂各5个不同地理种群对灭多威、溴氰菊酯、辛硫磷的室内抗性水平。结果表明,不同地区或不同生态条件下的赤眼蜂种群具有抗药性差异。螟黄赤眼蜂的敏感种群为采自吉林省长春市的农场种群,与之比较,其他4个种群对灭多威的LC50的变化范围为其1.93～6.72倍,对溴氰菊酯的LC50为其5.35～39.08倍,对辛硫磷的LC50为其3.49～29.76倍;松毛虫赤眼蜂的敏感种群为采自黑龙江省尚志市的亚布力南种群,与之比较,其他各个种群对灭多威的LC50的变化范围为其9.52～70.66倍,对溴氰菊酯的LC50为其73.12～288.16倍,对辛硫磷的LC50的变化范围为11.84～50.38倍。     

防治葡萄白粉病新型杀菌剂的筛选及增效剂的增效作用

为了筛选防治葡萄白粉病的绿色高效新型药剂和适宜的增效剂,以达到减量增效防病的目的,本研究选用10种杀菌剂对葡萄白粉病进行田间药效试验,同时评价5种增效剂对杀菌剂的减量增效作用。结果表明,20%氟唑菌酰羟胺·苯醚甲环唑悬浮剂和29%吡萘·嘧菌酯悬浮剂效果最好,对葡萄白粉病的防效分别为75.75%、63. 80%。在推荐剂量下Silwet 636、Silwet 806、Y-20079、杰效利等4种增效剂对29%吡萘·嘧菌酯悬浮剂具有明显的增效作用,当减少30%药剂使用量或减少30%药液量时添加这4种增效剂的处理防效均优于单一药剂处理,其中Silwet 636表现最佳。推荐施用20%氟唑菌酰羟胺·苯醚甲环唑悬浮剂1 500倍液和29%吡萘·嘧菌酯悬浮剂2 000倍液田间防治葡萄白粉病。在减30%药剂量或药液量条件下,在29%吡萘·嘧菌酯悬浮剂中添加Silwet 636、Silwet 806、Y-20079、杰效利等增效剂也可达到同等或更优防效。