Conventional Flat-fan Nozzles Research Articles

Motion model for describing the quantity of air in droplets through changing the structure of air induction nozzle

Air induction nozzles possess good anti-drift performance, the throat and orifice sizes of the nozzles are main design parameters that affecting atomization. Therefore, Venturi tube nozzles and conventional flat fan nozzles were assembled together to investigate the flow rate, droplet size, the quantity of air in droplets affected by single design parameter of nozzles with applying high speed camera and Spraytec laser diffraction system. The results showed that: the flow rate of the air induction nozzle depended only on the throat size of Venturi tube and pressure, and it was proportional to the throat size of Venturi tube at the same pressure; The flat fan nozzle’s orifice size and Venturi tube size significantly affected volume median diameter of droplets, which generally increased after adding surfactant; A new model was established after optimizing classical equation for calculating the percentage of intake air in droplets and studying the effects of throat and orifice size of air induction nozzles on spray characteristics. By variance analysis, it was verified that the new model of quantity of air in droplets produced by all connected nozzles was correct. The calculation showed that the bubbles sizes ranged at 200-900 μm and were in proportion to the droplet size with the percentage of intake air of 10% to 90%. Contrast to the change of volume median diameter and droplet velocity, existence of intake air could influence their change degree to some extent. Keywords: throat orifice, spray characteristic, model of droplet motion, air induction nozzle DOI: 10.25165/j.ijabe.20211405.5513 Citation: Hu J, Liu C X, Wang Z C, Li Y F, Song J L, Liu Y J, et al. Motion model for describing the quantity of air in droplets through changing the structure of air induction nozzle. Int J Agric & Biol Eng, 2021; 14(5): 35–40.

On-Farm Evaluation of Nozzle Types for Peanut Pest Management Using Commercial Sprayers

ABSTRACT Growers have rapidly adopted auxin-resistant cotton and soybean technologies. In Georgia, growers who plant auxin-resistant cotton/soybean are required to utilize nozzles that produce larger (coarser) droplets when spraying auxin herbicides to minimize potential off-target movement of pesticides. Consequently, these nozzles are also used in peanut (an important rotational crop with cotton) since changing nozzles between crops is uncommon for growers. However, larger droplets can result in reduced spray coverage which may lead to less effective pest control. Therefore, seven on-farm trials were conducted in commercial peanut fields using commercial sprayers from 2018 to 2020 across four different locations in Georgia to compare the spray performance of air-induction (AI) nozzles that produce very coarse to ultra coarse droplets (VMD50 ≥ 404 microns) with non-AI (conventional flat fan) nozzles that produce medium to coarse droplets (403≥VMD50≥236 microns) for pest management in peanuts. For each trial, test treatments were implemented in large replicated strips where each strip represented a nozzle type. For nozzle comparison, XR and XRC represented non-AI nozzles while TADF, TDXL, TTI, and TTI60 represented the commonly used AI nozzles in these trials. Spray deposition data for each nozzle along with disease ratings, weed and insect control ratings were collected in all on-farm trials. Peanut yield was collected at harvest. Results indicated that the AI nozzles produced larger droplets than the non-AI nozzles in all nozzle tests; however, the spray coverage varied among the nozzle types. Nozzle type did not influence pest (weed, disease and insect) control, or peanut yield (p>0.10) in any of the on-farm trials. These results suggested that peanut growers can utilize these coarser droplet nozzles for pest management in fields with low to average pest pressure during the season. Future research on nozzle evaluation needs to investigate the influence of droplet size, carrier volume, and pressure on coverage and canopy penetration.

Effect of adjuvant types and concentration on spray drift potential of different nozzles

Pesticide exposure via spray drift can have a negative impact on bystanders, residents, livestock, terrestrial and aquatic ecosystems. Reducing pesticide spray drift and maximizing efficacy are the paramount considerations when selecting technologies and operating parameters prior to making an application. With the increasing awareness about the potential risk of pesticides, many mitigation measures for pesticide exposure via spray drift have been developed. The effect of spray adjuvant and pesticide formulations is not yet well evaluated and implemented into drift mitigation scenarios. It is often stated that drift reduction with an appropriate nozzle is greater than those achieved by formulated products or spray adjuvant. In fact, to explore the combined effect of nozzle type and physical properties of spray liquids is also important. In order to study effect of adjuvant on spray drift potential of different nozzles, we used wind tunnel, and spectrofluorophotometor to carry out experiment which focused on how concentration of anti-evaporation adjuvant Agrospred 730AS-2, anti-drift adjuvant Break-thru Vibrant, Silwet DRS-60 and Greenwet 360 were affected by Drift Potential Index (DIX) of conventional flat fan nozzle Lechler ST 110-015, hollow cone nozzle TR 80-015, reference nozzle Lumark F110-03 and rotary nozzle. It has been reported in literature that the amount of spray drift is usually related to the percentage of fine spray droplets. The smaller a spray droplet, the longer it remains as airborne and the higher the possibility for it to be carried away by crosswind. Moreover, spray droplets of a few microns in size can evaporate before sedimentation. Therefore, it is fundamentally important to measure droplet size and the size distribution to understand the environmental and the biological fate of spray droplets. In this article, Malvern particle sizer was used to test Volume Median Diameter (VMD) and the percentage of droplets with diameter 75 μm of the four nozzles above. The concentration of AS-2 solution was 0, 0.005 %, 0.05 %, 0.5 %, the concentration of Break—thru Vibrant solution was 0, 0.1%, 0.2%, 0.4 %, the concentration of Silwet DRS-60 solution was 0, 0.1%, 0.2%, 0.4%,0.8% and the concentration of Greenwet 360 solution was 0, 0.3% respectively. In the test, Pyranine 120% (0.01%) tracers were used to test and analyze the spray drift potential. The results showed that: when spraying 0.05% solution with anti-evaporation adjuvant AS-2, DIX of rotary nozzle (6 000 r/s, 400 mL/min) increased 81.8%, VMD increased 16.7% compared with water under the condition of which wind speed was 1.8 m/s, temperature was 30oC, humility was 40% in the wind tunnel. With the concentration of 0.8%, 0.4% and 0.3%, respectively, anti-drift adjuvant Silwet DRS-60, Break-thru Vibrant and Greenwet 360 can significantly reduce the spray drift. Especially for TR 80-015, DIX decreased 98.7%, 58.2% and 80.1% separately with the adjuvant above compared with water. The drift reduction performance of three hydraulic nozzles was TR80-015>ST110-015>Lumark F110-03 under the condition of which wind speed was 2 m/s, temperature was 20, humility was 80 % in the wind tunnel. For rotary nozzle, DIX decreased 70.3 % and 26.0 % with 0.8% Silwet and 0.3 % Greenwet 360 separately, while Break—thru Vibrant had no effect on it. For Silwet DRS-60 and Greenwet 360, DIX increased as the volume percentage of droplets with diameter 75 μm increased which showed positive correlation (the correlation coefficient R>0.5);DIX decreased as VMD increased which showed negative correlation, so VMD and volume percentage of droplets with diameter 75 μm were considered to be important factors affecting drift potential.

Determination of drift potential of different flat fan nozzles on a boom sprayer using a test bench

This study's objective was to evaluate the functionality of an ad hoc test bench for spray drift measurement with boom sprayers, using it for evaluating different nozzles according to drift risk. The repeatability of results was evaluated by conducting similar tests at two different laboratories. Drift potential values (DPV) obtained showed an interesting effect of Venturi flat fan nozzles on drift reduction, in comparison with conventional flat fan nozzles (reference nozzle was XR 11003). Newly designed flat fan nozzles reduced the risk of drift. Reasonably relations between 10th-percentile, D[v,0.1], 50th-percentile or Volume Median Diameter, D[v,0.5], 90th-percentile, D[v,0.9], V100 and DPV were observed in all cases, with R2 values of 0.58, 0.65, 0.66 and 0.72, respectively. The lowest drift values were achieved with TTI and TD Spray Max nozzles; they were significantly lower than those obtained for IDK and AIXR ones. Results indicated that the drift test bench can be used as an alternative to the official standard procedure for drift measurements on boom sprayers (e.g. ISO 22866), as it is able to discriminate the influence of different boom settings (especially nozzle types) on drift. Further studies could be useful in order to prove that the classification of nozzles according to drift risk obtained using the test bench is comparable to the nozzle classifications obtained applying the ISO 22866 test method.

CHARACTERIZATION OF HYDRAULIC NOZZLES FOR DROPLET SIZE AND SPRAY COVERAGE

Spray coverage specifications for commercially available nozzles could help applicators determine the optimal nozzles for effective control of insects, diseases, and weeds. Spray coverage and deposit density from seven types of nozzles at three different flow rates (0.76, 1.14, and 2.27 L min−1) and two target positions (0.50 and 0.70 m below the nozzle) were evaluated with water-sensitive papers (WSP) as targets under controlled environmental conditions. These nozzles included 80°and 110° conventional flat-fan nozzles, air induction flat-fan nozzles with the air intake hole either opened or sealed, hollow-cone nozzles, turbo jet nozzles, and twin-jet fan pattern nozzles. Spray coverage (percent area of a WSP covered with spray depositions) increased as flow rate increased for all nozzles. The hollow-cone nozzles had the highest coverage at both target positions while air induction nozzles had the lowest coverage.With the same flow rate, the 80° nozzles had higher spray coverage than 110° nozzles. Nozzles producing coarse spray had the lower spray coverage than nozzles producing fine and medium sprays. The 80° and 110° flat-fan nozzles at lower-than-specified operating pressures produced spray as coarse as that from the air induction nozzles with similar coverage. There was no significant difference in spray coverage between the same air induction nozzles whether the two air intake holes were opened or sealed. Spray coverage on targets at the 0.50 m position was greater than that at the 0.70 m position. Therefore, careful selection of nozzles could provide comparable performance for economical and effective spray coverage with optimal flow rates and operating pressures.

Effect of Droplet Size on Weed Control in Wheat

Effect of Droplet Size on Weed Control in WheatThe efficacy of different water volume and nozzle systems, comprising spinning-discs with two disc speeds (low volume, LV), a spinning-cage rotary atomizer (median volume, MV), a flat fan nozzle Teejet-11004 (high volume, HV), and no weed control, were assessed for the application of 2,4-D to control weeds in irrigated wheat. The herbicide was applied at the tillering stage of cultivated wheat, Ghods variety. Sprayer nozzle performance was evaluated in terms of wheat grain yield, weed shoot biomass, and wheat residual (straw), at the research farm of Shahrekord University in 2007 and 2008. ANOVA analysis indicated that nozzle type, and the year had significant effects on grain yield and dry biomass of weeds at 5% confidence. There was a significant difference between the two years of the experiment for all variants. The results indicated that the median diameter volume using the spinning disc (low disc speed) for herbicide application, gave better weed control than others. The spinning disc nozzle decreased water use and so it was cheaper to operate. It did not, however, significantly improve herbicide efficacy, especially in dense canopies compared with the conventional flat fan nozzles. The spinning-disc had more droplet uniformity at high disc speeds compared with the cage rotary atomizer, but was more effective for weed control at low disc speeds.

The Silsoe Spray Drift Model: A model of spray drift for the assessment of non-target exposures to pesticides

A computer model of spray drift was developed, from an earlier particle-tracking model ( Miller and Hadfield, 1989 ), which can be used to predict non-target exposures to pesticides. The extended model includes the effects of multiple nozzles on a boom and a forward speed so that it is better able to simulate application conditions appropriate to current field practice, particularly in the UK. The model was specifically developed for improving estimates of bystander dermal and inhaled spray drift exposure. It was validated against three experimental datasets of downwind airborne spray and ground deposit for FF110/1.2/3.0 conventional flat-fan nozzles spraying over either short grass or 0.65 m tall wheat crop. The model showed good agreement with measurements, but future work is required to validate the model against other nozzle designs.

Ground-based spectral reflectance measurements for evaluating the efficacy of aerially- applied glyphosate treatments

Aerial application of herbicides is a common tool in agricultural field management. The objective of this study was to evaluate the efficacy of glyphosate herbicide applied using aircraft fitted with both conventional and emerging aerial nozzle technologies. A weedy field was set up in a randomised complete block experimental design using three replicates. Four aerial spray technology treatments, electrostatic nozzles with charging off, electrostatic nozzles with charging on, conventional flat-fan hydraulic nozzles and rotary atomisers, were tested. To evaluate the glyphosate efficacy and performance of aerial spray technologies, spectral reflectance measurements were acquired using a ground-based sensing system for all treatment plots. Three measurements were taken at 1, 8, and 17 days after treatment (DAT). The statistical analyses indicated that glyphosate applied with different methods killed the weeds effectively compared to untreated areas at 17 DAT. Conventional flat-fan nozzles and rotary atomisers performed better than the electrostatic nozzles with charging off. There was no evidence to show that the electrostatic nozzle performed better with charging on or charging off. The results could provide applicators with guidance equipment configurations that can result in herbicide savings and optimised applications in other crops.

Development of a Canopy Opener to Improve Spray Deposition and Coverage Inside Soybean Canopies: Part 2: Opener Design with Field Experiments

Conventional boom sprayers usually are not effective in delivering droplets to inner parts of dense target canopies, such as soybeans at growth stages from R3 to R5. An experimental mechanical canopy opener was developed with the assistance of mathematical models and attached to a conventional boom sprayer to increase spray deposition and coverage inside soybean canopies. The opener consisted of a 2.5 cm diameter metal pipe to push canopies forward, and a frame for connecting the pipe to the spray boom. Field experiments were conducted to determine the amount of spray deposition and percentage of spray coverage on artificial targets at the middle and lower portions of soybean canopies with three opener depths (7.5, 15, and 22.5 cm), three opener widths (15, 25, and 35 cm), and two different sizes of flat-fan nozzles. Additional field experiments were conducted to compare spray deposition and coverage inside soybean canopies among treatments using an air-assisted sprayer, the conventional boom sprayer with the opener, and the boom sprayer with a conventional flat-fan nozzle and a dual-pattern nozzle assembly without the opener. At the time of experiments, the soybean plants were at R5 growth stage with an average height of 1.06 m. An opener width of 25 cm or larger significantly increased the spray deposition and coverage inside the canopies. An opener depth from 7.5 to 15 cm had better spray coverage than the 22.5 cm opener depth. The boom sprayer with the opener produced no significant difference in spray deposition and coverage at the middle of canopies compared to the air-assisted sprayer, but it did produce significantly lower spray deposition and coverage at the lower portions of canopies than the air-assisted sprayer. With assistance from the opener to push the top of canopies, spray deposition and coverage on targets inside soybean canopies by the boom sprayer was improved.

Spray Characteristics and Drift Reduction Potential with Air Induction and Conventional Flat-Fan Nozzles

Spray drift potential, spray coverage, droplet size, and spray pattern width for various sizes of air induction and conventional flat-fan nozzles with equivalent orifice areas were investigated and compared under laboratory conditions. Droplet sizes were measured with a laser imaging system; spray coverage on water-sensitive paper (WSP) was evaluated with a boom sprayer at a constant travel speed in a greenhouse, and ground and airborne spray deposits were determined in a wind tunnel at two wind velocities (2.5 and 5.0 m/s). Tests were also conducted to evaluate the effect of air-intake holes being sealed or open on spray characteristics of air induction nozzles. With the equivalent nominal flow rate, air induction nozzles had approximately 2.1 to 2.75 times larger exit orifice areas than the conventional nozzles. With the equivalent orifice area and equal liquid flow rate, there was no significant difference in droplet size, spray pattern width, spray coverage, ground spray deposit, and airborne deposit among regular air induction nozzles, air induction nozzles with two sealed air-intake holes, and conventional flat-fan nozzles. Spray characteristics of air induction nozzles could be achieved by conventional nozzles with the equivalent orifice size operated at the reduced operating pressure.

Nozzle-Adjuvant Formulation Interactions: Implications on Herbicide Efficacy

Abstract A series of adjuvants were developed to improve herbicide performance when applied through air induction nozzles. A series of research trials were conducted in 2004 and 2005 with clethodim, foramsulfuron, and glyphosate. Efficacy of these herbicides was reduced in over 30 % of all cases when applied through air induction nozzles compared to conventional flatfan nozzles. However, when modified forms of the adjuvants were used, efficacy increased approximately 25 % of cases with glyphosale, 40 % of cases with clethodim, and 90 % of cases with foramsulfuron when using air induction nozzles. A separate series of oil-based adjuvants developed had over 20 % air entrapment whereas conventional oil-based adjuvants had 5 % or less air entrapment when using air induction nozzles. Research conducted in the field in 2005 indicated that these novel formulations may improve herbicide efficacy.

Low-drift fungicide application technology for sclerotinia stem rot control in canola

Five methods of fungicide application were made to canola ( Brassica napus) to determine the effect of nozzle type and pressure on sclerotinia stem rot ( Sclerotinia sclerotiorum) infection of canola and crop yield. Benomyl and vinclozolin fungicides were effective in reducing stem rot in treated plots and increasing yield over the unsprayed check in 2 of 3 years. Variation in product performance among years indicated that environmental conditions had a major effect on crop development, sclerotinia stem rot infection, the effect of fungicides and subsequent yield. Overall, conventional flat fan nozzles (TeeJet XR), low-drift venturi nozzles (CFFC TurboDrop) and hollow cone nozzles (TeeJet TXVS-8) were all effective at reducing disease symptoms. Both 275 and 550 kPa provided similar performance although increasing the venturi nozzle pressure to 550 kPa improved disease control slightly. These results indicate that venturi nozzle technology is appropriate for use with foliar fungicides for sclerotinia control in canola provided pressures are adjusted to optimize nozzle performance.

Spray Penetration into Peanut Canopies with Hydraulic Nozzle Tips

The spray penetration into peanut canopies with single- and twin-row planting systems at three growth stages was investigated with four different types of hydraulic nozzle tips (flat fan, hollow cone, twin jet and air induction). The nozzles were operated at 276 kPa pressure, 6·4 km h −1 travel speed, and 0·5 m above the top of canopies. The canopy leaf area index (LAI) and height were measured for each test and correlated with spray deposits at the bottom and middle of peanut canopies. Spray deposits at the top, middle and bottom of canopies were determined with a spray mixture containing water and a fluorescent tracer. The concentration of spray samples were corrected with the calibration of the photo degradation of the tracer exposed to direct sunlight, under artificial shade and in a dark room. Plants with single- and twin-row planting systems received significantly different spray deposits within peanut canopies. For all four nozzles during the growth season, the spray deposits decreased dramatically from the top to the bottom of canopies, and also tended to linearly decrease as LAI increased. Compared to the flat fan nozzle at the bottom of canopies at 75 days after planting, the air induction nozzle produced 2·6 times higher spray deposits for single-row plants and 1·6 times higher spray deposits for twin-row plants. During the three growth stages, the air induction nozzle produced the highest mean spray deposit at the bottom of canopies, followed by the twin jet and then hollow cone nozzles. The conventional flat fan nozzle had the lowest spray penetration performance among the four types of nozzles.

Nozzle, Spray Volume, and Adjuvant Effects on Carfentrazone and Imazamox Efficacy1

Abstract: Field experiments were conducted to determine the influence of nozzle type, spray volume, and adjuvants on herbicide efficacy. Carfentrazone and imazamox, representing contact and translocated herbicides, respectively, were equally or more effective when applied with drift-reducing TurboDrop or Drift Guard nozzles than the conventional flat-fan nozzle in 95% of the comparisons. Imazamox was equally effective when applied in 47, 94, or 190 L/ha spray volume, regardless of nozzle type or adjuvant. Carfentrazone applied in 47 L/ha spray volume controlled flax and sunflower as well as in 94 or 190 L/ha, provided urea ammonium nitrate fertilizer and either nonionic surfactant or methylated vegetable oil were included in the spray mixture. Conversely, carfentrazone with only urea ammonium nitrate was less effective when applied in 47 than in 94 or 190 L/ha spray volume. Carfentrazone and imazamox applied in low spray volumes (47 L/ha) gave consistent control when an effective adjuvant was included in ...

Drift-Reducing Nozzle Effects on Herbicide Performance1

Abstract: Herbicide efficacy, coverage, and retention were evaluated for spray applied through Drift Guard, Turbo TeeJet, AI TeeJet, and TurboDrop drift-reducing nozzles compared to a conventional flat-fan nozzle. Percentage spray coverage detected on water-sensitive cards was greater for conventional and Drift Guard nozzles than for Turbo TeeJet, AI TeeJet, and TurboDrop nozzles. Spray without adjuvants was retained better by redroot pigweed for treatments applied with conventional and Drift Guard nozzles than Turbo TeeJet, AI TeeJet, and TurboDrop nozzles. However, spray with adjuvants was retained similarly for all nozzle types when averaged over spray adjuvant and two weed species. The efficiency of spray retention was greater for spray applied in 47 than in 190 L/ha spray volume for all nozzles. Paraquat and glyphosate, representing contact and translocated herbicides, respectively, provided similar grass species control for all nozzle types, regardless of spray volume. Paraquat and glyphosate were a...

Effects of formulation on spray nozzle performance for applications from ground-based boom sprayers

The performance of agricultural spray nozzles has components relating to the droplet size and velocity distributions within the spray, spray structure, entrained air characteristics and the spray volume distribution pattern. The interaction of these physical performance parameters has been shown to influence target retention, efficacy and the risk of drift. Results from a number of studies have also shown that the physical properties of the spray liquid have a substantial effect on spray formation such that changes in formulation type can give changes in spray characteristics that would be equivalent to doubling the flow rate through conventional hydraulic flat fan nozzles. The interactions between the physical properties of the spray liquid and the characteristics of the spray formed is a function of nozzle design. However, analysis of a large data set for a range of types of hydraulic pressure nozzle has shown that sprays formed from liquids based on emulsions generally have a coarser droplet size distribution compared with sprays formed from surfactant solutions. Although some correlation between dynamic surface tension and viscosity with spray droplet size has been established, the results from work reviewed in this paper suggest that other factors also influence the spray formation process. Air induction and twin-fluid nozzles mix air and liquid in the spray formulation process to produce droplets with air inclusions. These nozzle designs have been found to have a performance that is more sensitive to changes in spray liquid properties compared with hydraulic pressure nozzles and to exhibit trends that are different from those of conventional nozzle types.

A comparison of the drift potential of a novel twin fluid nozzle with conventional low volume flat fan nozzles when using a range of adjuvants

Spray drift from a novel twin fluid nozzle and low volume hydraulic pressure flat-fan nozzles has been measured in a wind tunnel. At a wind speed of 4.2 m s −1, drift from the twin fluid nozzle, spraying a range of adjuvants increased with decreasing flow rate. Emulsifiable oil adjuvants produced less drift than an ethoxylated alcohol surfactant, in general agreement with data on in-flight droplet spectra. Comparing drift between the twin fluid nozzle and the flat fan nozzles at a constant flow rate of 600 ml min −1 showed that drift from the former was intermediate between standard and low-drift nozzles. Drift increased with increasing spray release height, but for the twin fluid nozzle at 400 ml min −1 at 50 cm was smaller than that from the same nozzle atomising 150 ml min −1 at a height of 35 cm. Air inclusions in droplets from the twin fluid nozzles did not influence drift. The need for a technique to measure the mass of droplets containing air inclusions is highlighted and the method of plotting drift at variable wind speeds is discussed.

Deposition and efficiency of herbicide sprays in sugar beet with twin-fluid, low-drift and conventional hydraulic nozzles

Four low-drift nozzles working at various pressures, one twin-fluid nozzle at two liquid and air pressures and two conventional flat-fan nozzles were compared with respect to spray deposition and herbicidal efficacy. Measurements of spray deposit on oats ( Avena sativa) and white mustard ( Sinapis alba) using a tracer showed that conventional nozzles were superior to the other nozzle types in most settings. Low-drift nozzles in the majority of settings and the twin-fluid nozzle at low pressures gave poor deposition on oats. Deposition on white mustard was greater than on oats and differences between spray methods small, although highly variable with the twin-fluid nozzle. Herbicide applications in sugar beet fields did not reveal any difference in weed control or crop vigour between the spray methods, but weed counts were affected by the dose level applied. The design of spray application experiments is discussed.

383. Vacuum and gas photocells: J. Sharpe, Industr. Electron., 1 (2), Nov. 1962, 70–74

Five methods of fungicide application were made to canola (Brassica napus) to determine the effect of nozzle type and pressure on sclerotinia stem rot (Sclerotinia sclerotiorum) infection of canola and crop yield. Benomyl and vinclozolin fungicides were effective in reducing stem rot in treated plots and increasing yield over the unsprayed check in 2 of 3 years. Variation in product performance among years indicated that environmental conditions had a major effect on crop development, sclerotinia stem rot infection, the effect of fungicides and subsequent yield. Overall, conventional flat fan nozzles (TeeJet XR), low-drift venturi nozzles (CFFC TurboDrop) and hollow cone nozzles (TeeJet TXVS-8) were all effective at reducing disease symptoms. Both 275 and 550 kPa provided similar performance although increasing the venturi nozzle pressure to 550 kPa improved disease control slightly. These results indicate that venturi nozzle technology is appropriate for use with foliar fungicides for sclerotinia control in canola provided pressures are adjusted to optimize nozzle performance.

376. Cold cathode discharge tubes: J. F. Dix and K. B. Reed, Electron. Techn., 39, Jan. 1962, 31–37

Five methods of fungicide application were made to canola (Brassica napus) to determine the effect of nozzle type and pressure on sclerotinia stem rot (Sclerotinia sclerotiorum) infection of canola and crop yield. Benomyl and vinclozolin fungicides were effective in reducing stem rot in treated plots and increasing yield over the unsprayed check in 2 of 3 years. Variation in product performance among years indicated that environmental conditions had a major effect on crop development, sclerotinia stem rot infection, the effect of fungicides and subsequent yield. Overall, conventional flat fan nozzles (TeeJet XR), low-drift venturi nozzles (CFFC TurboDrop) and hollow cone nozzles (TeeJet TXVS-8) were all effective at reducing disease symptoms. Both 275 and 550 kPa provided similar performance although increasing the venturi nozzle pressure to 550 kPa improved disease control slightly. These results indicate that venturi nozzle technology is appropriate for use with foliar fungicides for sclerotinia control in canola provided pressures are adjusted to optimize nozzle performance.