Pesticide residues on the external surfaces of field-crop sprayers: environmental impact

There is increased awareness of the need to clean the external surfaces of sprayers, but the extent to which the washings may impact on the environment is not known. Quantification of the levels of external residues on sprayers could give an indication of the potential environmental impact of sprayer cleaning. The presence of azoxystrobin, carbendazim, chlorothalonil, cyanazine, cypermethrin, epoxiconazole, flusilazole, isoproturon, kresoxim-methyl, metazachlor, pendimethalin, pirimicarb and tebuconazole on thirteen sprayers, sampled on two occasions was investigated. Composite samples were taken from the boom, nozzles and spray tank (delivery system) and the mudguard, cab door, rear window and windscreen (tractor body). Despite being subject to some form of cleaning, pesticides were detected on all sprayers. Residues were found at higher quantities and with greater frequency on the nozzles and booms, but the mean dose on the spray tank was equal to that on the mudguard (7.2 mg m(-2)). Isoproturon, pendimethalin, metazachlor, chlorothalonil and azoxystrobin were all detected above 1000 mg m(-2) on the delivery system, whereas on the tractor body the highest concentrations were between 100 and 1000 mg m(-2) (isoproturon, pendimethalin, chlorothalonil and carbendazim). On the whole, azoxystrobin was detected on the least number of occasions. However, there was great variation within and between compounds and sampling sites. Generally sprayers were not cleaned frequently or efficiently, enabling residues to accumulate on the external surfaces where they can remain for years. The findings here indicate that the quantity of these residues may be sufficient to be harmful to aquatic organisms should the residues enter a watercourse. In addition, if all the residues were removed by cleaning in the field and the washings catchment area was 15 m2 or less, overdosing could occur. Further work is required to assess whether a more frequent cleaning regime would reduce the overall environmental impact of cleaning sprayers. Implications for potential occupational exposure are considered elsewhere.     

Use of models to assess the reduction in contamination of water bodies by agricultural pesticides through the implementation of policy instruments: A case study of the Voluntary Initiative in the UK

Through normal agricultural use, pesticides may reach environmental water bodies via several routes of entry. Various policies and initiatives exist to reduce the effects of pesticides in the environment. One such initiative in place in the UK is the Voluntary Initiative (VI). The VI is a voluntary scheme put forward by the Crop Protection Association with other crop protection and farming organisations to reduce the environmental impacts of pesticides. Mathematical models of pesticide fate can usefully be applied to examine the impact of factors influencing the contamination of water bodies by pesticides. The work reported here used water quality models to examine how changes in farmer behaviour could potentially impact pesticide contamination of environmental water bodies. As far as possible, uncalibrated, standard regulatory models were used. Where suitable models were not available, simple models were defined for the purposes of the study and calibrated using literature data. Scenarios were developed to represent different standards of practice with respect to pesticide user behaviour. The development of these scenarios was guided by the Crop Protection Management Plan (CPMP) aspect of the VI. A framework for the use of modelling in the evaluation of the VI is proposed. The results of the modelling study suggest that, in several areas, widespread adoption of the measures proposed in the VI could lead to reductions in pesticide contamination of environmental water bodies. These areas include pesticide contamination from farmyards, spray drift and field runoff. In other areas (including pesticide leaching to groundwater and contamination of surface water from field drains) the benefits that may potentially be gained from the VI are less clear. A framework to evaluate the VI should take into consideration the following aspects: (1) groundwater is more at risk when there is a combination of leachable compounds, vulnerable soils, shallow groundwater and high product usage; (2) surface water contamination from drains is most likely when heavy rain falls soon after application, the soils are vulnerable and product usage is high; (3) surface water contamination from drift is most likely when the distance between the spray boom and water body is small and product usage is high; (4) surface water contamination from farmyards is dependent on the nature of the farmyard surface, the competence of the spray operator and the level of product usage. Any policy or initiative to reduce pesticide contamination should be measured against farmer behaviour in these areas.     

多旋翼植保无人机喷施新烟碱类杀虫剂对蜜蜂的飘移风险

为明确植保无人机喷施新烟碱类杀虫剂对非靶标生物蜜蜂的飘移风险,在田间试验场景下,比较分析多旋翼植保无人机和背负式电动喷雾器喷施新烟碱类杀虫剂时的雾滴飘移量及对蜜蜂的影响。结果表明：应用背负式电动喷雾器和多旋翼植保无人机进行施药作业时,距离施药区下风向5 m处的雾滴飘移率分别为0.50%和23.98%;而多旋翼植保无人机施药时,即使距离施药区下风向17 m处的雾滴飘移率仍高达2.79%,且多旋翼植保无人机施药时的飘移总量显著高于背负式电动喷雾器。喷施新烟碱类杀虫剂时,应用背负式电动喷雾器作业时距离下风向5 m处的蜜蜂在施药后1 d内的死亡数量为75头,分别是距离下风向17 m处和对照组的2.4倍和1.8倍,施药后2~8 d内蜜蜂的死亡数量与对照组无明显差异;应用多旋翼植保无人机作业时距离下风向5 m处的蜜蜂在施药后1 d内的死亡数量为4 721头,分别是距离下风向17 m、29 m处和对照组的3.0倍、6.1倍和112.4倍,施药后2~8 d内蜜蜂的死亡数量明显降低,但距离施药区较近的蜜蜂其死亡数量明显高于对照组,表明多旋翼植保无人机喷施新烟碱类杀虫剂对蜜蜂存在较高的飘移风险。     

三种苗前除草剂对茅苍术杂草防治效果及安全性评价

为了筛选出防效好、残留少且对环境影响较小的茅苍术苗前除草剂,选取常用的3种苗前除草剂乙草胺、乙氧氟草醚和二甲戊灵,研究其除草效果,对叶绿素荧光参数的影响,农药残留情况及其对土壤微生物真菌和细菌群落的影响。结果表明,乙草胺的除草效果较好,株防效和鲜重防效都达到了80%以上,对茅苍术叶绿素荧光参数影响较小,农残较少,对土壤细菌和真菌群落无显著性影响;乙氧氟草醚和二甲戊灵对叶绿素荧光参数有影响,短时间内有一定的土壤农残。综合防效和安全性,优选乙草胺作为茅苍术的苗前除草剂。     

Small-scale vegetable producers’ perception of pests and pesticide uses in East Shewa zone,Ethiopia

Vegetable growers’ knowledge of pest and their control method was assessed in 2014 in East Shewa zone, Ethiopia. Vegetable growers were well aware of key pests of vegetables, although some of them did not consider pests as constraint to vegetable production. All respondents scouted their vegetables for pests and used presence or absence of pest as criterion for spraying. About 76% of the respondents read pesticide label before buying pesticides, while the rest 24% of the respondents did not read pesticide labels. All vegetable growers sprayed insecticide, whereas fungicides and herbicides were applied by 90% and 7% of the respondents, respectively. About 72% of the respondents washed their sprayer after each application day and discharged the washings onto the soil. Moreover, the majority (62%) of the respondents threw empty pesticide containers around the field. Also, it was found that 71% of the respondents did not use personal protective equipment (PPE) while spraying pesticides, but a few used one or two types of PPE. More than half of the respondents sprayed pesticides on mature crops and sold the produce within three to five days.     

不同植保器械在水稻不同生育期喷施农药的沉积率及雾滴参数

评估不同植保器械的农药喷施效率为水稻上农药减量控害和统防统治工作提供理论技术支撑.本研究参照NY/T 2677—2015《农药沉积率测定方法》,在广东省南雄市全安镇晚造直播水稻田开展农药喷施试验,分析了分别采用手动喷雾器、电动喷雾器和植保无人飞机喷施的农药沉积率及雾滴参数.结果表明:在同一水稻生育期使用不同植保器械喷施...     

小麦间作豌豆和挥发物释放结合不同器械施药对麦田害虫和天敌的影响

利用作物间作和挥发物释放的农田害虫生态调控“推-拉”技术，可以增加田间生物多样性，提高天敌的控害效果，减少农药使用。然而，为了实现害虫防控的农药减施增效目的，不同施药器械施药结合生态调控技术对害虫和天敌种群动态以及作物产量的影响研究较少。本研究采用新型自走式喷雾机和传统手动背负式喷雾器两种施药器械，分别对单作小麦、小麦豌豆间作、小麦豌豆间作＋蚜虫报警激素反式-β-法尼烯（EBF），以及小麦豌豆间作＋水杨酸甲酯（MeSA）等处理下施用杀虫和杀螨剂，系统调查分析四种处理对小麦产量、小麦蚜虫、红蜘蛛，以及相关天敌发生量的影响。结果显示，自走式喷雾机的施药速度显著高于手动背负式喷雾机。不同施药器械防治小麦害虫可以显著影响小麦的穗粒数和产量。自走式喷雾机施药的间作＋MeSA处理的小麦千粒重和产量明显高于其他处理。在单作田中，两种施药器械对荻草谷网蚜和瓢虫平均发生量无显著影响，自走式喷雾机施药处理的禾谷缢管蚜、红蜘蛛和天敌僵蚜的发生量显著降低。自走式喷雾机施药的间作＋MeSA田的荻草谷网蚜、禾谷缢管蚜和红蜘蛛的发生量明显低于其他处理，而瓢虫的发生量显著高于其他处理。两种药械施药情况下，间作＋MeSA田小麦上僵蚜量均明显高于单作田。两种施药器械施药前，单作和间作＋MeSA田红蜘蛛发生量较低；施药后间作＋MeSA处理的小麦红蜘蛛密度一直维持比较低的水平；间作＋EBF和间作＋MeSA的两个处理在喷药后第二次调查才达到红蜘蛛数量低峰，而同期的单作处理红蜘蛛发生数量有明显回升。总之，小麦间作＋MeSA处理可以显著增加小麦产量，对于麦田小麦蚜虫和红蜘蛛的防控效果和对天敌的吸引保护效果最好。对麦田喷药效率、对害虫防控效果和增加小麦产量综合评价，自走式喷雾机具有明显优势。然而，需要注意的是对比传统手动喷雾器喷药可能对天敌寄生蜂有更强的非靶标作用。     

多旋翼植保无人飞机水稻飞防中的农药飘移和施药人员暴露

为研究多旋翼植保无人飞机施药时农药雾滴飘移规律以及施药作业人员职业暴露情况，依据喷雾飘移田间测试国际标准ISO22866和人体暴露贴片测试法，对多旋翼植保无人飞机和电动背负式喷雾器在水稻田喷施氯虫苯甲酰胺和苯醚甲环唑时的农药雾滴飘移量及施药作业人员人体农药沉积量进行了对比测试和分析评价。结果表明:在本试验环境条件下，多旋翼植保无人飞机在作业速率4 m/s和作业高度1.8 m参数下施药时，在距施药区下风向边界0~30 m范围内地面均有农药飘移性沉积，30 m处氯虫苯甲酰胺飘移率为0.9%，而背负式喷雾器施药的飘移量则主要集中在距施药区0~3 m区域内，3 m以外区域飘移率均≤0.6%；背负式喷雾器在距施药区5 m以及10 m远处空中不同高度的飘移量均小于0.001 μg/cm2，多旋翼植保无人飞机在距施药区5 m远处空中的飘移量大于10 m处，并且在垂直分布上，距冠层2 m左右 (无人飞机的飞行高度) 处飘移量最多。结合两种施药机具的雾滴粒径(背负式喷雾器DV₅₀ 值为149.4 μm，多旋翼植保无人飞机DV₅₀ 值为115.3 μm) 分析，无人飞机的雾滴具有更高的飘移潜力。由于实现了人机分离，多旋翼植保无人飞机进行作业时人体暴露量很低，而背负式喷雾器施药时对作业人员身体各部位均会造成一定的暴露，其中以手前臂和腿部正面暴露最为严重，在施用苯醚甲环唑时，右前臂背面暴露量最高，达到15.19 μg/cm2。本文中针对多旋翼植保无人飞机喷雾作业时在下风向的飘移沉积研究方法和试验结果，以及对多旋翼植保无人飞机施药过程中职业暴露的研究，可为农药喷雾作业缓冲区距离确定和人员作业安全评估提供参考。     

Variation in pesticide hazard from vegetable production in Great Britain from 1991 to 2003

Pesticides pose a difficult problem for policy makers as society generally seeks to reduce any adverse impacts of their use, while industry claims they are important contributors to economic success. Attempts to direct policy according to scientific findings are hampered by the multidimensionality of the potential impacts of pesticides which may affect consumers, operators, wildlife and the environment. Pesticide risk indices seek to reduce these multidimensional impacts into a single dimension and have been increasingly used to understand variation in the hazard posed by pesticides at both field and regional level. This study uses one such risk index, the environmental impact quotient (EIQ), to estimate the hazard posed by pesticide usage from 1991 to 2003 on several vegetable crops grown in the UK. Results are reported for the EIQ and for the environmental impact (EI) for brassicas, peas, beans, onions, leeks, lettuce and endives. The EIQ is a dimensionless estimate of the toxicity of a product, while the EI, which combines the EIQ with data on actual usage, estimates the overall hazard of the use of a product. The exact trends in EIQ and EI varied with crop over the period 1991-2003, but overall the EIQ decreased by 19% and the EI decreased by 34%. However, the mean EI per hectare decreased by only 3%. This suggests that some of the observed reduction in EI at the national level may be related more to decrease in crop area than changes in pesticide use and management. If these observed losses in crop area are being replaced by vegetable imports from overseas, then this raises the possibility that the UK is effectively exporting any problems related to pesticide use. The ethics of this remain unclear.     

A Field Bioassay Approach to Assess the Toxicity of Insecticide Residues on Soil to Collembola

Field bioassays were conducted to assess the toxicity of three insecticides, chlorpyrifos, cypermethrin and pirimicarb, to four species of springtails, Isotoma viridis, Isotomurus palustris, Folsomia candida (Collembola: Isotomidae) and Sminthurus viridis (Collembola: Sminthuridae). Spray residues on two soil types (a sandy clay loam and a sandy soil) were obtained in the field, in the presence and absence of a wheat crop canopy, after spray application by a commercial tractor-mounted sprayer. Collembola were then confined for 24-h periods on the sprayed soils in a constant laboratory environment at 1, 2, 3, 8 and 15 days after treatment. Residual insecticide toxicity was compared between species, insecticides, soils and exposure conditions (crop or no crop) using the age of residue at which median mortality occurred (DAT₅₀). Cypermethrin and pirimicarb residues were of low toxicity, causing less than 10% mortality, whereas residues of chloryprifos were toxic to all four species of Collembola on both soil types and in both exposure treatments. Interspecific differences in collembolan susceptibility to chlorpyrifos residues gave the ranking (from most to least susceptible) S. viridis>F. candida>Isotomurus palustris>Isotoma viridis. Residues on the sandy soil were more toxic than those on the sandy clay loam. These results are discussed in terms of how field bioassay approaches may be used to determine pesticide residual toxicity to microarthropods. We conclude that field bioassays offer a feasible method for evaluating the toxicity of pesticides and the persistence of toxic effects on Collembola. Advantages and disadvantages of this method are considered.     

The Direct Injection Technique for Preparing the Spray Mix - A Method for Reducing Safety and Hygiene Problems in Plant Protection?1

In the past, industry and research institutes have produced a number of technical proposals to improve sprayer technique, and development in this area has been very successful. The «closed sprayer-system>>, the pesticide flushing system, flow regulation systems and updated stirring arrangement are examples of many different practicable improvements. A completely new approach to improving application technique is the « direct injection of pesticides >>: contrary to normal practice the tank of the sprayer is filled with pure water only. The pesticide is introduced in concentrate form into a separate tank and injected into the water flow produced by the equipment pump during the application process. The advantages of this technique include no direct handling of the active substance concentrate; no problems with liquid-stirring; no pesticide residues. A commercial sprayer equipped with a metering device prototype and a newly developed constant pressure fitting is described as an illustrative example of prospective design of a « direct-injection >> system. A number of other technical possibilities exist for putting this method into practice. The advantages of this technique have to be paid by an additional capital outlay but they offer the chance to reduce safety and hygiene problems in chemical plant protection.     

40%氯虫苯甲酰胺·噻虫嗪水分散粒剂防治二化螟田间药效试验

通过田间试验研究不同药剂对二化螟防治效果、产量及用药成本的影响。结果表明,40%氯虫苯甲酰胺·噻虫嗪水分散粒剂10 g/667m2防治晚稻二化螟的效果明显高于常规用药15%阿维·三唑磷乳油100 mL/667m2,且40%氯虫苯甲酰胺·噻虫嗪水分散粒剂10 g/667m2能起到保护生态环境,减少农药用量、降低农药残留的作用。施药方法：于第3代二化螟卵孵盛期至2龄高峰前施药,可提高防效4.98%,每667 m2减少施药工本6元,增加产量31 kg,减少用药成本11元,667 m2增加总效益79.4元。     

5%甲氨基阿维菌素苯甲酸盐乳油防治烟田烟青虫药液最佳使用方案研究

为确定烟田采用5%甲氨基阿维菌素苯甲酸盐乳油喷雾防治烟青虫时的最佳药液配制方案,本研究采用正交试验方法研究了稀释倍数、施药液量和添加Silwet喷雾助剂对烟田喷雾防治烟青虫的影响,以药液在烟田的沉积率和对烟青虫的防治效果为评价指标,结合单因素的极差分析结果,获得5%甲氨基阿维菌素苯甲酸盐乳油在烟田喷雾时的最佳配制施药方法。结果表明:在使用3WBJ-16DZ静电喷雾器喷洒5%甲氨基阿维菌素苯甲酸盐乳油防治烟青虫时,药剂稀释1 000倍(有效成分含量50mg/L)、施药液量15L/667m2、添加Silwet喷雾制剂30mL/667m2,药液在烟草植株上的沉积率高达63.76%,7d对烟青虫防治效果达到95.84%,显著好于农户采用的稀释2 500倍(有效成分20.00mg/L)、施药液量50L/667m2的防治效果(76.50%)。本文丰富了烟田喷雾时药液配制方面的参数筛选内容,为农药合理使用提供了有力的技术支持。     

农药田间药效试验工作的经验及做法

农药田间药效试验有别于一般防治示范或简单的效果观察。它是农药在进入市场之前,国家为保证农药对有害生物的防治效果和对作物及环境的安全性而开展的一项重要工作。农药田间药效试验需要对农药产品防治效果、负面效应以及环境影响作出客观、公正的综合评价,为农药生产企业办理农药登记提供资料,为农药推广应用提供科学依据。为保证农药田间药效试验的准确性和对试验药剂进行客观合理的分析、评价,笔者通过多年的实践经历,总结了做好农药田间药效试验经验以及具体做法。     

Production of <Emphasis Type="Italic">Guignardia bidwellii</Emphasis> conidia on grape leaf lesions is influenced by repeated washing events and by alternation of dry and wet periods

The ascomycete Guignardia bidwellii is an economically important pathogen in many grapevine-growing areas. Primary infections are caused by ascospores and conidia produced in mummified berries and in cane lesions. Secondary infections are caused by the conidia produced by pycnidia formed in leaf lesions and, in later season, in rotted berries. Environment-controlled experiments were conducted to study the production dynamics of G. bidwellii conidia on grape leaf lesions as influenced by: i) repeated washing events, and ii) alternate dry and wet periods. Under optimal environmental conditions (25 °C, 100 % relative humidity), production of conidia declined over washings and was almost completely depleted after four washings. When pycnidia were kept in a low humidity environment (average of 54 % relative humidity) between two successive washings, the production of conidia progressively diminished as the time between washings increased, with few conidia being still produced after 87 days. This decline in conidial production was faster at 29 °C than at 20 °C. This information is relevant in that it determines the potential of black-rot lesions to produce conidia along the grape-growing season and, therefore, their contribution to epidemic development.     

Organochlorine pesticide residues in soils from six U.S. Air Force bases, 1975--76.

Soil samples collected during 1975 and 1976 from United States Air Force installations in California, Georgia, Ohio, Oklahoma, Texas, and Utah were analyzed for organochlorine pesticide residues. Sigma DDT, chlordane, and dieldrin were the pesticides most commonly found. In 1975, sigma DDT residues were significantly higher in samples from residential areas than in samples from golf courses or areas free of pesticide application. Chlordane residues in 1975 were significantly higher in both residential and golf course areas than in areas where pesticides had not been used. No significant differences were found in 1976 in residue levels of any pesticide monitored among various land use areas.     

臭氧去除果蔬中农药残留研究进展

水果、蔬菜中农药残留的清洗去除研究是进一步提升食品安全的保证。臭氧处理技术是去除农药残留的常用方法之一。本文主要介绍了用于去除水果蔬菜上农药残留的臭氧处理技术,包括:臭氧产生方式、应用形式以及臭氧与其他方法联合处理技术的应用,综述了影响农药残留去除效果的因素,也介绍了臭氧去除农药残留的同时对果蔬外观、营养等影响,进一步探究了臭氧去除农药残留的作用机制和应用价值,旨在为臭氧清洗技术用于去除果蔬农药残留的研究提供理论和应用参考。     

喷雾参数对自走式喷杆喷雾机稻田喷雾农药利用率及雾滴沉积分布的影响

比较在不同喷雾压力和施药液量条件下,采用自走式喷杆喷雾机在水稻分蘖期、孕穗期、扬花期进行喷雾处理的农药利用率、沉积分布均匀性及水稻茎基部雾滴密度的差异,为建立自走式喷杆喷雾机在稻田的高效施药技术提供理论依据。以生物染料丽春红-G作为农药示踪剂,估测不同喷雾参数的农药利用率,并用变异系数、绝对份额比例值比较农药分布的均匀性。同时通过水敏纸收集水稻基部雾滴密度,分析不同喷雾参数下农药雾滴穿透水稻冠层的能力。结果表明:在水稻分蘖期,采用自走式喷杆喷雾机在喷雾压力为1.2 MPa、施药液量为375 L/hm^2条件下喷雾,每个采样点的丽春红-G的平均沉积量仅为0.11 mg,与喷雾压力为0.4 MPa、施药液量为300 L/hm^2条件下喷雾的沉积量相比减少了56.00%。在水稻孕穗期,当喷雾压力为1.2 MPa、施药液量为375 L/hm^2时进行喷雾处理,每个采样点的丽春红-G的平均沉积量达0.26 mg,显著高于其他4个处理。在水稻扬花期,不同喷雾参数间的沉积量差距减小。在合适的喷雾压力和施药液量时,自走式喷杆喷雾机在水稻分蘖期、孕穗期和扬花期进行喷雾处理,农药利用率分别达到40.57%、54.97%和55.50%。综合变异系数和绝对份额比例两个指标,采用自走式喷杆喷雾机在喷雾压力为0.8 MPa、施药液量为300 L/hm^2条件下喷雾,农药分布更均匀。喷雾压力对水稻基部雾滴密度有显著影响,在水稻生长中后期,当喷雾压力低于0.8 MPa、施药液量为225~375 L/hm^2时,水稻茎秆基部雾滴密度均小于30个/cm^2。研究结果表明,喷雾压力和施药液量对自走式喷杆喷雾机稻田喷雾的农药利用率、分布均匀性及水稻茎秆基部雾滴密度有显著影响。在水稻生长前期,不宜采用高压力大水量喷雾作业;在水稻生长中后期,为增加对水稻基部病虫害的防治效果,需提高喷雾压力。     

江苏溧阳水稻田减量用药研究初探

为尽可能减少稻田农药的使用量,更好地保障稻米品质及保护农田生态环境,通过优化药剂组合和施药次序,综合田间防效、消解动态、最终残留及水稻产量等因素,研究评估了江苏省溧阳市水稻田农药减量施用的可行性。分别设置常规施药组合和减量施药组合2套方案,以水稻主要病虫害稻飞虱、稻纵卷叶螟及纹枯病为例,比较了2种施药方案下对病虫害的防效,分析了相关药剂在水稻中的残留消解动态以及在稻米和谷壳中的最终残留,并对水稻产量进行了考察。结果表明:减量施药方案对水稻上3种典型病虫害的防效均优于或与常规施药方案相当;此外,不同施药次序对水稻病虫害的防治效果差异较大;2种施药方案下,供试药剂在稻米中的最终残留量均未超过其残留限量 (MRL) 标准;与常规施药方案相比,减量施药方案下水稻每公顷产量增加了621 kg,但二者差异不显著。减量方案施用农药总制剂量为4 410 g/hm2 (有效成分1 353 g/hm2), 而常规方案为6 885 g/hm2 (有效成分1 553 g/hm2)。研究表明,在试验期间,该减量施药方案能有效防控水稻病虫害,保证水稻产量,同时还能减少环境中农药及助剂的投入,降低对环境的危害。     

A Portable Sprayer for Treating Experimental Plots

Abstract

The construction and operation of a portable light-weight spray boom and accompanying backpack are described. The sprayer can be used to apply pesticides accurately to experimental plots 3 or 4 m wide and is operated by two people. For lightness, both the main framework of the boom, to which the nozzles are attached, and the supporting struts are constructed of aluminium. The pesticide spray is supplied to the boom from a backpack consisting of a stainless steel tank (either 6 or 12 l capacity) and a high pressure gas cylinder. This sprayer has been found to be suitable for application of pesticides to plots larger than those normally treated with most small plot sprayers, but smaller than those requiring vehicle-mounted machines. An appendix lists the suppliers of the parts used and their cost.