Spray deposit cover and fungicide distribution obtained by low and ultralow volume spraying of intensive apple trees

Spray deposit assessments were made on the leaf surfaces in the top, middle and base zones of intensively grown dessert apple trees sprayed by a conventional high volume automatic mast method applying 2250 litres/ha, an experimental low and ulfralow volume tractor mist blower, applying 225 litres/ha at normal dilution, 45 litres/ha at five times normal concentration or 22.5 litres/ha at ten times normal concentration, and a modified proprietary hand-directed fan-disc sprayer applying 225 or 22.5 litres/ha. Fluorescent tracer assessments showed that the high volume method gave heavy cover on upper and lower surfaces of the leaves in all zones, the tractor mist method gave lighter but uniform cover and the fan-disc sprayer gave sparse cover on the upper surfaces at the top and on the lower surfaces at the base zone. The hand-directed low and ultralow volume methods, applying one-tenth of the amounts of copper fungicide/ha, gave deposit levels 5–30 % of those of the high volume method and the tractor mist applications gave 0.8–5.2%. The corresponding captan deposits from 5–6 applications were 12–50% and 10–20%: residual deposits from the ultralow volume applications of the concentrated captan were greater than the low volume applications of the same quantities in dilute form. In general, the order of pest and disease control obtained by the three methods was high volume automatic, fan-disc and experimental mist, and this was related to the order of deposit levels: the order of control by the three volume rates was 2250, 225 and 22.5 litres/ha, and this could be related to the degree of spray cover.     

Assessing the efficiencies of low and high volume methods of applying pesticides to tobacco

Low volume carbendazim sprays (25–100 litre/ha) applied with a knapsack mistblower fitted with twin nozzles or a mesh diffuser were compared with high volume sprays (760 litre/ha) from three pairs of ‘Spraying Systems’ Y6 nozzles on the vertical boom of a knapsack pressure sprayer. The carbendazim concentration and total amount deposited were measured by thin-layer chromatography and bioassay. The twin nozzles, which directed two spray streams 50° apart, deposited most fungicide on the plants using 100 litre/ha, and in two experiments 76 and 80% of theoretical amounts applied per plant were detected in or on the leaves. At 25 litre/ha, the distribution was less uniform and the deposit efficiency was 74%. The mesh diffuser at 100 litre/ha was less efficient; where the spray was directed between and parallel to the rows of tobacco the deposits were 26 and 42% of the total carbendazim applied, whereas directing the spray at an angle of about 45° towards the rows of tobacco increased the deposit to 57%. Sprays applied at a pressure of 410 kPa (4.1 bar) from Y6 nozzles deposited only 16% of the active ingredient onto the leaves. Better control of powdery mildew caused by Erysiphe cichoracearum was obtained with dinocap using the mesh diffuser than with either the Y6 nozzles or with dusts from a motorised duster.     

Pedestrian sprayers: equipment for ultra-low and very-low volume spraying1

Plant protection products often need to be applied to small areas, inaccessible to vehicular equipment, hence the need for manually carried equipment. While there are lever-operated knapsack and compression sprayers using conventional hydraulic nozzles, reduced-volume applications have been developed in combination with the use of rotary atomizers to provide a narrow droplet spectrum. Most of the initial development of these hand-carried battery-operated spinning disc sprayers was for their use in the semi-arid tropics to apply insecticides to cotton in the absence of plentiful water supplies. This continues to be the main market for these sprayers, although the trend recently has been away from oil-based ultra-low volume formulations to very-low volume spraying (typically 5-1 5 litre ha¹) of water-based formulations to reduce costs and allow greater flexibility in choice of insecticide in integrated pest management programmes. Changes in equipment design have been made to suit this change in spray volume and formulation. Air-assisted sprayers have also been used in glasshouses. Subsequent development of rotary atomizers operated at slower speeds has led to the equipment being used for herbicide application. especially in forestry and urban situations where low weight of equipment and drift reduction have been important considerations. Formulations prepacked in containers to connect directly to the sprayers have been used to reduce operator contamination.     

New trends in orchard spraying1

Since the early part of the century, a steady move in England towards lower volume spraying of orchards has coincided with the progressive introduction of improved spraying techniques. In recent years many growers have adopted very low volume (VLV) spraying (50 litre ha^-1) using spinning-disc nozzles with greatly reduced dose rates, often only 25% of the product label recommendation. On well managed farms, this method of spraying has been successful for several years and considerable savings have been made in pesticide use and labour for spraying. On other farms there have been pest and disease control problems but few growers have reverted to spraying at conventional volume or pesticide rates. Trials evidence from the UK and the Netherlands shows the VLV reduced dose-rate spraying technique to be generally less effective than conventional spraying but usually sufficiently effective for commercial purposes. In the Netherlands a compromise method of low volume spraying (150–200 litre ha^-1) is being adopted on the recommendation of research and advisory services. This method of spraying is gaining popularity in England. Unfortunately, the method of application stipulated on product labels is usually restricted to a minimum water volume and a pesticide dose per ha. It might be desirable for experimental work for registration purposes to be done to explore optimum application methods for individual pesticides. This information on labels, in a simple form, might lead to the more efficient use of pesticides as well as reflecting the range of application methods in use in the industry.     

The influence of the extensional viscosity of very low concentrations of high molecular mass water-soluble polymers on atomisation and droplet impact

BACKGROUND: Water-soluble polymers are increasingly added to herbicide and pesticide formulations at very low concentrations (100-1000 mg L(-1)) in order to control the spray characteristics, notably to reduce spray drift and influence droplet bounce. The incorporation of polymeric adjuvants improves the efficacy of the spray solutions, thus enabling crop growers to maximise the performance of agrochemical sprays at lower dose rates of active ingredient. It is important to establish a fundamental understanding of how polymers influence the processes involved in droplet deposition.RESULTS: The shear and extensional viscosities of a series of high molecular mass (M(w)) poly(acrylamides) (M(w) approximately 10(6)-10(7)) have been determined at very low concentrations (100-1000 mg L(-1)). The polymer solutions demonstrated typical shear thinning characteristics under shear, and strain hardening behaviour under extension above a critical strain rate. The presence of the polymers was shown to increase the size of droplets produced in atomisation using an agricultural spray nozzle, as measured by laser diffraction. This was attributed to the increase in the extensional viscosity at the strain rates generated under pressure in the spray nozzle and was a function of both polymer concentration and M(w). In addition, the presence of polymer was found to have a significant influence on droplet bounce.CONCLUSIONS: The presence of very low concentrations of high molecular mass poly(acrylamides) significantly influences the size of droplets formed on atomisation and subsequent bounce characteristics. Large extensional viscosities generated above a critical strain rate are responsible for both processes.     

Interception and persistence of parathion and fenvalerate on cotton plants as a function of application method

Parathion (O,O-diethyl O-4-nitrophenyl phosphorothioate) and fenvalerate [(RS)-α-cyano-3-phenoxybenzyl (RS)-2-(4-chlorophenyl)-3-methylbutyrate] were applied by controlled droplet applicators (CDAs) and conventional hydraulic nozzles in refined soybean oil, soybean oil + water, or water, to mature cotton plants (Gossypium hirsutum L.) as ULV (ultra-low volume, < 5 litre ha^?1), VLV(very low volume, 5-50 litre ha^?1), or LV(low volume, 50–200 litre ha^?1) carrier rates. The use of CDA or soybean oil applied as ULV and VLV sprays did not produce greater deposition or persistence for either insecticide during the 49-h test period following application. In general, insecticide persistence was greatest when applied with water or soybean oil + water as LV sprays using the conventional TX8 hydraulic nozzle.     

机动弥雾法施用70%吡虫啉水分散粒剂防治小麦蚜虫的雾滴沉积密度与防效的关系

田间采用背负式机动弥雾机对70%吡虫啉水分散粒剂进行喷雾试验,证明若吡虫啉喷雾雾滴在小麦穗部形成一定的沉积密度即可有效防治麦蚜。当70%吡虫啉水分散粒剂用水稀释2 333倍(有效成分300 mg/L),雾滴密度在54,133和280个/cm2条件下,施药7 d后对麦蚜的防治效果分别为83.3% ,88.7%和93.7%;当药剂稀释1 167倍(有效成分600 mg/L),雾滴密度在75,142和291个/cm2条件下,7 d后对麦蚜的防治效果分别为88.1%,94.5%和96.5%。采用背负式机动弥雾机,采用常量150 L/hm2、低浓度(300 mg/L)喷雾时,小麦穗部、旗叶上的雾滴沉积密度分别为177±12,113±8个/cm2,沉积量分别为27.4±6.8,6.6±1.6 ng/cm2,地面流失率为12.8%,7 d后的防治效果为94.0%; 当采用低容量75 L/hm2、高浓度(600 mg/L)喷雾时,小麦穗部、旗叶上的雾滴沉积密度分别为127±13,91±7个/cm2,沉积量分别为29.8±1.2, 6.7±0.6 ng/cm2,地面流失率为10.6%,7 d后的防治效果为93.8%。生产中建议采用吡虫啉低容量75 L/hm2、高浓度600 mg/L喷雾,省工、省水、省时。     

Glasshouse trials with controlled drop application of some foliage-applied herbicides

MCPA, mecoprop, dichlorprop, dicamba, 2,3,6-TBA, bentazone, ioxynil/bromoxynil (a mixture), barban, difenzoquat and chlorfenprop-methyl were applied by spinning disc in controlled drop sizes from 150-350μm and at very low volume rates (5–45 1/ha), to the foliage of some dicotyledonous weed species or wild oats (Avena fatua L.). The same herbicides were also applied by means of conventional hydraulic nozzles at volume rates of about 200 1/ha. Most of these herbicides performed as well at very low volume rates as with the conventional application, the major exceptions being bentazone, ioxynil/bromoxynil (both of which have distinct contact effects) and dichlorprop. Comparisons between oil and water as the diluent at a very low volume rates suggest that there may be situations when oil is preferable and others when water is.     

杀螟松防治麦蚜的研究

1983—1986年通过室内毒力测定比较,在20种供试农药中筛选出杀螟松对麦蚜具有很高毒力,田间试验和示范表明,小麦不同部位农药沉积量同药效呈正相关,杀螟松对小麦各部位的蚜虫均有良好防效。1985—1986年在京、冀、甘、川、豫等省示范和推广10多万亩,每亩用50％乳油30毫升,无论用高容量、低容量、超低容量或吹雾法喷雾,防效均在90％以上。杀螟松是我国正在发展的大吨位农药品种,具有防效好、药源广、成本低、对人畜安全、无残毒等优点。作者认为是值得推荐的防治麦蚜的农药品种。     

Deposition and Biological Efficacy of Electrostatically Charged and Uncharged Sprays in Cereal Crops1

Cereal crops were sprayed with conventional hydraulic nozzles (2501/ha), electrostatic hydraulic nozzles (66 l/ha), spinning discs (aqueous 5 l/ha and oil 2 l/ha) and ICI « Electrodyn >> nozzles (1 and 2 l/ha). The ULV sprays were applied with or without air assistance. An experimental triazole fungicide was applied with fluorescent tracer and control of RhynchospoHum secalis in barley and Erysiphe graminis in wheat was compared with deposit data. The two high volume spray systems performed well with no significant differences in disease control or deposition between charged and uncharged modes at 66 l/ha. The spinning disc and « Electrodyn >> systems performed well with air assistance but, without air, deposition was uneven and disease control inferior. The «Electrodyn>> system often produced the largest total deposits but, without air, assistance spray deposition was concentrated mainly in the upper plant parts. The results indicate that under suitable conditions application volumes as low as 1 l/ha can be as effective biologically as high volumes when the same amount of fungicide per hectare is used. Relationships between spray distribution within cereals and sites for pest and disease attack are discussed with regard to different methods of application.     

Weed Problems in Chotanagpur Agriculture

Abstract

Micron Sprayers Ltd have produced a sprayer, the Herbi, designed to produce uniform atomisation with both oil- and water-based formulations. Three different nozzle sizes give low, medium and high flow rates. In performance tests wetting agents were found to be necessary to produce uniform droplets. The volume distribution across the swath showed four peaks and for the flow rate, liquid and atomiser height examined the two major peaks were at 50 and 60 cms either side of the line of the sprayer, indicating a peak to peak width of 110 cm. Of the collected spray, 75% settled within a central band of 120 cm, 99% within 180 cm and 100% within 195 cm. To prevent superimposition of peaks leading to high overdose, a swath width of 150–160 cm is suggested, such that overlap occurs at the outer position of half peak height. To avoid excessive spray drift it is recommended that the sprayer is not used in any but very light wind. The authors conclude that this machine should prove very useful for very low volume application between rows in bush and tree crops, and for treating larger areas.     

Distribution and activity of spray deposits in an oak canopy following aerial application of diluted and undiluted formulations of Bacillus thuringiensis Berliner against the gypsy moth,Lymantria dispar L. (Lepidoptera: Lymantriidae)

The distribution and biological activity of spray deposits resulting from aerial applications of diluted and undiluted Bacillus thuringiensis, ‘Dipel 64AF’ against the gypsy moth, Lymantria dispar L., were examined in oak stands in south-eastern Ontario, Canada. The sprays were applied by fixed-wing aircraft equipped with four ‘Micronair AU4000’ atomizers. Application of diluted formulation at 30 BIU ha^?1 in 6.0–6.4 litre generally resulted in a higher droplet density (10–28 cm ^?2 leaf) than application of undiluted product at the same dosage rate in 1.8 litre ha^?1 (4–10 cm ^?2). However, spray deposits of undiluted product with a volume median diameter (D_v.5) of 90–130 μm caused as much mortality of gypsy moth larvae in bioassays of sprayed foliage as deposits of diluted product with a D_v.5 of 150–350 μm despite a two- to three-fold reduction in droplet density. Our data suggest that by using fine spray atomization, undiluted application of these formulations can offer the same efficacy against gypsy moth as coarsely atomized sprays of diluted product.     

Effect of the Volume Rate of Application on the Glasshouse Performance of Crop Protection Agent/Adjuvant Combinations

The effects of volume rate of application on the glasshouse performance of three recently developed crop protection agent/adjuvant combinations are discussed. High volume rates of application on easy-to-wet foliage, such as potato (Solanum tuberosum, L.) caused reduction of the adjuvant-enhanced performance of dimethomorph seen at low volume rates. These reductions were largely attributable to relatively lower spray retention with spray drop coalescence and run-off being observed, particularly at the higher adjuvant rates. On difficult-to-wet foliage (wheat, Triticum aestivum, L.; oat, Avena sativa, L.) two different effects were seen. With a metconazole formulation/‘Dobanol’ 91-6 combination on wheat, no systematic changes in performance were observed with change in volume rate. With a flamprop-M-isopropyl formulation/‘Dobanol’ 25-7 combination, statistically significant increases in performance were seen with increasing volume rate. In both cases the observations can be explained as the result of a combination of interacting factors involving spray pattern, spray deposition and, by inference, foliar uptake of the crop protection agent, the proportions of which differed between the two cases. It is suggested that the effect of volume rate of application on performance of adjuvant-containing formulations is investigated on easy-to-wet foliage to determine the upper limits and on difficult-to-wet foliage to determine any variation in performance that may occur. Such information will guide the design of field trials and may aid interpretation of field results.     

植保无人机施药沉积飘移监测系统设计与应用

为提升植保无人机施药沉积飘移监测智能化水平,研发植保无人机施药沉积飘移监测系统,该系统机载监测终端实时获取药械状态参数、植保无人机状态参数及位置参数,通过数据处理服务系统将其发送至平台软件,基于作业参数利用沉积飘移预测模型实时监测药液沉积区域及飘移范围。该系统同时具有作业面积计量、飞行轨迹回溯、作业质量空间分析等功能。2015年4月于山东省威海市文登区泽头镇眠虎岭区域对该系统进行性能测试,植保无人机规划靶区作业面积为433 hm²,最终监测作业面积为405 hm²,施药覆盖率为93.5%;施药过程中实时监测沉积区域和飘移范围,受环境侧风影响,药液最大飘移距离可达40 m,系统整体达到预期设计要求。截至目前该系统已在山东、安徽、江苏、云南、河南、浙江、天津等多个省市应用。     

Efficacy and fate of glyphosate on Swedish railway embankments

The herbicide glyphosate, N-(phosphonomethyl)glycine, as Spectra (240 g AI litre(-1) SL; Monsanto Europe AB), RoundUp (360 g AI litre(-1) SL; Monsanto) and RoundUp Bio (360 g AI litre(-1) SL; Monsanto), have been used for weed control on Swedish railway embankments since 1986. This article summarizes results from studies of the weed effect and behaviour of glyphosate for the period 1984-2003. Studies on a railway embankment with a range of application rates showed excellent weed control at 5 litre ha(-1) of RoundUp Bio. The appearance of glyphosate and its metabolite AMPA [(aminomethyl)phosphonic acid] in the embankment, eg mobility and persistence, was also studied. Mobility was low in most cases, the main proportion of both glyphosate and AMPA being found in the upper 30-cm layer although minor amounts penetrated to lower depths. The 50% disappearance time of glyphosate was generally <5 months in railway embankments but cases with longer persistence were found. Transport to the groundwater was observed for glyphosate and AMPA in groundwater pipes along tracks. Downward transport appears to be dependent on the application rate, which should not exceed 3 litre ha(-1) of RoundUp Bio to avoid groundwater contamination. A lower rate of glyphosate mixed with a low rate of another herbicide may achieve acceptable weed control and be environmentally safer.     

Influence of formulation properties on droplet size spectra and ground deposits of aerially-applied pesticides

The influence of the physical properties of the spray liquid on droplet size spectra and ground deposits of aerially-applied pesticides was studied using heavy (high-viscosity) oil- and water-based suspensions of wettable powders (w.p.), a clear solution in a light (low-viscosity) oil, and an emulsion-suspension containing a bacterial control agent. The heavy oil provided a highly viscous spray medium, 52 to 64 mPa s (at a shear rate of 480 s^?1), resulting in large droplet sizes and a high deposit on the ground sampling units. When the spray medium was thickened with petroleum jelly to keep the w.p. in suspension during overnight storage, the viscosity became excessively high (102 mPa s at 480 s^?1), and the droplet spectrum was undesirably coarse and resulted in poor coverage of the spray plot and low deposits. The light-oil-based solution (ca 4 mPa s), provided a finer droplet spectrum and lower deposits than the heavy-oil-based formulations. The water-based suspensions of the w.p. (ca 2 mPa s), showed Newtonian behaviour, whereas the emulsion-suspension (ca 240 mPa s at 480 s^?1) showed pseudoplastic behaviour. Consequently, the emulsion-suspension provided a markedly different droplet spectrum from that of the suspensions of the w.p. Nevertheless, all three aqueous media provided deposits comparable to those of the light-oil-based solution, markedly lower than the heavy-oil-based suspensions. The study indicated that highly viscous Newtonian formulations should be avoided in pesticide applications using Micronair AU3000 atomisers at the volume rate (4–7 litre ha^?1) used here if high atomisation efficiency is required.     

The effect on earthworm populations of methods of spraying benomyl in an apple orchard

Compared with high volume (2240 litre/ha) sprays, low (560 litre/ha) and ultra-low volume (45 litre/ha) sprays of benomyl were less toxic to earthworms. The decrease in populations was proportional to the quantity of fungicide deposited on the ground; regression lines, probit (% reduction) on log (fall out in g/ha), are given for populations of Lumbricus terrestris and all species together. The reduction in numbers was similar for all species except L. terrestris and Allolobophora longa, L. terrestris was more susceptible to the deposits than the other species; A. longa was less affected, probably because it was in summer diapause.     

Retention of iprodione on salad onion leaves in relation to the control of Botrytis spp.

Using bioassay and fluorescent tracer techniques it was demonstrated that more fungicide was retained on mature leaves of summer salad onion crops if 1 kg/ha iprodione wettable powder (w.p.) formulation plus wetting agent was sprayed at 280 1/ha than at 560 1/ha or 1120 1/ha.
The lowest spray volume (280 1/ha) with four sprays of iprodione w.p. (0.5 kg in October, November, December and January) gave effective control of Botrytis cinerea and significantly increased plant stand and yield. More fungicide was required to obtain equivalent results using a mixed programme of two thiram (4 kg/ha total) and two iprodione w.p. (2 kg a.i./ha total) sprays at the same application volume and intervals. Where the mixed programme was applied at 1 1 20 1/ha, 1 2 kg a.i. (total fungicide) was necessary to achieve equivalent disease control.
At 280 1/ha, retention and persistence of iprodione on onion foliage was greater with the oil-based than with the wettable powder formulation. In summer especially this resulted in improved Botrytis control and greater numbers of marketable onions. In winter onions, oil and w.p. formulations were equally effective and gave equivalent improvements in plant stand and yield.     

Penetration of bean leaves by aminotriazole as influenced by adjuvants and humidity

Penetration of bean leaves (Phaseolus vulgaris var. Canadian Wonder) by aminotriazole (3-amino-1,2,4-triazole) was greatly enhanced under high humidity conditions (ca 10% in 17 h at the low humidity level (LHL) compared with ca 80% in 2 h at the high humidity level (HHL)). The addition of polyoxyethylene 20 sorbitan monolaurate (polysorbate 20) to the spray fluid increased penetration on all occasions at the LHL. The increase obtained was found to be dependent on the concentration of polysorbate 20. The inclusion of polysorbate 20 at the HHL resulted in an increase in aminotriazole penetration at low polysorbate 20 concentrations 0.2–12.8 g/litre and a non-significant decrease over the aqueous control at a concentration of 40 g/litre. With additions of glycerol to the spray fluid, aminotriazole penetration was increased on all occasions at the LHL while at the HHL no concentration of glycerol was found to enhance penetration. The addition of polysorbate 20 (< 0.1 to 40 g/litre) to a spray solution containing glycerol (0.3 ml/litre) enhanced penetration at the HHL compared with the aqueous and glycerol controls. A polysorbate 20 plus glycerol combination (6.4 g+0.6 ml/litre) gave the same order of penetration (98.4 and 94.0%) at the HHL and LHL respectively. In both cases penetration exceeded that obtained with the corresponding polysorbate 20 and glycerol controls. Some of the practical implications of these findings are discussed.     

Green nanoemulsion‐laden glyphosate isopropylamine formulation in suppressing creeping foxglove (A. gangetica), slender button weed (D. ocimifolia) and buffalo grass (P. conjugatum)

BACKGROUND: Pesticides are developed with carriers to improve their physicochemical properties and, accordingly, the bioefficacy of the applied formulation. For foliar‐applied herbicide, generally less than 0.1% of the active ingredient reaching the target site could reduce pesticide performance. Recently, a carrier of nanoemulsion consisting of oil, surfactant and water, with a particle size of less than 200 nm, has been shown to enhance drug permeability for skin penetration in pharmaceutical delivery systems. In the present work, the aim was to formulate a water‐soluble herbicide, glyphosate isopropylamine (IPA), using a green nanoemulsion system for a biological activity study against the weeds creeping foxglove, slender button weed and buffalo grass. RESULTS: The nanoemulsion formulations displayed a significantly lower spray deposition on creeping foxglove (2.9–3.5 ng cm^?2), slender button weed (2.6–2.9 ng cm^?2) and buffalo grass (1.8–2.4 ng cm^?2) than Roundup^® (3.7–5.1 ng cm^?2). The visible injury rates of weeds treated with the nanoemulsion formulations were statistically equivalent to those relating to Roundup^® at 14 days after treatment, with a control range of 86.67–96.67%. CONCLUSION: It was hypothesised that the significant difference in spray deposition with equal injury rates can be attributed to enhanced bioactivity of the nanoemulsion formulations. This initial discovery could be the platform for developing better penetration of agrochemical formulations in the future. Copyright © 2012 Society of Chemical Industry