IllIlluunjgllljulllmwwill L , 'HFSIS This is to certify that the thesis entitled AN ANALYSIS OF SOME SPRAY FACTORS IN CONTROLLED POROSITY LOW VOLUME AND CONVENTIONAL GROUND ORCHARD SPRAY SYSTEMS presented by Henry William Hogmire, Jr. has been accepted towards fulfillment of the requirements for Ph .D 'Jegree in Entomology W3 (A, H 0W1?“k U Majorgrgfessor Date ’5 12ml ”7% 0-7639 OVERDUE FINES ARE 25C ”‘31 DAY PER II‘lCM Return to book drop to remove this checkout from your record. l- - . # yt‘V“ f, :“ 'I. {I \w y" > x , J - ~ 5. ,... L1,»? ’37 it: U‘ 4_ J ' o p, I AN ANALYSIS OF SOME SPRAY FACTORS IN CONTROLLED POROSITY LOW VOLUME AND CONVENTIONAL GROUND ORCHARD SPRAY SYSTEMS By Henry William Hogmire, Jr. A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Entomology 1979 ABSTRACT AN ANALYSIS OF SOME SPRAY FACTORS IN CONTROLLED POROSITY LOW VOLUME AND CONVENTIONAL GROUND ORCHARD SPRAY SYSTEMS By Henry William Hogmire, Jr. A controlled porosity low volume spray system generally trans- ported more pesticide to semi-dwarf apple trees than a conventional spray system, however, the low volume spray distribution was usually less uniform. The use of a water soluble dye to study spray trans- port revealed that the uniformity of low volume spray distribution could be improved by increasing air velocity and, to a lesser ex- tent, droplet size. The low volume spray system was generally as effective, if not superior to the conventional system in the level of pest control achieved. An analysis of the spray pattern from each of 2 Beecomist sleeves on the low volume spray system revealed that the position of the spinning sleeves should be altered when spraying different size trees in order to optimize spray distribution and maximize spray deposition. The mean tree deposit in standard size trees was 44 and 47% less than that delivered to semi-dwarf trees by the conventional and low volume spray systems, respectively. The differences in mean deposit between tree sizes is largely due to low deposits in the center region of standard size trees which had a denser foliage canopy and were wider in diameter than semi-dwarf trees. Henry William Hogmire, Jr. Beecomist spinning sleeve nozzles produced much narrower, smaller droplet spray spectra than those produced by conventional nozzle types. Conventional spray droplet distributions which passed through foliage contained a greater proportion of droplets in smaller size classes than distributions obtained in an open environment. The fact that this difference was practically non-existent‘with the low volume spray system supports the use of small droplet sprays for efficient pesticide transport into foliage habitats. The porosity and construction material has virtually no effect on the spray droplet spectra produced by porous Beecomist sleeves. The spray droplet spectrum produced by a perforated stainless steel sleeve is quite similar to that of the porous sleeve types. Spray droplet spectra are greatly influenced by the rotational velocity of spinning sleeves and spray formulation, and to a lesser extent by flow rate and air velocity. The efficiency of a droplet impingement harp for sampling spray spectra depends on the wire size used, the droplet size being delivered and velocity of droplet travel. ACKNOWLEDGEMENTS The author wishes to express sincere appreciation to Dr. Angus J. Howitt for his guidance and support throughout the course of this study. The author also thanks Drs. George S. Ayers, Chester M. Himel, George W. Bird and Edward J. Klos for their services on the guidance committee. The author is indebted to Dr. Richard Leavitt (Pesticide Research Center, Mich. State Univ.) for pesticide residue analyses; Dr. Henry J. Retzer and Mr. Lowell E. Campbell (USDA Beltsville, Maryland) for the use of an optical array spectro- meter probe and assistance in spray spectra studies; and to Miss Diana Haynes for spray droplet sizing. A very special thanks is extended to all the staff at the Trevor Nichols Experimental Farm during the past 3 years, with- out whose help this work would not have been possible. ii TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . . LIST OF FIGURES. . . . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . . METHODS AND MATERIALS. . . . . . . . . . . RESULTS AND DISCUSSION . . . . . . . . . . Insecticide Mass Transport Study. . . Miticide and Mite Distribution Study. The Effect of Air Velocity, Sleeve Spin Analysis of Spray Distribution Delivered From Each (2) Speed and of Liquid Proportioning to 2 Beecomist Sleeves on Spray Distribution Delivered by a Low Volume Spray System Ratio The Beecomist Sleeve on a Low Volume Spray System . . . . . . Comparison of Dye Distribution Delivered by Low Volume and Conventional Spray Systems to Semi-Dwarf and Standard Size Red Delicious Apple Trees. . . . . . . . . . . . . . Spray Droplet Spectra Analysis of a Conventional and Low Volume Spray System as Determined in Open and Foliage Environments With a Droplet Impingement Harp. . . . . . . Studies on The Parameters Which Affect Spray Spectra Characteristics From Rotary Sleeve Nozzles. . . . . . . . A. The Effect of Sleeve Construction, Rotational Velo- city and Sprayer Air Velocity on Droplet Spectra . . B. The Effect of Flow Rate on Droplet Spectra . . . . . C. The Effect of Two Sprayheads on Droplet Spectra. . . D. The Effect of Formulation on Droplet Spectra . . . . E. The Droplet Spectrum of a Non-Aqueous Spray Medium as Determined With Both an Optic Probe and Droplet Impingement Harp . . . . . . . . . . . . . . . . . . REFERENCES CITED 0 O O C C O O O O O O O 0 iii Page .104 Table 10. LIST OF TABLES Guthion ZS residue (ug/cmz) and insect injury encountered as a function of low volume and conventional spray treat- ments to semi-dwarf Jonathan apple trees during 1976. . . . Acaraben 4E residue (ug/cmz) distribution as a function of low volume and conventional spray treatments to semi- dwarf Red Delicious apple trees on June 23, 1977. . . . . . Percent decrease from initial acaraben 4E deposit deliv- ered by low volume and conventional spray systems to semi- dwarf Red Delicious apple trees on June 23, 1977. . . . . . Distribution of European red mites, Panonychus ulmi (Koch), in semi-dwarf Red Delicious apple trees as effected by low volume and conventional spray applications of acaraben 4E on June 23, 1977. . . . . . . . . . . . . . . . . . . . . . Percent reduction (from pre-treatment count) of European red mite population in semi-dwarf Red Delicious apple trees as effected by low volume and conventional spray applica- tions of acaraben 4E on June 23, 1977 . . . . . . . . . . . The distribution of dye, delivered by a low volume spray system, in semi-dwarf Red Delicious apple trees as effected by air velocity, sleeve spin speed and ratio of liquid proportioning to 2 sleeves. . . . . . . . . . . . . . . . . Simulated dye distribution as effected by 2-sided spraying using data from low volume spray applications to l-side of semi-dwarf Red Delicious apple trees (table 6) . . . . . The distribution of dye delivered by low volume and conven- tional spray systems to semi-dwarf Red Delicious apple treesonAugust10,1978.................. The distribution of dye delivered by low volume and conven- tional spray systems to standard size Red Delicious apple trees on August 15, 1978. . . . . . . . . . . . . . . . . . Simulated dye distribution as effected by 2-sided spraying using data from low volume and conventional spray applica- tions to 1 side of semi-dwarf (table 8) and standard size (table 9) Red Delicious apple trees . . . . . . . . . . . . iv Page 38 4O 44 45 49 51 59 67 7O 74 Table 11. 12. 13. 14. 15. 16. 17. 18. 19. LIST OF TABLES (Continued) Page Spray droplet statistics for a conventional spray system as determined in open and foliage environ- ments with a droplet impingement harp. . . . . . . . . . . . 76 Spray droplet statistics for a controlled porosity low volume spray system as determined in open and foliage environments with a droplet impingement harp . . . . 77 The effect of sleeve construction, rotational velocity and carrier air velocity on the aqueous droplet spec- trum delivered by Beecomist sleeves. . . . . . . . . . . . . 80 The effect of delivery rate on the aqueous spray drop- let spectrum produced by 70 um polyethylene and perfor- ated stainless steel Beecomist sleeves . . . . . . . . . . . 93 The effect of delivery rate, and sampling height and distance on the aqueous spray droplet spectrum pro- duced by two Beecomist perforated stainless steel sleeves. . 95 The effect of various chemical formulations on the spray droplet spectrum delivered by 70 um polyethylene and perforated stainless steel Beecomist sleeves . . . . . . . . 97 The effect of carrier air velocity and sleeve rotational velocity on the spray droplet spectrum of a water soluble dye formulation delivered by a Beecomist perforated stainless steel sleeve . . . . . . . . . . . . . . . . . . .100 The spray droplet spectrum of technical halathion deliv- ered by several Beecomist sleeve types . . . . . . . . . . .101 The spray droplet spectrum of dioctyl phthalate delivered by 70 um polyethylene and perforated stainless steel Beeco- mist sleeves as determined with an optic probe and a drop- let impingement harp . . . . . . . . . . . . . . . . . . . .102 7&8. 9810. 11. 12. 13. LIST OF FIGURES Sampling regions in semi—dwarf Red Delicious apple trees Absorbance spectrum of water soluble dyes at a concen- tration of 4 ug/ml + 0.8 ug/ml of orthene 758 in buffered ascorbic acid solution. . . . . . . . . . . . Absorbance of water soluble dyes as a function of con- centration (+ orthene 755 at 1/5 of dye concentration) in buffered ascorbic acid solution . . . . . . . . . . Sampling regions in standard size Red Delicious apple trees. I O C O O O O O O O O O I O O O O O O O O O O 0 Mean tree residue (ug/cmz) of acaraben 4E as a function of time after spraying semi-dwarf Red Delicious apple trees with low volume and conventional spray systems . . Mean tree population of European red mites in semi-dwarf Red Delicious apple trees as a function of time after spraying acaraben 4E with low volume and conventional Spray systems. 0 ' O O O O O O O I O O O O O O O O O O O The effect of air velocity and sleeve spin speed on the distribution of dye, delivered (equal sleeve delivery) by a low volume spray system, in semi-dwarf Red Delicious apple trees I O O O O O O O O O O O O O O O O I I O O O The effect of air velocity and sleeve spin speed on the distribution of dye, delivered (unequal sleeve delivery) by a low volume spray system, in semi-dwarf Red Delicious apple trees. I O O O O O O O O O O O O O O O I I O O O O O The distribution of dye in a semi-dwarf Red Delicious apple tree as delivered by each (2) Beecomist sleeve on a low volume spray system . . . . . . . . . . . . . The distribution of dye in a wooden spray stand as del- ivered by each (2) Beecomist sleeve on a low volume spray system I C O O O O O O O O I O O O O O C C O C O The distribution of dye in a semi-dwarf Red Delicious apple tree as delivered by low volume (A) and conven- tional (B) spray systems . . . . . . . . . . . . . . . . . V1 Page 17 19 21 28 43 48 53 56 62 65 69 Figure 14. 15. 16. 17. 18. 19. LIST OF FIGURES (Continued) Page The distribution of dye in a standard size Red Delicious apple tree as delivered by low volume (A) and conventional (B) spray systems . . . . . . . . . . . . . 72 The effect of sleeve construction, rotational velo- city and carrier air velocity on the aqueous spray droplet spectrum delivered by Beecomist sleeves. . . . . . . 82 The effect of sprayer air velocity and sleeve rot- ational velocity on the aqueous spray droplet spec- trum delivered by 2 Beecomist sleeve types . . . . . . . . . 84 The effect of sprayer air velocity on volume median diameter (VMD) at 3 rotational velocities for 4 Beecomist sleeve types . . . . . . . . . . . . . . . . . . . 87 The effect of sleeve rotational velocity and sprayer air velocity on the percent number aqueous spray droplet spectrum delivered by a Beecomist 20 um porous stainless steel sleeve. . . . . . . . . . . . . . . . 90 Aqueous spray droplet spectra delivered by various n0221e types 0 O O O O O O O O O O O O O O O O O O O O O O O 92 1v-I4' INTRODUCTION The production of marketable fruit is heavily dependent upon the airborne transport of pesticides for suppressing pest popula- tions. The needless application of pesticides ("insurance" sprays) plus the fact that only a small proportion of the applied dose reaches the target makes pesticide use both an economically and ecologically inefficient tool for pest management (Von Rumker gt 3}. 1975, Steiner 1969). Despite the fact that spray application accounts for a sizeable percentage of fruit production costs (412 for apples in 1962) past concern was focused on the pest sup- pression effectiveness of a pesticide rather than on the efficiency of the application process (Brann 1964). As a result of the con- tinually increasing costs of pesticides and energy required for their application, as well as stricter regulations imposed by gov- ernmental agencies, increased emphasis has been placed on the efficiency of pesticide application. Research has resulted in a reduction of pesticide usage through better timing of spray applications (Brann 1964), and the develop- ment of integrated pest management (1PM) programs (Croft 1975, USDA 1974). A more efficient use of pesticides, however, through im- provements in spray application methodology has been rather limited. Throughout the developmental history of air assisted spraying (outlined by Fleming 1962) the only major improvement has been the gradual conversion from dilute to concentrate spray application. This reduction in spray volume has reduced the expenditure of time and labor in spraying operations, and conserved precious pesticide by minimizing loss due to run-off (Brann and Gunkel 1951, Williams and McMechan 1961, Brann 35 21. 1967). Although the development of concentrate spraying improved the efficiency of pesticide appli- cation, other facets of spray methodology including equipment de- sign remained virtually unchanged. Improvements in spray application methodology rely on a thorough understanding of the factors inherent in application equip- ment responsible for pesticide transport to the target. The effi- ciency with which a lethal pesticide dosage is delivered to the target organism is primarily dependent upon the sprayer's air stream and the size of the transport agent, the spray droplet, as well as interrelationships between these 2 factors (Fleming 1962). The air velocity and volume requirements for efficient pesticide trans- port and deposition depend upon the spray system, the size of drop- let being transported, the nature of the spray target, and the en- vironmental conditions encountered during spraying. A pneumatic nozzle requires a higher air velocity than a hydraulic type because the liquid is atomized by the air stream rather than by pressure (French 1942). It is believed that the pesticide transport efficiency for a given spray system depends upon a proper balance between the volume and velocity of air de- livered (Ingerson and Irons 1952, Potts gtngl. 1950, Garman 1953). Fleming (1962) concluded that the amount of spray transported over a given distance is proportional to the horsepower of the air stream, and that the proper ratio of air volume to velocity is dependent upon droplet size. For a given air energy, the larger the droplet the greater the initial air velocity which will be required to keep it airborne for a given distance. In studying the distribu- tion of sprays in apple trees as delivered by 3 sprayers (with different air velocities and volumes but equivalent energy} Randall (1971) discovered that the uniformity of distribution throughout the trees increased with increasing air volume. Hall gtugl. (1975) discovered that sprayers delivering lower volumes of air tend to lose their air velocity more rapidly as the distance from the out- let is increased. This reduction in air velocity also influences the uniformity of spray distribution since a certain minimum air velocity is needed to deflect canopy foliage to allow for droplet penetration and impingement. In a survey of grower practices in Ontario apple orchards, Fisher 35 31. (1976) discovered that the air stream's effect on spray coverage density and uniformity depend- ed upon tree height, spacing, foliage density, and wind conditions. Out of the concern for increased insecticide efficiency has arisen the concept of the biological optimum spray droplet size. According to Himel (1969a), "optimum-size droplets are those sizes small enough to be produced in maximum numbers for maximum coverage and large enough to have an optimum critical impingement velocity for optimum impingement on the target insect." In the use of space aerosols, Mount (1970) found that only droplets from 5-25 um dia- meter impinged efficiently on adult mosquitoes. Hadaway and Barlow (1965) discovered that only 10-30 um droplets penetrated foliar vegetation and impinged on the wings of tsetse flies. Himel and Moore (1967, 1969) indicated that insecticide spray droplets less than 50 um in diameter impinged with greatest efficiency on target insects in forest and cotton ecosystems. More recently, Spillman (1976) has shown that the catch probability for most flying insects reaches a maximum for droplets of 10-30 um in diameter. Statements up to this point concerning optimum droplet size have pertained to the impingement of droplets on insects at the time of application. Chemical control is also achieved secondarily through pest contact with pesticide residues. The atomization of a given volume of liquid as a fine spray provides for a greater droplet density on a treated surface as compared to an equivalent volume of liquid delivered as a coarse spray. The greater droplet density provided by small droplets increases the frequency of pest contact with pesticide residues resulting in higher mortality levels and/or shorter exposure times to achieve mortality as compared to an equivalent pesticide rate delivered as large droplets (Fisher 25 '21. 1974, Fisher and Menzies 1973, 1976). If droplets are too small however, as a result of atomization and/or evaporation, they may not have sufficient momentum to impinge on plant surfaces (Yeomans and Rogers 1953, Potts 1946, Cunningham st 21, 1962). Although an abundance of experimental evidence supports the efficiency of small droplet sprays (less than 50 um) for pest con- trol, the literature also contains data supporting the use of coarse sprays. Yeomans (1952) and Davis g£_§1, (1956) reported that sprays having an.MMD (mass median diameter) of 200-300 um provided the best control of forest defoliators. Wilson 25 31. (1963) indicated that there was little difference in the effect on pest control when spray was delivered as droplets ranging from 100 to 400 um in diameter. The existing controversy concerning an optimum spray droplet size for pesticide delivery systems is largely due to a lack of standardization in methodology for spray spectra analysis. The accuracy achieved in analyzing a spray droplet spectrum is depend- ent upon obtaining a droplet sample that is representative of the total spray spectrum produced. The droplet sample obtained is in- fluenced by the sampling device employed as well as the manner in which the sample is taken. Numerous techniques and devices are available for the collection and/or sizing of landed as well as airborne spray drOplets. A variety of flat impingement devices including kromekote cards (Rath- burn 1970), slides coated with magnesium oxide (May 1949) or teflon (Anderson and Schulte 1971), or containing a well filled with vis- cous polybutene (Fisher and Dougan 1970) have been used for the collection and sizing of spray droplets. These devices suffer from problems associated with variable spread factors and critical im- pingement velocity, and frequently do not provide a representative sample of the total spray spectrum. Slides and cards may provide a biased sample in favor of large droplets because smaller droplets cannot resist the deflected air flow around the sampling device as easily, and as a result do not impinge with the same degree of efficiency (Pieper 1972). Conventional spray cards can provide an unrealistic analysis of a spray spectrum in which a close correla- tion between spray deposit and insect mortality may be lacking (Buffam 5521. 1967). Yeomans $5 31. (1949) and Rathburn (1970) demonstrated that small diameter wires are a much more efficient collecting device for small diameter drOplets than glass slides, filter-paper, or leaf discs. In comparing the impingement efficiency of small dia- meter wire with magnesium oxide, and teflon coated slides, McDaniel (1976) discovered that a droplet impingement harp strung with 5 um diameter tungsten wire was the only collection device that provided a representative sample of the total spectrum of small droplet sprays. Although the sampling devices outlined above perform a useful function in particular spray situations they are artificial tar— gets which do not necessarily mimic the droplet catch capabilities of natural surfaces. Himel (1969b) reported on the use of a fluor- escent particle (FP) spray droplet tracer method whereby the size of spray droplets impinging on insects and their natural foliage environments could be determined. More recently, photography with scanning electron microscopy has also provided a means for sizing spray droplets impinged on pest organisms (Lofgren g£_§l, 1973, Owens and Bennett 1978). In addition to spray spectrum analysis by the measurement of landed droplets, various photographic techniques for the study of suspended aerosols have been reported (Cadle and Wiggins 1953, Rathburn and Miserocchi 1967). The appli- cation of laser technology to spray spectrum analysis provides the methodology for the measurement of spray droplets while in flight (Knollenberg 1970, Reichard gtngl. 1977, 1978) and after impingement on target organisms (Zinky 1969, Roberts gtngl. 1971). While the importance of small droplet sprays for pest control has clearly been demonstrated by fluorescent particle tracer stud- ies, scanning electron microscopy, and laser holography, it would appear that the significance of experimental data has not been realized by manufacturers of air blast spray equipment. Most agri- cultural spray nozzles deliver a wide range of droplet sizes, how- ever, droplets smaller than 50 um in diameter typically constitute less than 1-2% of the total spray volume delivered (Brown 1951, Bode 25 31. 1968, Reichard st 31. 1977, 1978). According to Himel (1969a) spray droplets larger than 100 um in diameter are primarily deposited on the ground, ground forage, and peripheral foliage within the ecosystem. These data indicate that conventional agri- cultural spray equipment is a highly inefficient means of deliver- ing pesticides to the target organism, frequently resulting in unnecessary environmental contamination. The production of narrow-spectrum, small droplet spray was realized with the development of an ultra low volume ground sprayer for fruit pest control (Howitt and Pshea 1965). Employing a Mini- Spin rotary nozzle delivering spray droplets estimated at 70-80 um in diameter resulted in excellent fruit pest control with less than 6.3 liters of spray volume per hectare. The narrowbspectrum, small droplet spray was produced by utilizing a sprayer air velo- city of 54 m/s for rotating the Mini-Spin nozzles at 150 r/s. It was discovered that variation in the rotational speed of the Mini- Spin caused by changes in sprayer air velocity effected the size of spray droplets produced. By employing a variable speed electric motor to power a rotary orifice cage it was possible to accurately control droplet size in a range varying from coarse to aerosol sized spray droplets (Howitt 25 31. 1966). In 1969 (Howitt 35 El! unpublished) the concept of controlled porosity low volume spray- ing was introduced by the replacement of orifice cages with porous Beecomist (Beeco Products Company) rotary sleeve nozzles. This spray system combines the advantages of reduced spray volumes (described above) and narrow-spectrum, small droplet sprays which is currently lacking in conventional air blast spray equipment. Due to the present inefficiency of spray application, this research was conducted to study the spray mass transport properties and spray spectra characteristics of a controlled porosity low volume and conventional air blast spray system with the hope of providing methodology for the improvement of spray application efficiency. METHODS AND MATERIALS Insecticide Mass Transport Study. Two John Bean air blast sprayers, a model TM 1229 modified for low volume application and a C-336 CP conventional model were used to study insecticide transport to Jonathan apple trees during 1976. Guthion 28 was applied on a seasonal schedule (8 applications) beginning at petal fall at rates of 0.88, 1.75 and 3.51 1/ha with both spray systems. Benlate 50 WP was also applied in combination with the insecticide, at a rate of 1.7 kg/ha, for disease control. The low volume spray system was equipped with a Barnant model 7017 Masterflex peristaltic pump driven by a Graham model BD4R4 variable speed transmission. Liquid was pumped through tygon tubing to each of 4 (2 per side) electrically powered Beecomist perforated stain- less steel sleeves (Beeco Products Company) operated between 150 and 183 revolutions/second (r/s). The low volume spray system (PTO driven) was mounted by a 3-point hitch to a model 544 International tractor, and delivered 9.4 l of spray/ha at an average air velocity of 35.8 m/s. The engine driven conventional spray system was pulled by a model 504 International tractor, and delivered a spray volume of 1402.3 1/ha at an average air velocity of 40.2 m/s. Both spray- ers, traveling at 1.34 m/s, applied spray to both sides of semi- dwarf Jonathan apple trees averaging 3.4 m high and 4.0 m in dia- meter. A sample, consisting of twenty-five (2.54 cm diameter) leaf discs (5 from each of the 4 peripheral quadrants (1.5 m above 10 ground) + the top center (3.0 m above ground)), was taken from each of 3 replications/treatment. Samples were taken the day be- fore and 2 hrs after a given application to quantify the actual; deposit delivered on 4 separate dates of application. Samples were stored in a cooler with coolant and transferred, within 2-4 hrs after sampling, to a freezer (-25°C) until residue analyses were made. For residue analyses leaf discs were transferred from sample vial to a 500 ml flask to which several hexane washings of the sample vial were added. Sixty m1 of 25% acetone in hexane extract- ant were added to the flask which was stoppered and shaken for 10 minutes on a Burrell wrist-action shaker. The liquid was poured into a 250 ml separatory funnel and the process was repeated with 2 more 10 min extractions of equivalent volume. Acetone was removed with three 15 m1 washings of 1% NaCl in distilled water. The hexane layer was dried with anhydrous sodium sulfate and concentrated to 10 m1 under vacuum on a rota-evaporator at 55°C. Analyses were made with a Tracor 560 gas chromatograph equipped with a flame photometric detector set at optimum sensitivity for phosphorus. The chromatographic column was glass, 1.83 m x 4 mm i.d., packed with 3% SE—30 on 60/80 mesh Gas Chrom Q. Carrier gas was helium at 50 cc/min. Operating temperatures were: column, 220°C; inlet, 240°C; detector, 320°C. Under these conditions, the retention time was 5 minutes. Quantitation was by peak area. The mean (duplicate determinations) recovery of guthion from spiked 11 apple leaves was 90% at the 0.50 ug/cm2 level, and 95% at the 5.0 ug/cm2 level. The detection limit was 0.01 ug/cmz. One hundred apples (20 from each of the 5 sampling regions) from each of the 3 replications/treatment were picked and evaluated for insect injury 2 weeks after the last application. Miticide and Mite Distribution Study. Both John Bean sprayers described above were employed in this study, and operated under the previously described air stream con- ditions. The electric motor power source for the Beecomist sleeves on the low volume spray system was replaced with a model 361 hydraul- ic gear motor (Beeco Products Company) since it was discovered that high liquid flow rates and/or viscous pesticide formulations may reduce the spinning speed of electrically driven sleeves. The use of a hydraulic power source reduced the variation encountered in .sleeve spin speed and consequently droplet size produced under var- ious flow conditions. Beecomist 60 um porous polyethylene sleeves were substituted for the perforated stainless steel type (used above because of wettable powder fungicide formulation which would not pass through porous sleeves). Acaraben 4E was applied by both spray systems at a rate of 9.4 1/ha with the low volume and conventional spray systems cali- brated to deliver a total spray volume of 18.7 and 1869.8 l/ha res- pectively. The miticide was delivered (June 22, 1977) at a sprayer travel speed of 1.34 m/s to both sides of semi-dwarf Red Delicious apple trees averaging 4.1 m high and 4.6 m in diameter. Each of 12 5 replications/treatment was sampled in 4 tree regions consisting of the periphery, middle (halfway between periphery and center) and center at 1.8 m above ground, and top center at 3.7 m above ground. A sample consisting of twenty (2.54 cm diameter) leaf discs (5 from each of the 4 tree quadrants) was taken from each sampling region at 2 hrs, and 3,7,14 and 21 days after application. Samples were stored in a cooler with coolant and transferred, with- in 2-4 hrs after sampling, to a freezer (-25°C) until residue analyses were made. For residue analyses, the same extraction procedure as out- lined in the previous study was followed. The 10 m1 hexane extract was transferred to a micro-column packed with 2.0 g of deactivated 60/100 mesh Florisil used for sample clean-up. Acaraben 4E (chloro- benzilate) was eluted with 70 m1 of 47% hexane/3% acetonitrile/50% methylene chloride eluant. The eluted liquid was concentrated un- der vacuum to 10 m1 using a roto-evaporator at 55°C. Analyses were made with a Beckman GC 72-5 gas chromatograph equipped with a non-radioactive Beckman electron-capture detector set at Optimum sensitivity. The chromatographic column was glass, 1.83 m x 4 mm i.d., packed with 5% SE-30 on 60/80 mesh Gas Chrom Q. Carrier gas was helium at 50 cc/min. Operating temperatures were: column, 210°C; inlet, 250°C; detector, 320°C. Under these condi- tions, the retention time was 3.8 min. The identity of chloroben— zilate was confirmed using an identical sized column packed with 1.5% OV-17/1.95% QF-l on 80/100 mesh Gas Chrom Q, and operated at 13 a temperature of 200°C and helium flow rate of 60 cc/min. Reten- tion time under these conditions was 4.6 min. Sample quantitation was by peak area. The mean (duplicate determinations) recovery of chlorobenzilate from spiked apple leaves was 95% at the 0.63 ug/cm2 level, and 99% at the 6.3 ug/cm2 level. The detection limit was 0.01 ug/cmz. The population distribution of European red mite (Panonychus .232; Koch) active stages was determined, for miticide treated trees and a control, 1 day before, and at 3,7,14 and 21 days after spray application. Twenty leaves were sampled, as described above, from each of the 4 tree regions. Leaves were placed in covered pint containers (Lily-Tulip Cup Corp.) and stored in a cooler with cool- ant until transfer to a refrigerator for storage until mites could be counted. All samples were counted, within 48 hrs, by brushing leaves with a mite brushing machine (Leedom Engineering) onto a re- volving plate and making count determinations with a stereozoom microscope. The Effect 2; Air Velocity, Sleeve Spin Speed and Ratio g£_Liguid Proportioniggggg‘2'Beecomist Sleeves gn_The‘Spranyistribution Delivered by a Low Volume Spray System. Due to the discovered inferior air characteristics of the modified John Bean model TM 1229, a new experimental model low vol- ume spray system was developed. This trailer type model utilized a Bessler 8-bladed, 0.914 m fan powered by a 55 horsepower air- cooled, gasoline engine. The sprayer was pulled with a model 544 International tractor. 14 Because of the expense of pesticide residue analysis, which limited experimentation, and the delay in obtaining experimental results, it was felt necessary to investigate other methodology for studying spray distribution. Fluorescein (Matheson Coleman & Bell Manufacturing Chemists), a highly water soluble dye, was used in combination with Orthene 758 (Chevron Chemical Co.), a water soluble insecticide used to provide wettability, for studying spray distribution. The fluor- escein and orthene were applied at 3.7 and 0.74 kg/ha respectively in a total spray volume of 28 l/ha. Since apple trees were sprayed from only 1 side however, the amounts of solution and spray ingred- ients delivered were one half the above amounts. Fluid was delivered through tygon tubing to 2 Beecomist perforated stainless steel sleeves by a Barnant model 7017 Masterflex peristaltic pump powered by a 7 Hp gasoline engine, and driven through a Graham model BD4R4 variable speed transmission. The fluid was dispensed to each of 2 sleeves in equal proportions or with 2/3 of the spray volume be- ing delivered to the top sleeve by connecting the flow from 2 pump- ing units in the Masterflex pump to the top spray head with a y- connector. Both sleeves were hydraulically driven at a rotational velocity of 100 or 183 r/s as determined with a model 36 Pioneer photo-tech (Pioneer Electric and Research Corp.). The low volume spray system was operated at an air velocity of 22.4, 33.5 or 44.7 m/s. A model 3002 velometer (Salford Electrical Instruments LTD) was used to measure air velocity which was then related to fan 15 speed with the photo-tech. The desired air velocity was then achieved in the field by producing the required fan speed as determined with the photo-tech. Dye spray applications to semi-dwarf Red Delicious apple trees (averaging 4.1 m high and 4.6 m in diameter) were made during the early evening (after 7:00 p.m. E.D.T.) to minimize photo-degradation and unfavorable wind conditions. Treatments were replicated on 4 different evenings. The trees were sampled 15 minutes after spray application in each of 4 regions at 1.83 and 3.66 m above ground (Fig. 1). Ten leaves were picked from each region and placed in a covered pint container (Lily-Tulip Cup Corp.) which was transported to a station set up in the field for leaf punching. Ten leaf discs (2.54 cm diameter) were punched into 20 ml of 0.094 M anhydrous KZHPO4 (Mallinckrodt Inc.) and 0.047 M L-ascorbic acid (Sigma Chem- ical Co.) solution contained in 20 dram plastic screw cap vials (Owens-Illinois Prescription Containers). The K2HP04 was used to buffer the extracting solution at a pH of 7.2-7.4 preventing changes in solution color intensity as a result of changes in pH. The as- corbic acid was used to inhibit the oxidation of the cut leaf disc which contributed to background interference. Vials containing punched leaf discs were rotated on a conveyor for 15 minutes, and the Z transmittance of the sample was then determined using a Bausch & Lomb Spectronic-ZO calorimeter set at a wavelength of 485 um, (maximum absorbance, see Fig. 23). The dye deposit was quantitated using a standard curve (Fig. BB) prepared by series dilution of a 16 Figure 1. - Sampling regions in semi-dwarf Red Delicious apple trees. DIRECTION OF SPRAYER TRAVEL > SPRAY 17 1.2.29.4 ls >l ) NEAR CENTER 18 Figure 2. - Absorbance spectrum of water soluble dyes at a concen- tration of 4 ug/ml + 0.8 ug/ml of Orthene 758 in buf- fered ascorbic acid solution. A I Nigrosine (Eastman Kodak Company). B - Fluorescein (Matheson Coleman 8 Bell Manufacturing Chemists). C = Uranine (Sodium Fluorescein) (Fisher Scientific Company). 19 00w PE q 000 REE 505.963 own 000 why 09» mmv r o. . om L on .. oo . on . om 4 ON on - cm 00. aouougwsuml % 20 Figure 3. - Absorbance of water soluble dyes as a function of concentration (+ Orthene 758 at 1/5 of dye concen- tration) in buffered ascorbic acid solution. A = Uranine (Sodium Fluorescein) (Fisher Scientific Company). B = Fluorescein (Matheson Coleman & Bell Manufacturing Chemists). C = Nigrosine (Eastman Kodak Company). 21 ON 2633 co_B.=cmocoo 96 cm on O? on ON u q W 1 00 Nd v.0 qv ad 8 0.. N._ OOUDQJO t. 0.. 22 known concentration. The colorimeter was calibrated (100% trans- mittance) using a sample obtained from a solution containing 10 blank leaf discs processed in the same manner as treated discs. In order to determine percent dye recovery, 5 ul of the spray sol- ution was deposited onto an apple tree leaf (3 replications in field nearby) with a syringe at the time of spray application. This sample was harvested (leaf disc) at the end of experimentation, combined with 9 blank leaf discs and processed as outlined above. The calorimeter reading obtained was compared to that from a sample in which 5 ul of the same spray solution was injected into a vial containing 10 blank leaf discs in solution which were then processed in the same manner. A percent dye recovery of 95-97% was obtained. The methodology for determining the spray droplet spectra produced under the above operating conditions is reported under "studies on the parameters which affect spray spectra character- istics from rotary sleeve nozzles." Analysis 2£_Spray Distribution Delivered From Each (2) Beecomist Sleeve 22H§_Low Volume Spray System. Two water soluble dyes, uranine (sodium fluorescein) (Fisher Scientific Co.) and nigrosine (Eastman Kodak Co.), were used to study the distribution of spray in an apple tree delivered from each (2) Beecomist perforated stainless steel sleeve on the Bessler low volume spray system described previously. The sprayer was operated at a traveling speed of 1.34 m/s, with an air velocity of 40.2 m/s, and a sleeve spin speed on 183 r/s. Uranine + orthene 23 were applied (in combination) to 1 side of the trees at a rate (equivalent to 2-sided spraying) of 3.7 and 0.74 kg/ha respective- ly in a total spray volume of 56 l/ha delivered through the top (1.83 m above ground) sleeve. Each of 4 semi-dwarf Red Delicious apple trees (averaging 4.1 m high and 4.6 m in diameter) was sampled in the near, center and far regions (Fig. 1) of the tree at eleva- tions of 1.22, 1.83, 2.74 and 3.66 m above ground. The sampling and sample processing procedure outlined above was begun 15 minutes after spray application. The uranine deposit was quantitated at a wavelength of 485 nm (maximum absorbance, see Fig. 2C) using a standard curve (Fig. 3A) prepared by series dilution of a known. concentration. The percent recovery of uranine was 97%. Immediately after sampling all 4 uranine-treated replications, these same trees were sprayed at the same rate with nigrosine + orthene delivered in combination through the bottom (1.22 m above ground) sleeve. After sample processing, the nigrosine deposit was quantitated at a wavelength of 580 nm (maximum absorbance, see Fig. 2A) using a standard curve (Fig. 30) prepared by series dilu- tion of a known concentration. The percent recovery of nigrosine was 92%. Experimentation revealed that the presence of uranine (100% transmittance at 580 nm) did not interfere with the quantitation of nigrosine at 580 nm. The trees were not sprayed with uranine and nigrosine delivered simultaneously through their respective sleeves because the absorbance of nigrosine at 485 nm interfered 24 with uranine quantitation at this wavelength. The spray pattern from each (2) Beecomist perforated stain- less steel sleeve was also studied utilizing a wooden spray stand (5.49 m high and 4.58 m wide) placed in an apple orchard. Two 2.2 cm2 cover slips were fastened (with double-sided tape) to each of 3 (1x3") glass slides which were clipped with clothespins to the wooden stand at heights of 1.22, 1.83, 2.74, 3.66 and 5.49 m above ground at distances of 0.91, 3.20 and 5.49 m from the trav- eling sprayer. Nigrosine + orthene were applied in combination to 1 side of the stand at a rate (equivalent to 2-sided spraying) of 3.7 and 0.74 kg/ha respectively in a total spray volume of 56 l/ha. The sprayer was operated under the same conditions described in the previous experiment in this study. ‘The wooden stand was first sprayed with spray being delivered only through the bottom sleeve. Five minutes after spraying, the slides were removed and placed in slide boxes, and new slides were positioned. The procedure was repeated to provide a total of 3 replications. The experiment was then repeated with spray being delivered for 3 replications through the top sleeve. Cover slips were removed from the slides (in the lab) and deposited in 10 ml of buffered ascorbic acid solution. After brief agitation the nigrosine was quantitated as described above. Comparison g£_Dye Distribution Delivered by_Low Volume and Conven- tional_§prayySystens.£g_8emi-Dwarf and Standard Size Red Delicious Apple Trees. A Bessler experimental low volume (described above) and John 25 Bean model C-336 CP conventional sprayer were used to study dye mass transport to semi-dwarf (4.1 m high and 4.6 m in diameter) and standard size (6.1 m high and 7.3 m in diameter) Red Delicious apple trees. Both sprayers were operated at a travel speed of 1.34 m/s and average air velocity of 40.2 m/s. On August 10, 1978 at 2:40 p.m. E.D.T., semi-dwarf trees (4 replications) were sprayed with the conventional spray systau. Uranine + orthene were applied (in combination) to 1 side of the trees at a rate (equivalent to 2-sided spraying) of 3.7 and 0.74 kg/ha respectively in a total spray volume of 1869.8 l/ha. The top 2 nozzles of the sprayer were closed to avoid excessive spray loss over the tops of the trees. Samples were picked, processed and quantitated (as described previously) from 4 sampling regions (Fig. l) at heights of 1.83 and 3.66 m above ground, beginning 1/2 hr after spray application. After sampling completion, the same trees were sprayed with the Bessler low volume spray system delivering nigrosine + orthene (in combination) at an equivalent rate in a total spray volume (equivalent to 2-sided spraying) of 56 l/ha. Spray was delivered in equal proportions through 2 perforated stainless steel sleeves Operated at a spinning speed of 183 r/s. Samples were picked, pro- cessed and quantitated beginning 15 minutes after spray application. The percent recovery of uranine and nigrosine was 98 and 91% res- pectively. On August 15, 1978 at 3:00 p.m. E.D.T., standard size trees 26 (4 replications) were sprayed with the conventional spray system delivering uranine + orthene (in combination) at the same rate and volume per hectare as delivered to semi-dwarf trees. The spray system was operated as previously described, however, all nozzles (12) were employed. Samples were picked, processed and quanti- tated from 7 sampling regions (Fig. 4) at heights of 1.83, 3.66 and 5.49 m above ground. After sampling completion, the same trees were sprayed with the Bessler low volume spray system. Nigrosine + orthene were delivered (in combination) under the same conditions as described for semi-dwarf trees except that 2/3 of the spray volume was delivered through the top sleeve. Samples were picked, processed and quantitated to determine the nigrosine deposit. The percent recovery of uranine and nigrosine was 97 and 92% respectively. Spray Droplet Spectra Analysis p£_§_Conventional and Low Volume Spray System 2§_Determined‘$p_0pen and Foliage Environments With 2_Droplet Impipgement Hagp. Two John Bean sprayers, a modified model TM 1229 (described under "insecticide mass transport study") and a conventional model 477 CP were employed in this study. The conventional spray system was fitted with 10 No. 5 Whirl- mist nozzle caps (each delivering 90 ml/s at 7 kg/cmz) and operated at an average air velocity of 44.7 m/s. The low volume spray system was equipped with 2 hydraulically driven (183 r/s) Beecomist 60 um porous polyethylene sleeves (del- ivering 4.5 ml/s of liquid/sleeve) and operated at an average air 27 Figure 4. - Sampling regions in standard size Red Delicious apple trees a DIRECTION OF SPRAYER TRAVEL 29 velocity of 35.8 m/s. A droplet impingement harp (described by McDaniel 1976), strung with fine diameter wire, was used for collecting spray droplets of dioctyl phthalate (WOlverine Solvents Company). Di- octyl phthalate was used as a spray liquid in order to provide relatively non-volatile droplets for size determination. Strands of 5 um tungsten and 15 um stainless steel wire were used to collect droplets delivered from the low volume spray system, and these 2 sizes plus 25 um and 50 um stainless steel (Sigmund Cohn Corp.) were used for the conventional spray system. Harps were fastened with clothespins to a horizontal pole at a height of 1.83 and dis- tance of 3.05 m from the sprayers' air outlet. The average air velocity at this distance for the low volume and conventional spray systems was 5.4 and 11.6 m/s, respectively. Each sprayer was driven at 1.34 m/s and made 1 pass by their respective harps. Immediately after spraying, the harps (5 replications) were placed in covered boxes and transported to a photographic darkroom. The above procedure was repeated with harps positioned at the same height in the center of semi-dwarf Red Delicious apple trees (4.1 m high and 4.6 m in diameter) approximately 3.2 m from the sprayers' air outlet. The harps (5 replications) were sprayed as above, removed and placed in covered plastic boxes, and transported to the photographic darkroom. An Omega 10 x 13 cm photoenlarger was equipped with a Graflex Optar (Graflex, Inc.) 101 mm lens and a metal negative holder with 30 a 3.8 cm2 opening. The harp was positioned over the opening, and the enlarger was adjusted to project an image 25.4 cm long onto 20.3 x 25.4 cm Agfa BEH 1 No. 6 contrast photographic paper. The wire-droplet image was focused and then photographed (f. stop of f 22) onto the photographic paper thus providing a 6.67 fold en- largement. All harps were photographed within 6 hrs after sampling. Upon development of the photographic paper, the wire and spray drop- lets appeared white on a black background. The prints were cut into 0.64 cm wide strips and spliced end to end. The strips were threaded onto a photoreel viewing device (described by McDaniel 1976) and the droplets were sized by turning the threaded spool and moving the strips through the microscope field of view. The long and short axis of the droplet (impinged as an ellipse on the wire) was measured. The ocular micrometer measurements were fed into a com- puter program written to convert these data to spherical droplet size and volume statistics. A total of 200 droplets/replication for each wire size were measured for the low volume spray system. For the conventional spray system all the droplets on each wire size were measured. The total count ranged from 200-400 droplets/ replication, with the lower values characteristic of harps which had been placed in trees. Studies pp The Parameters Which Affect Spray Spectra Characteris- tics From Rotagy Sleeve Nozzles. General Methods, Materials and Experimental Conditions. The size of spray droplets delivered by the Bessler low volume 31 spray system under various operating conditions was determined with an optical array cloud droplet spectrometer probe [Particle Measuring System (PMS) model OAP-ZOOX]. Data from this probe was collected and stored in the particle data system (PMS model PDS- 100) which in turn was interfaced to a programmable desk calculator (Hewlett-Packard model 9815 A) that was programmed to print out droplet distribution statistics. The probe illuminates particles passing through the sampling area with laser light. Shadows of these particles are projected onto a linear array of photodiodes. An electrical signal propor- tional to the number of photodiodes shadowed is sent to the par- ticle data system. Built-in electronics reject out-of-focus, simultaneous, and partial drop images. In flight size measurements of droplet diameters can be made in the range of 18 to 563 um (22 size classes in 25 um increments) at particle velocities up to 125 m/s. When a sampling run is completed the size and number data is fed by manual switching into the calculator. This calcul- ator has been programmed to divide the counts in each size class by the sampling area for that class, and then compute droplet dis- tribution statistics. A sampling time of 2-4 minutes was used so that the total number of corrected counts was above 1000. Calibration of the systems was checked prior to experimentation by pouring glass beads of a known size range through the sampling area of the probe. A 1.3 cm thick sponge rubber boot covered by an absorbent cloth was fitted over the tips of the sampling tubes 32 to absorb the spray hitting the ends of the tubes and dribbling through the sampling area as random large drops. While this pro- cedure reduced random large drops it is not clear that all such drops were eliminated. Fluid was delivered to the Beecomist sprayheads by either an electronically controlled solid state peristaltic pump (Mano- stat Corp.) or by a gasoline engine (7 Hp) driven peristaltic pump (Barnant Corp. model 7017) driven through a Graham model BD4R4 variable speed transmission. Flow rates were adjusted to within $0.3 ml/s of the reported values. Reported air velocities repre- sent the average speed at the volute which was achieved by produc- ing the required fan speed as determined with the Pioneer photo- tach. Sleeve rotational velocities were measured with an electronic strobe (General Radio Co. model 1531) and represent *2 r/s of re- ported values. Exept where otherwise noted the experimental spray- er delivered spray (water) at the rate of 6.7 mlls through the bottom sleeve of 1 side. The sprayer was operated at an air vel- ocity (at the volute opening) of 33.5 m/s, and a sleeve rotational velocity of 183 r/s. The optic probe was positioned at a horizon- tal distance of 0.91 m and a vertical distance of 0.15 m from the functioning sprayhead. Surface tension of spray solutions was determined with a DuNouy tensionmeter (Central Scientific Co.) at 23-25°C. All points in spray spectra plots are based on droplet size means of the individual counting ranges (droplet size classes). 33 A. The Effect 2£_Sleeve Construction, Rotational Velocity and Sprayer Air Velocity pp Droplet Spectra. To test the effect of sleeve construction (both constructional material and differences in porosity) the following sleeves were used: 20 and 60 um porous stainless steel, 70 um porous polyethy- lene and perforated stainless steel. All combinations of air vel- ocities of 22.4 and 44.7 m/s and sleeve rotational velocities of 50, 100 and 183 r/s were studied. Data were compared with spray spectra delivered by a model 3P50 Kinkelder and a model 3000 CP FMC spray system. B. The Effect g£_Flow Rate pp_Drop1et Spectra. The effect of spray liquid delivery rate on draplet spectra was studied at rates of 1.7, 6.7, 13.3 and 26.7 m1/s with both the 70 um porous polyethylene and perforated stainless steel sleeves. C. The Effect 22 Two Sprayheads gp_Droplet Spectra. The possibility of in-flight coalescence affecting droplet spectra in zones of overlap from 2 or more sprayheads was studied with 2 sprayheads equipped with perforated stainless steel sleeves at flow rates of 6.7 and 17.8 m1/sleeve. The probe was positioned at horizontal distances of 0.91 and 3.05 m and vertical distances of 1.37, 2.13 and 3.05 m (0.15, 0.91 and 1.83 m above lower spray- head) above ground. D. The Effect g£_Formulation gp_qup1 thpectra. Diazinon 4EC (Ciba Geigy Corp.), Sevin 80W? (Union Carbide Corp.) 34 and Captan 4F (Stauffer Chemical Co.) were selected as represen- tative of emulsifiiable concentrate, wettable powder and flowable pesticide formulations, respectively. Pesticide concentrations used were: Diazinon, 42, 84 and 167 m1/1; Sevin,.200 g/l; Captan, 333 m1/1. The effects of Bivert (Stull Chemical Company) and Nalco-Trol (Nalco Chemical Company) were studied alone and in combination with each of the formulations. The concentrations of Bivert and Nalco-Trol in all cases were 83 and 0.8 m1/1, respec- tively. Formulation concentrations used in combination with Bivert or Nalco-Trol were: Diazinon, 167 ml/l; Sevin, 200 g/l; Captan, 333 ml/l. The effect of formulation on droplet spectra was stud— ied using 70 um porous polyethylene (for Bivert, Nalco-Trol and Diazinon formulations) and perforated stainless steel (all formul- ations) sleeves. The droplet spectrum of a dye formulation (uranine + orthene 75S) was also studied. Uranine + orthene were delivered (in com— bination) at a concentration of 132.1 and 26.4 g/l respectively, at a flow rate of 6.7 mlls. All combinations of sprayer air velo- cities of 22.4, 33.5 and 44.7 m/s, and sleeve rotational veloci- ties of 100 and 183 r/s were studied using the dye formulation. The effect of a non-aqueous formulation (technical Malathion) (American Cyanamid Company) on the droplet spectrum delivered by 20 um, 60 um and perforated stainless steel, and 70 um polyethylene sleeves was studied. The technical Malathion was delivered at a rate of 15.8 ml/s. 35 E. The Droplet Spectrum of a Non-Aqueous Sprgy Medium as Deter- ‘ mined With BOth an Optic —Probe and Droplet Impingement“ Ha_p. The spray droplet spectrum of dioctyl phthalate as delivered by 70 um polyethylene and perforated stainless steel sleeves (at 6.7 ml/s) was determined with an optic probe positioned at a height of 1.37 m (0.15 m above sprayhead) at distances of 0.91 and 3.05 m from the sprayer air outlet. Following a probe sampling time of 120 or 240 seconds (depending on distance), a droplet impingement harp (described above) was used to also determine the droplet spec- trum from each sleeve type at both distances. Harps (3 replications/ sleeve type/distance), strung with 5 um tungsten and 15 um stain- less steel wire, were attached to a lath with a clothespin and positioned l at a time in the sprayer's airstream (13.4 m/s at 0.91 m; 6.3 m/s at 3.05 m) for 1-2 sec at a height of 1.37 m. Immediately after obtaining a sample a harp was placed in a covered plastic box. At the end of all sampling, harps were packed in a cardboard box layered with cotton for transport from Beltsville, Maryland (location of experiment) to a photographic darkroom in Fennville, Michigan. All harps were photographed (as described above) within 48 hrs after sampling. Droplets were measured through a microscope employing the photoreel viewing device. A total of 400 droplets/replication, or the total number present (if less) were measured for each wire size. Smaller sample sizes (ZOO-300 droplets) were encountered at the greater sampling distance. A computer program was used to convert dr0p1et (ellipse) 36 measurements to spherical droplet size and volume statistics. Volume percentages for the total number of droplets of a given size were cumulated and converted to probit values. Droplet sizes and probit values were fed into a linear regression program to determine the predicted droplet size (this size and smaller) representing 10, 50 and 90% of the spray volume. 37 RESULTS AND DISCUSSION Insecticide Mass Transport Study. The quantitation of Guthion 28 transport to semi-dwarf Jon- athan apple trees by low volume and conventional spray systems is reported in table 1. This table also reports the insect injury to fruit encountered as a function of both spray systems as well as a control. Although the average (season) insecticide deposit delivered by the low volume spray system was higher (for all rates) than for the conventional system, the difference was not signifi- cant (P=0.05) except for the 1.75 l/ha rate. In a separate analy- sis, no significant difference in deposit between dates of appli- cation was found except for the low volume spray system at a rate of 1.75 l/ha and the conventional spray system at a rate of 3.51 l/ha, where in both cases 1 date with a low deposit was encountered. No significant difference between spray systems on the per- cent of insect injured fruit encountered was noted. In comparing the percent of insect injured fruit encountered at insecticide rates of 0.88 and 1.75 l/ha, no significant difference was noted in the conventional treatments, however, in the low volume treat- ments injury encountered at the low rate was significantly greater. At first this difference appears puzzling since the low volume system delivered more insecticide (although not significant) at the low rate than the conventional system. It is believed that the reason for this occurrence lies in the fact that the insecti- cide deposit represents an average deposit on leaves taken from 38 .auosuasum amouw was umHHoummmH mouuluwaum .uoaaouwmoa voucmnloovuano .uoaaoummma wovamnuumu mopaauoH n .Aam>mH mo.onmv uaoummwfiv hauamowmficwam won one umuuma aoaaou m hp vmaoaaom menace ao>ww m Ga mammz m a m.s o “.mfi s m.Ha . u n u u . Hopscoo m m.o m o.o m m.o a me. a me. 0 mm. u on. so as. Hm.m = a m.o m m.o as o.H a ma. on ma. pm HH. s 0H. n Hm. mn.H = m m.o as o.m on m.~ m mo. a mo.. s 50. m mo. a mo. mm.o Hmaoausm>cou m a.o m o.o pm o.H we on. a us. so am. me me. a mm. Hm.m = m 0.0 m m.o m m.o 0 am. so am. am OH. so am. on an. ma.H = a o.H p 0.0 u a.s pm as. as «H. as ma. n as. I mw.o maaHo> sou nmuoaaouwmma owaauuso, Suoz new: o~\m ¢~\n «\n «\o Amnxav unmaumoua anflm waaasoo commmm mm aoanuao "hp commamv uwsum «o N coaumuwaaad mo mama m.onma wafiuzv mmmuu madam amnumaOh Nunavuaaom ou unassumouu woken HMGOfiqu>coo was oaoao> 30H mo coauocom m an venousnouco human“ uoomna can Amau\w=v snowman mm coununo I .H manna 39 5 areas (4 bottom, 1 top) of the tree. The sample, representing the average tree deposit, could in fact have masked large differ- ences in deposit between the t0p and bottom regions of the tree. For example, inferior transport to the top of the tree by the low volume spray system could have resulted in the significant increase in injured fruit encountered at 0.88 1/ha, whereas the deposit achieved at twice this rate may have been sufficient to provide control. A low deposit in the top could have been offset by high deposit in the bottom thus yielding an average tree deposit great- er than that provided by the conventional spray system. Even though it appears that large differences in tree region deposit (which need to be investigated) occur with the low volume spray system, an acceptable level of pest control is possible at reduced insecticide rates with both spray systems. Miticide and Mite Distribution Study. The residue level of Acaraben 4E in 4 tree regions as a func- tion of spray system and time after application is presented in table 2. Miticide delivery by the low volume spray system resulted in a significant (P=0.05) difference in deposit between tree re- gions which was not observed in the conventional treatment. Even though the distribution was less uniform, the deposit delivered by the low volume spray system was significantly greater than that in the conventional treatment in 3 of the 4 tree regions. The reduced low volume deposit in the top of the tree supports the suspected occurrence in the previous experiment. It is believed 4O .AHo>mH no.0umv uamummmwu xausmuamwowam no: mum nouuma .vuaouw m>onm a oo.m u< u .vaaouw m>onm s mw.H u< a ooeaoo m 59 vm3oaaow seaflou cm>0m m :0 memo: m 0 00.0 0 00.0 00 00.0 0 00.0 0 00.0 0002 0000 = 0 00.0 0 00.0 0 00.0 00 00.0 00 00.0 0000000 = 0 00.0 0 00.0 0 00.0 00 00.0 0 00.0 0000000 0 0 00.0 0 00.0 0 00.0 0 00.0 0 00.0 0000000 : 0 00.0 0 00.0 0 00.0 0 00.0 0 00.0 0000000000 000000000000 0 00.0 0 00.0 0 00.0 0 00.0 0 00.0 000: 0000 = 0 00.0 0 00.0 0 00.0 0 00.0 0 00.0 0000000 z 0 00.0 0 00.0 0 00.0 00 00.0 0 00.0 0000000 = 0 00.0 0 00.0 00 00.0 0 00.0 0 00.0 0000002 = 0 00.0 0 00.0 0 00.0 0 00.0 0 00.0 0000000000 000000 300 00 .00 0 0 0 00000.0 00000 0000. monk coaumoaana< umum< 00mm n.00ma .mm mama so momma manna maowoaaon pom mumavlfiaom cu muaoaumouu amuam Henceuco>aoo can oaaHo> 30H mo nowuoaaw m we coaunnauumfim Amaoxwov mavfimmu we nonmemu< I .N manna 41 that miticide loss due to run-off (from high volumes of water) is part of the reason for the lower deposit in the conventional treat- ment. This was probably enhanced by the fact that the application was made in the early morning when the trees were laden with a heavy dew deposit. The residue level in the low volume treatment was significant- ly greater than the conventional treatment in all 3 regions in the bottom of the tree, as well as the tree average, through 21 days after application. The average tree residue through 21 days after application is graphically presented in figure 5. A comparison of both spray systems with respect to the percent decrease in residue from the initial deposit (table 3) revealed a similar rate of loss (no significant difference at P-0.05) ex- cept for the middle region at 7 days after the application. Al- though not significantly different (except for 3 days after appli- cation) the rate of loss was highest in the top center region of the tree. This is probably a result of increased rates of photo- degradation and volatilization in this region. The effect of residue levels on the population distribution of European red mite active stages is presented in table 4. No significant difference (P=0.05) in the population distribution between tree regions was noted with either spray system, however, in the control the population level was significantly less in the top center of the tree after application was made to treatment trees. This may be due to the feet that this region would be less 42 Figure 5. — Mean tree residue (ug/cmz) of acaraben 4E as a function of time after spraying semi-dwarf Red Delicious apple trees with low volume and conventional spray systems. 43 5 .— Treatment 4 (A) Low Volume Spray System 02 (B) Conventional Spray System 9 <9 3 3 z m m 3‘: <2 2 o < I ‘4 A l H B O O 3 7 I4 2| NO. OF DAYS POST-TREATMENT .vaaauw m>oam a oo.m u< u .uaaaum m>anm a mw.H u< a .AHm>mH no.oumv uamummmav hauamuamwcmwm uaa mum umuuma caeaou m an amaaHHam aaaaao am>0m m aw mammz m 44 m ma m cm 9 nm on mm ammz mmuH : m mm m mm A am a we oumuamo : m mm m mm p cm on ma numuamo : m 0a m ma 9 mm no on nmanvwz : m mm m mm pm om m 0m aznmnafiumm ama00uam>aao m «a m mm mm om am no ammz mmuH : 0 00 0 00 00 00 0 00 . 0000000 .. 0 00 0 00 00 00 00 00 . 0000000 .. m mm 0 mm m mm m o0 nmavvfiz : m mm m am am mm m an nhumnafiumm maaHo> sag am «a n m sawmmm unmaummua mmua aawumaflana< nmum< mhma 0.05ma 0mm mash ca mmmuu madam maaaofiamn 0mm mumsvlaamm au mamummm hmuam Hmaafiuam>sou was maaHa> 300 he vmum>0Hmv uflmaamv me amnmumum Hmauaaw Baum mammuamv uamuumm I .m magma 45 .uaaauw m>onm a oo.m u< u .naaauw m>anm a mw.H u< n .A0m>m0 mo.oumv uamumwmwv hauammwm0amwm uaa mum umuumH aaaaau m up vmaaHHam menace am>0w m c« mammz m 00 000 0 000 0 000 00 ~00 000 00 000: 0000 = a 000 0 00 0 N00 0 00 0 00 0000000 : 0 N00 0 000 0 000 0 mm0 000 00 0000000 : 00 000 0 «00 0 00m 0 000 0000 000 0000002 : 0 000 0 000 0 000 0 000 00 00 0000000000 0000000 0 00 0 mm 00 00 0 00 00 000 000: 000a : 0 mm 0 mm 00 No 0 00 000 000 0000000 : 0 00 0 00 00 mm 0 00 00 000 0000000 : 0 00 0 mm 00 00 0 00 00 000 0000002 : 0 00 0 00 00 00 0 00 . 00 000 0000000000 000000000000 0 «a 0 00 00 mm m 00 00 000 0002 000a : 0 0m 0 00 00 mm 0 00 000 000 0000000 : 0 «a 0 00 0 on 0 00 00 000 0000000 0 0 mm 0 mm 0 00 0 00 0 000 000000: : 0 00 0 00 0 00 00 00 00 000 0000000000 0000o> 300 am «H n m unmaummuHImum scammm , unmaummua a00ummwaaa< umuw< mhmn mmua «mmH\Ammwmum m>0uumv mmuwa amp ammaauam ma umnaaz 0.0000 .00 0000 00 00 amnmumum ma maawumofiamem hmunm Hmnaaunm>aaa mam maaHa> 300 an vmuummwm mm mmmuu manna maafiowamn vmm mum3vI08mm a0 .Asuan Haas masmmdaamm .mmuwa emu ammaauam ma aafiuanfiuumwn I .q mHnt 46 environmentally protective. Both spray systems reduced the mite population in all regions through 14 days after application, however, the population then started to increase in the conventional treatment but continued declining in the low volume treatment. This is presented for the mean tree population in figure 6. Although the number of European red mites present 21 days after application is not significantly less in the low volume treatment when compared to the conventional treatment in table 4, it becomes significant, for all tree regions, when the control is removed from statistical analysis. A more realistic comparison of spray treatments, based on percent reduction in population rather than absolute numbers of mites present, can be seen in table 5. These data reveal that 21 days after application the low volume spray system effected a significantly greater reduction in mite population than that achieved with the conventional system. Although the low volume Spray system generally provided the advantage of increased deposit, this was realized as a severely non-uniform distribution characterized by minimal transport to the top center of the trees. The relatively uniform distribution achieved with the conventional spray system would be more desire- able, however, this was probably achieved as a result of "washing" the tree with a large volume of water in which a lower average de- posit is realized because pesticide is lost by water run-off from the trees. 47 Figure 6. - Mean tree population of European red mites in semi-dwarf Red Delicious apple trees as a function of time after spraying acaraben 4E with low volume and conventional spray systems. I75 ISO |25 N0.0F EUROPEAN RED MITES/ LEAF 48 \ Treatment (A) Control (B) Conventional Spray System (0) Low Volume Spray System 75 " 50 - -B 25 ’ —C 0 j l l 1 Precount3 7 l4 2| NO. OF DAYS POST-TREATMENT 49 .0aaouw 0>o0m a 00.m u< 0 .0cao0m 0>o00 a mm.0 0< 0 .A00>00 mo.oumv 000000000 h000000m0cw0m no: 000 000000 0o5800 m 00 003o00om 085000 00>0w a 00 00002 a 00 mo 00 m0 0 0m 00 mm 0002 000a. : 0 no 00 mm 0 mm 0 on 0000000 : 00 00 0 00 00 0n 00 N0 0000000 : 00 we 0 N0 0 0m 00 no 0000002 : 00 00 00 00 0 mm 00 00 0000000000 000000000000 0 mm 0 0m 0 m0 00 00 0002 000a : 0 mm 0 on 00 mm 00 m0 0000000 : 0 mm 0 ow 00 no _ 0 00 0000000 : 0 mm 0 0m 0 00 0 00 0000002 : 0 mm 0 mm 00 no 0 mu 0000000000 0800o> 3o0 0m 00 0 m 000wmm 000800008 0008 0o000000na< 0000< 0009 0.00m0 .mm 0050 so M0 00000000 mo 000000000000 00000 0mao0uam>noo 0am 0850o> 300 00 00000000 00 00000 00mmm 090000009 00m 00030 10500 00 0000009000 0000 000 ammmounm mo Aussoo 000800000I000 aoumv 000005000 0000000 I .0 00009 50 'The Effect g£_Air'Ve10city, Sleeve Spin Speed and Ratio 2£;Liguid ProportioniggdtgnglBeeCOmist Sleeves gg'The Spray DiStribution ' ’DeliVered by _a_'_‘Low'Volume 'Spray'SjLstem. The effect of air velocity, sleeve spin speed and ratio of liquid proportioning to 2 sleeves on dye distribution is presented in table 6 and figures 7-10. In general as the air velocity is increased, the deposit de- creases in the near region of the tree while increasing in the side, center and far regions. The difference in regional deposit as a function of air velocity, however, was usually only signifi- cant (P-0.10) for the 2 extreme air velocities. It is believed that as air velocity is increased, the peripheral (near) foliage is deflected to a greater extent which allows more spray into the tree canopy. This belief is also held by Hall gt 21° (1975) and Randall (1971). It is believed that an increase in air velocity also provides for more efficient impingement of available spray droplets within a region. A greater reduction in dye deposit occurred as the spray moved from the near to the center region of the tree (77% average) as compared to the equivalent distance from the center to the far region (53% average). A greater deposit was achieved at the slower sleeve spin speed although the difference was significant (P=0.10) in only 9 of 48 comparisons. Table 17 reveals that a larger droplet size is pro- duced at the slower spin speed which could result in the increased deposit through more efficient impingement. Whether or not the in- creased deposit provided by larger droplets is advantageous would depend entirely upon the situation encountered. For example, in 51 .000>00 00.0000 000000000 0000000000000 000 000 000000 008800 0 %0 00300000 080000 00>0w 0 00 00002 0 000 0m.0 00 000.0 00 005 00 No.m 000 00.0 000 00.0 0000 mm.~ 0 mo.m M00 : m 000 mm.o 0 0m.0 0 mw.m 00 0n.m 00 Nu.o 000 0m.0 00 00.N 00 mm.m 000 0.00 Mm 00 0~.o 000 no.0 000 00$ 00 m0.n 00 om.o 00 00.0 000 2.0 00 0m.m mm0 : m 000 00.0 00 om.0 00 mm.m 0 00.0 0000 «m5 000 3.0 0000 0.0.0 000 00.0 000 m.mm m 0 00.0 00 2.0 00 No.0 00 00.0 0 00.0 0 3.0 0 00.0 000 00.0 $0 : W 000 3.0 0000 3.0 000 3.0 00 mm.m 00 0m.o 00 0m.o 0000 3.0 00 own 000 0&0 m 00 00.0 000 ~m.o 000 00.0 000 00.0 000 mm.o 00 0N.0 00 No.m 000 no.0 mw0 .. 00 0 05.0 00 00.0 000 0m.m 000 00.0 0 00.0 0.00.0 0 w~.m 000 mn.m 000 x 0.00 MW 000 mm.o 00 00.0 000 m0.N 000 mm.q 0000 00.0 000 00.0 000 0m.~ 000 «0.0 m00 .. mm 00 3.0 0000 mmé 000 no.0 00 m0.n 000 006 00 00.0 0 00...” 000 00.0 000 m.mm m 00 00.0 0 3.0 0 m0.0 0 om.m 00 «00.0 00 wm.o 00 0m.0 000 3.0 $0 : m 000 00.0 00 0.0.0 000 m0.0 000 3.0 0000 «0.0 000 00.0 00 00.0 0 00.0 000 «.mm m 000 000000 0000 0002 000 000000 0000 0002 A0\0v 00\80 0000000 0>o00 8 00.mv 000000 0008 0000000 0>o00 8 mw.0v 000000 0009 00000 0000 0000000> 0~80\wav 0000000 00000000000 0>000m 000 0.00>0000 N 00 0000000000000 000000 00 00000 000 00000 0000 0>0000 .0000000> 000 50 00000000 00 00000 00000 000000000 00% 0003010800 00 .800000 h0000 0800o> 300 0 m0 0000>0000 .000 00 000000000000 000 I .0 00000 52 Figures 7 and 8. a The effect of air velocity and sleeve spin speed cu: the distribution of dye, delivered (equal sleeve delivery) by a low volume spray system, in semi- dwarf Red Delicious apple trees. 60>»; >._._oo..w> E4 0 M 0.3 0.00 0.00 0 0- 000 .00 00 .00 % 0:390 0>00< 00.0.2 00.. 3.66 Meters Above Ground 54 (awn/fin) llSOdBO 3A0 fs/ :0 ._._oon_m> m=< fly; 00, I" \NII\% %% e . “@mtwreuwu wk % At. em W e. 9596 96.3 8322 mm. ¢.NN ”Y. % w 35 >.:oo._m> ma M 5% 0mm tum ‘3}. \§‘§ I r \$\\. ‘ J \ ‘32? \% mN-%\% 5%" I %-\,. MGR, X \ms Wu. 9.». it % U39 0254 wbmfioi @Ofl 58 the control of diseases or relatively sessile arthropod pests, it may very well be more advantageous to produce a greater dr0p1et density, provided by smaller droplets, at a small sacrifice in spray deposit. 0n the other hand, if a highly mobile pest is the target the higher droplet density may not be required and deposit could be maximized with larger spray droplets. Deciding on the proper droplet size for a given situation is not as simple as pre- sented above however, and must involve consideration of the method of application, the target crop, environmental conditions, as well as the pest organism. The delivery of 2/3 of the spray volume through the top sleeve resulted in a reduction of dye deposit in the bottom half and an increase in the top half of the tree except for the far region. Except for 2 instances, however, the differences were not signi- ficant (P-O.10). Table 7 represents a simulation of dye distribution as would be expected to occur from 2-sided spraying using the data acquired (table 6) in which trees were sprayed from one side. These data reveal that the most uniform distribution of deposit (least differ- ence between tree regions) occurs at the highest air velocity, es- pecially at the lower sleeve spin speed. In comparing tree mean deposit for different air velocities at the same spin speed, no significant difference is seen except between 22.4 and 44.7 m/s at 183 r/s for equal sleeve delivery. No significant difference in tree mean dye deposit occurred as a function of delivery proportioning 59 .AHm>mH on.oumv uamummuse snucmufimsamam nos one penned soaaou n .An vosoflaow agaoo cozw m a.“ memo: m muons mm.m no ow.~ on mm.m onm on.H m mq.m mmn .. mm m mmé o 0&6 no «an one mud n mm.m 03 5.3 m one H~.m non 0H.~ no 38 ns 34 m 36 mwn : m m «N3 on .35 v 3.5 can nmé one moé oon m.mm m as so.“ as 24 an as a :6 an «as m: .. m mono mo.m nuns cm; on $6 nm mo...” no 8.0 OCH «.2 m ocon o<.m .onm mm.n onm no.< no N¢.N one oo.< me .. MW mo 00..» no mm.~ on «in o 36 one moé con “:3 m vunm can” no 34 one mmé non om?” nm 003 mwn : m mom 8..» one 34 on 056 on Nmé won omfi oon m.mm m m $.N m om.o m mn.m nm 34 one mwé m3 : W mono $5 nm 34 on .36 one corn v mmé ooa «.2 m new: woke. Housoo humnnwnmm “mucous humnmfiuom Am\uv Am\av canon» m>onm a oo.m unsoum o>onm a mm.H vwmmm swam huaooao> Amao\wsv unmonon saoommuosam o>omam “H4 m.Ao mannuv mmouu mamas meowuuaon com muvaI«Emm mo ovwmla on chfiumuanamm momma oasao> 30H scum snow magma waahmunm wovamlu kn noncommo mm aowusnauumfiv mun voumasaam I .n manna 60 when comparing the same air velocity and sleeve spin speed. It appears that the variables of air velocity and ratio of delivery proportioning do not have much influence on the average dye deposit but rather influence how the dye is distributed throughout the tree. Which variable condition.would be most de- sireable would depend on the nature of the tree being sprayed as well as the pest distribution within this tree. Analysis 2; Spray Distribution Delivered From Each (2) Beecomist Sleeve 22mg Low Volume Spray §y8tem. The distribution of dye in a semi-dwarf Red Delicious apple tree as delivered by each Beecomist sleeve is presented in figure 11. The bottom sleeve was responsible for most of the dye deliv- ered to heights of 1.22 and 1.83 m in the tree, whereas most of the deposit encountered at the 2 highest elevations was delivered by the top sleeve. If one compares tree regions at a given height, however, a more representative picture of spray pattern can be seen. Dye delivered by the bottom sleeve was found in 10 of the 12 same pling regions, whereas only 7 of the regions contained dye deliv- ered by the top sleeve. For some unexplained reason a very low level of transport into the center of the tree was achieved. It would appear that a sub- stantial portion of spray from the top sleeve, which passed through the near region, was transported over the top of the tree above the center sampling region. These data indicate that more efficient spray transport to semi-dwarf trees might be achieved by lowering 61 Figure 11. .. The distribution of dye in a semi—dwarf Red Delicious apple tree as delivered by each (2) Beecomist sleeve on a low volume spray system. 62 TI E a~.~|v_A|e a~.N||lv_ .13! 3 ll g: _ mass \ . 9:5. as... . is. . a. .2. a: in: z: .5".— ts. a a .3... J. \. a O I O y SN «8 8 N s. s . m. a a 3.. .u a: x. .a H... .... M .. as. E. a . . was. a a... was: s. a. no .. 8.. E. a a. . 2.8... .2. 5.3% as a I a...» .\ 3N3: <3:ch “:ch .8: .LHK. \ 70.. i. . , in... . ». ... Er .. . ‘ .‘ «2. . _.. II 63 the tap sleeve and channeling the air stream to make the spray pattern more compatible to the smaller size tree. The distribution of dye in a wooden spray stand (Fig. 12) verifies that a substantial amount of dye from the top sleeve was transported above the center tree region at 3.66 m. In fact, the dye deposit (from the top sleeve) in the center region is slightly greater at 5.49 m than at 3.66 m. One can also clearly see the expanding spray pattern as de- livered by the bottom sleeve. This sleeve delivered over twice as much dye as the tap sleeve to the far side of the stand (5.49 m from sprayer) at a height of 3.66 m. This occurrence is also seen in the semi-dwarf tree mentioned above. This helps to explain why a slight reduction in dye deposit occurred in the top far side of the tree when 2/3 of the spray was delivered through the top sleeve in the previous study. By proportioning more liquid to the top sleeve, less is available to the bottom sleeve which is res- ponsible for most of the spray transport to the far region at 3.66 The use of a wooden spray stand in spray distribution studies can yield valuable information concerning spray patterns from par- ticular nozzle arrangements in order to maximize pesticide trans- port to a given size (height and diameter) tree. Comparison 2: Dye Distribution Delivered by_Low Volume and Conven- tional'§pray'Systems EQJSemi-Dwarf and Standard Size Red Delicious Apple Trees. The distribution of dye in semi—dwarf Red Delicious apple trees as delivered by both spray systems is presented in table 8 m. 64 Figure 12. — The distribution of dye in a wooden spray stand as delivered by each (2) Beecomist sleeve on a low volume spray-system. 65 ENN. EmQ. EVEN Ean Emtn 4 . . 3.2.5.3 . Te .8 .IV mm. 2. m. 20:8. cu ow cum. new. 86me notes. m... n. 2.8 0mm 2.... can own an.“ so .3 am... .vmm. «0.. ohm. on.» MEN .vS. 00.. 2.0 nm..v. .m. +¢¢.. 00.0 2.6 mun and T :53 Illa-Illegall— 66 and figure 13. Although no significant difference (Pa0.05) in deposit between the spray systems was noted, except for the side region (1.83 m above ground) and the near region (3.66 m above ground), a greater reduction in deposit as the spray moved through the tree is observed with the low volume spray system. The distribution of dye in standard size trees (table 9, fig- ure 14) delivered by both spray systems reveals that the low vol— ume spray system delivered significantly (P=0.05) less dye to re- gion A (near) at 1.83 m and 5.49 m above ground, yet slightly more (not significant) than the conventional system to this region at a height of 3.66 m. The lower deposit at 1.83 m is probably due to the fact that 2/3 of the spray volume was delivered through the top sleeve which is transported in greatest quantity to a height of 3.66 m. The lower low volume deposit at 5.49 m (region A) is believed to be due to the short horizontal spray travel distance (from sprayer to tree) which is not sufficient to allow the expand- ing spray pattern from the top sleeve to reach this height. This is not a severe problem with the conventional spray system because the spray droplets are dispensed in this direction under hydraulic pressure, whereas the spray droplets from the Beecomist sleeve are dispensed perpendicular to the air stream and must be turned by the air stream to be transported to the tree. By the time the spray pattern has traveled the horizontal distance required to reach region C (center) at 5.49 m above ground, sufficient expansion of spray pattern from the top sleeve has 67 .AHe>eH mo.onmv unopeMMfip hauseofimwcwfim nos one weapon eoEEOo e zn wosoaaom enema %s¢ e .mem ne.m one me.n we so.~ we me.m we as.~ nu n¢.o one me.n we om.m Hmaosuempcoo w Hm.m one w~.n no mH.N n mm.q on cm.a e no.0 ne am.o we qo.m essHo> Son Anv oowm on new Amv neuaeo A4. ueez Aav eofim no. new Am. Hoodoo Aone E no.mV aofiwom eoue Aossouw e>one a mw.Hv mafiwem eeua Amao\msv uamoeen emn e.wmoa .oa umawn< so eeeuu mange maogofiaen vex «pesoIHEom ou maeuehm meuem HeGOfiuso>coo one oEdHo> 30H en wouo>HHoo who no sofiuanwuumfio one I .m wanes 68 Figure 13. - The distribution of dye in a semi-dwarf Red Delicious apple tree as delivered by low volume (A) and conven- tional (B) spray systems. A = Near B = Center C = Far D = Side 69 r 5 4 3 2 nl £228. :8me we I83 HEIGHT ABOVE GROUND (m) {‘1‘ D . oooooooooooooooooooowo“one 999000 wowowowowowowowowowo. u§§§§§&&&&.mw 3 U “J““““ D OCOOOCOIOOOOOOOOOOOJ. FEIGHT ABOVE GROWD (m) P P 4 3 2 .l 0 £298. 588 we 70 .aoum>m henna Hesowuco>soo o .aoum%m menom oeoao> 304 n .Ane>en mo. oumv uneuemmwv hauseo«Mficwfie no: one weapon soaaoo e an oesoanom mseoz >s< e IIIIIIII a; ha.~ pm mm.o IIIIIIII pm me.o IIIIIIII as mn.m ms.m IIIIIIII we so.m am ae.o IIIIIIII pm ~m.o IIIIIIII new Hm.n can um.o eh HH.¢ am sm.o m mH.o pm mm.o mes mm.o as mo.s oe.m pm o~.o ume am.n pm os.o m nH.o am an.o pm oe.o H NH.m am mm.o he me.m pm o~.o as s~.o pm am.o one no.0 “somm.m mm.n pm ms.o em Ne.H am s~.o an -.o one aa.o meg sm.o empnm.~ Auneeazumefim. Amesmv Anew. Amaeeaznumm.AumucmuVAuHeeaquemz. Anemz. .5. o m m a o m < easouu «some unwamm cowwem mesa Amsoxmsv uwmomen ohm e .wnaa .ma umswad so eeouu eaeee esofiowaea tom mean ouevseue on maeuehm heuoe Heaowusepsoo one oasHo> son kn oeue>waeo ozo mo nowusnauueflo one I .m oHneH Figure 14. - The distribution of dye in a standard size Red Delicious apple tree as delivered by low volume (A) and convention- al (B) spray systems. = Near = Near-Middle Center Far-Middle Far Side Side-Middle communes» Illl 72 A . 5 . A * P b h 4. .3 2 I. .2903. :8er as 3.66 A . 3.66 " I38 ‘ . 4 3 .2062 .388 25 Height Above Ground (m) 73 occurred resulting in no significant difference in deposit between spray systems. The effect of spray pattern expansion from Beeco- mist sleeves on deposit can clearly be seen by comparing the de- posit at 3.66 m and 5.49 m for regions C and F, both of which are equivalent horizontal distances from the sprayer. The greater de- posit (although not significant) at 5.49 m for regions C and F is believed to be due to the fact that the bulk of the spray from the top sleeve has passed above these regions by the time the same horizontal distance has been traveled at 3.66 m. A simulated, 2-sided spraying, deposit (table 10) reveals that no significant difference (except for standard trees, peri- phery region.at 5.49 m) occurred between spray systems in the de- posit obtained in a given region for a given tree size. A drastic difference in deposit (with both spray systems) was noted in the center region at 3.66 m when comparing both tree sizes. The signi- cantly lower deposit in the standard size tree is believed to be due largely to a denser foliage canopy and the greater travel dis- tance required to reach this region in the standard size tree. The reduced deposit in the center regions of the standard size tree is the major factor contributing to a mean tree deposit that is significantly less than that achieved in semi-dwarf trees with both spray systems. Although the mean tree deposit was 44-47% less for standard size trees as compared to semi—dwarf, no significant diff- erence between spray systems for a given size tree was discovered. The above data reveals that efficient spray transport to apple 74 .Ano>oH 00.0umv uaouommww AnuceoHMfiawao uo: one HouuoH coeaoo e %n oo3oaaom mceoa ma< e o0 mm.~ one 00.0 mo ~0.m ne 0n.0 nan 0H.m one 0H.H wwo 05.0 : nesowuso>sou 0o ma.~ ne m0.0 0o 00.~ e «m.0 he mm.m one 00.H o0 on.~ oueoaeum ossao> son new cm.e IIIIII IIIIIIIII has m~.m has so.n we Hm.~ new oa.e : Hmaosuao>coo new ma.m IIIIII IIIIIIIII new m~.s a mm.e eon wa.n woo mo.m nonsensemm manno> son seoz ooua Hoodoo kuonewuom nousoo zuoneauom Housou huonofiuom ouwm ooua ucoaueouH ocsouw o>one 8 00.0 wasouw o>one a 00.0 vasouw o>one a m0.n mmao\mwv naeomon «N0 e.eoouu onoee osoaowaon vom a0 oHneuv oufio oueoseuo one A0 oHneuv muesolaaoo mo oowo H cu escaueoaneee heuoo Heaoauao>coo one oanao> sea Bonn eueo wage: wauheueo powwolm hn wouoomwo oe coauanfiuuowo oho ooueanaam I .0H onnee 75 trees must involve a consideration of tree height, diameter and foliage density so that spray nozzles can be positioned, and pest- icide rates adjusted to achieve sufficient coverage for effective pest control. Spray Droplet Spectra Analysis of §_Conventiona1 and Low Volume Spray System as Determined in Open and Foliage Environments With a_Drop1et Impingement Harp. The percent number of dr0p1ets and volume of spray in various droplet size classes for a conventional and low volume spray system as determined in open and foliage environments is presented in tables 11 and 12, respectively. The low volume spray system pro- duced a much narrower, small-droplet, spectrum as compared to the conventional spray system. For the conventional spray system, droplet distributions which passed through foliage contained a greater proportion (by number and volume) of droplets in smaller size classes than those obtained in an open environment. The largest droplet caught in an open en- vironment was 584 um, whereas in a foliage environment no droplets larger than 437 um were encountered. This same filtering effect of a foliage environment on spray spectra was reported by Reichard ggngl. (1978), using an optic probe for droplet sizing. The increase in percent volume in smaller droplet size classes, of spray passing through foliage, is not due so much to greater numbers of small droplets but rather to a lack of large droplets which contribute greater volume percentages. Because the large droplets are not as prevalent in the foliage environment a greater percentage of the .Ae o~.m so moaeomHu "a mm.H so “seams. mwmsnoo :H 0 .AB 00.m mo ooseuowo we m0.n mo unwwonv coeo sH n .Axaeoeoo muso>nom oawuo>aozv onenenunm quooan e 76 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 000 I H00 H.0N 0.H 0.0a 0.0 0.0 «.0 0.0 0.0 m.m N.0 0.0 0.0 0.0 0.0 0.0 0.0 000 I Hoe ~.mH m.m 0.0a ~.H 0.0a 5.0 0.0 0.0 0.0m m.H 0.mm 0.0 0.0m 5.0 n.5H «.0 000 I nom 0.5N 5.0 n.0m «.0 0.- ~.N 0.0m 5.0 0.0m 0.~H m.~m ¢.m 0.Nm m.m n.0m N.H oom I How m.mm «.mm N.m~ e.HH 0.0m 5.0 m.mm n.~ 0.m~ 0.Hq m.q~ m.H~ H.m~ «.mn q.m~ H.m 00m I Hon m.0 H.nm 0.HH 0.0m 0.0a c.0m 0.Nm H.mn e.m 0.00 0.0 0.05 m.mn 0.~0 0.0a om.mm 00H.I 0- 0.0 0.0m 0.H 0.0m 0.~ 0.00 H.m n0.mw oabno> N nonasz N oeano> N uonsbz N oasao> N nonssz N oaaHo> N Honssz N A830 Hoouw omoasaeum a: on Hooum mooneaeum a: mu Hooum mooHaHeum a: ma souewdSH an m ooeao oefim Auouoeeanv onwm ouw3 muoHeoun .euen usoaownaoaw uoaeoup e no“: mucossouw>so oweanom one _ some aw posfiauouop me souemo xenon Hecoauso>soo e now ooauouueuo uoHoouv emeuem I .HH oHneH .Aa 0~.m mo ooseueno “a 00.H mo unwfionv oweHHom nH o .A8 00.0 no ooaeumfio “a mw.H mo unwfionv eoeo sH n .A0seeeou ouco>aom oefiuo>nozv oueaenunm axuoofin e 77 h.~ 0.0 0.0 0.0 OOH I 00 0.0 0.H 0.N «.0 0.00 0.NH 0.00 0.0 00 I H0 0.00 n.0H 0.00 0.0 0.00 H.00 0.00 m.H0 , . .. 00 I 0N 0.00 0.00 0.00 N.H0 0.0 0.0m H.0 o0.00 0N I o ~.m .18 m... and 053, N been... N 2.32, N amps... N 33 Hooum omoaafieum s: 0H soumwdaa as 0 mmeao ouflm Auouoaewnv oefim ones uoaeoun .euen usoeowafieaa uoHeouv e nuns ousoasoufi>so oweaaom one soeo Ga vocaauouoo me aouoho henna oasao> son huwoouoe nodaouusoo e you ooauowueue uoaeouo emeuem I .NH oHnee 78 spray volume is occupied by small droplet size classes. At an air velocity of 11.6 m/s (at 3.05 m), no droplets larger than 375 um were obtained on 5 um tungsten wire. Of a total of 1966 dr0p1ets measured (in the open) on this size wire only 14 were discovered between 301-400 um. Under the conditions tested it is believed that the 50 um wire was of sufficient size to cap- ture the largest droplet delivered by the conventional spray sy- stem. This belief is based on the fact that only 3 droplets were obtained with the 50 um wire that were larger (by 5-32 um) than the largest droplet obtained with the 25 um wire. With the low volume spray system very little difference in the droplet distribution encountered in open and foliage environ- ments was observed. The largest droplet obtained in the open and foliage environments was 91 and 78 um, respectively. Under the conditions tested it is believed that the 15 um wire did catch the largest droplet produced by the low volume spray system be— cause only 2 droplets were caught which were larger (by 3 um) than the largest size obtained with the 5 um wire. The data suggests that smaller droplets would be more.efficient pesticide transport agents into inner foliage habitats. The results obtained are believed to be due to the tendency of small droplets to follow the air flow pattern around obstructions rather than im- pinging on the first obstacle in their path, as is frequently the case with large droplets. Although small droplets may be more efficient transport agents into foliage microhabitats, the efficiency 79 of deposition would depend upon dr0p1et velocity, target config- uration and environmental conditions. Studies 22 The Parameters Which Affect Spray Spectra Characteris- tics From‘Rotarnyleeve Nozzles. A. The Effect of Sleeve Construction, Rotational Velocity and Sprayer Air Velocityq g Droplet Spectra. Table 13 presents droplet size statistics for spray distri- butions delivered by various Beecomist sleeve types under differ- ent operating conditions. The individual spectra are presented in their entirety in figure 15, whereas the spray spectrum from 2 Beecomist sleeve types is illustrated in a 3-dimensional form. in figure 16. The terms D10, D50 and D90 in table 13 represent cut-off points (in droplet sizes) on the abscissa at which 10, 50 and 90 percent of the volume has been accumulated. The difference between D10 and D90 is used as an index of the spectrum's width. From the data presented it can be seen that porosity and con- struction has very little effect on the droplet spectrum produced by porous sleeve types. These findings are in agreement with in- formation presented by Schmidt (1967). Even the perforated stain- less steel sleeve produced spray spectra quite similar to the 3 porous types, except that the spectra are a little wider, and the D50 values are higher for the 2 high sleeve velocities but not for the low one. Of the porous sleeve types, the stainless steel produces a droplet spectrum that is slightly narrower than the polyethylene, 80 Table 13. - The effect of sleeve construction, rotational velocity and carrier air velocity on the aqueous droplet spectrum delivered by Beecomist sleeves.a’ ’c’ Air Sleeve Droplet Diametere (um) at Cumula- Sleeve Type Velocity Velocity tive Percentages of Spray Volume (m/s) (r/s) D10 D50(VMD) D9O D90-D10 20 um stainless steel 22.4 50 299 349 422 123 n u n n 100 142 191 264 122 " " " " 183 56 98 157 101 n n n 44.7 50 253 406 485 232 n n " " 100 167 209 282 115 n n " " 183 57 93 135 78 60 um stainless steel 22.4 50 276 333 390 114 n n " " 100 136 196 263 127 " " " " 183 58 101 159 101 " " " 44.7 50 243 363 457 214 n H " " 100 152 200 283 131 n n n .u 183 57 91 136 79 70 um polyethylene 22.4 50 190 319 420 230 n n " 100 110 173 250 140 n u " 183 52 98 160 108 " " 44.7 50 243 345 443 200 n n " 100 134 '193 285 151 n n " 183 49 85 137 88 perforated stainless steel 22.4 50 182 299 416 234 n n " 100 123 198 283 160 " " " 183 57 112 204 147 " " 44.7 50 198 309 410 212 n n " 100 141 205 281 140 n H " 183 68 115 214 146 : Beeco Products Company. Operating parameters: delivery rate (1 sleeve) = 6.7 ml/s; Optic probe distance = 0.91 m; optic probe height = 1.37 m. c Environmental conditions: temperature range = 21-25°C; RH range = 37-42%. d Surface tension = 72.8 dynes/cm at 24°C. e 115 um of reported values. 81 Figure 15. - The effect of sleeve construction, rOtational velocity, ~ and carrier air velocity on the aqueous spray droplet spectrum delivered by Beecomist sleeves. PERCENT VOLUME 43 39 ALA- LA 20 AlAAAALLu—LIAA 10 10 L 40 ALL AAAJJ 20 ALLA- J.-..... 40 AALL“.L1 82 to mountm rm STRIKE“ am can! ' tvv“ '0 01mm PM 8701‘!“ em 11"! I 10 museum 9'” mama-t m mm "mm "Ill. m . IrIu IPIED nIa erocIIv 31 um) III/II : Ito zzus 103 com Inn to“. C) I” 8‘0. N so 11.0 00 IALALAAALALALIALLAL-‘ALLLA A 100 200 300 400 soo soo DROPLET DIRMETER (NICROHETERS) 83 Figure 16. — The effect of sprayer air velocity and sleeve rotational velocity on the aqueous spray droplet spectrum delivered by 2 Beecomist sleeve types. Droplet size (volume median diameter) is indicated on the vertical axis, and the width of the droplet spectrum (Dgo-Dlo) is indicated by the relative width of the blocks. 84 (uni) JaIawoga uogpaw swnIOA not. 3on sum EEoooom rV mm. 00. On 4. \\ \\ . .\ \.|. 260.0 23.23on «neon. 532.0 33.0 .36 26.520 00.2230 «4 85 except for an air velocity of 44.7 m/s and rotational velocity of 50 r/s. This exception may have resulted from poor sampling in which the larger droplets delivered at 50 r/s may have caused a more rapid liquid build-up on the sampling tubes which was blown by the sampling window as random large drops by this higher air speed. The differences between stainless steel and polyethylene decreased as the rotational velocity increased. This relationship occurred with all rotational velocities at an air speed of 22.4 m/s and for rotational velocities of 100 and 183 r/s at an air speed of 44.7 m/s. The rotational velocity of the spinning sleeve has a signifi- cant effect on the droplet spectrum produced. In all cases, as the rotational velocity of the sleeve is increased, the D50 of the spectrum decreases. The width of the spectrum (Dgo-Dlo) also de- creases, except for the 60 um stainless steel when going from 50 to 100 r/s at the low air velocity. In figure 17, the change in VMD occurring as a result of in- creasing the air velocity from 22.4 to 44.7 m/s is plotted against 3 rotational velocities for each sleeve type. These data indicate that there is clearly an interaction between sleeve rotational vel- ocity and the difference that occurs in VMD between the 2 air vel- ocities. The difference in VMD that occurs with increasing air velocity decreases from a positive value to a negative value as the rotational velocity increases from 50 to 183 r/s. In figure 18, the droplet spectrum of a 20 um stainless steel 86 Figure 17. - The effect of sprayer air velocity on volume median diameter (VMD) at 3 rotational velocities for 4 Beecomist sleeve types. W104”! II/s _ VHDu.‘ ms 0 A -10 20 87 SLEEVE TYPE ._——_. 20 HICROHETER POROUS sraquess STEEL ,____. so HICROHETER POROUS STRINLESS STEEL x____. 70 HICROHETER POROUS POLYETHYLENE .___4. PERFORHTED srnINLEss STEEL I T fi 1 I I 50 100 150 200 SLEEVE SPIN SPEED (R/S) 88 sleeve is plotted as percent number of droplets as a function of droplet size. When droplet number is considered rather than spray volume, the spectra take on a bimodal characteristic which is par- ticularly pronounced for the 2 slowest rotational velocities. Analagous spectra for each of the other sleeve types show this characteristic, though this phenomenon is less pronounced for the perforated sleeve. Comparison of figures 15 and 18 shows that the left hand peak of a droplet number spectrum contributes very little to the volume of the total spray, and that the right hand peak is the one that is shifted by changing sleeve rotational velocity. In figure 19, the aqueous droplet spectrum delivered by a 70 um polyethylene sleeve is compared with that produced by several typical hydraulic and one pneumatic type nozzle. Of all the nozzles tested, the spinning sleeve nozzle produced the narrowest, smallest droplet spectrum. The operational characteristics of variable VMD and narrow- ness of droplet spectra relative to other commercial nozzles would seem to make the Spinning sleeve sprayhead an attractive candidate for both droplet size/efficacy studies and future prescription spray application programs. B. The Effect g£_Flow Rate on DrOplet Spectra. As the delivery rate is increased with both sleeve types tested (table 14) the spray droplet size is increased as well as the width of the spectrum (D90'D10)' This could be a result of the intrinsic effects of delivery rate on the droplet formation mechanism, a 89 Figure 18. - The effect of sleeve rotational velocity and sprayer air velocity on the percent number aqueous spray dr0p1et spectrum delivered by a Beecomist 20 um porous stainless steel sleeve. 90 000 Ammunmzomunz. mwpmcho qumomo 00m 000 a... ecuu 0.00 ¢.NN 0.00 Q.NN ~0\:0 >hu004~> cu: 00¢ 00 00 can 00“ no— no— n0\¢. awumm tuna 000 00n YTTYY ""Tj‘IjV US VYTVVV 01 DZ 08 HBQNHN 1N3383d Of 91 Figure 19. - Aqueous spray dr0p1et spectra delivered by various nozzle types. Operating Conditions: Beecomist: carrier air velocity - 33. 5 m/s. sleeve rotational velocity - 183 r/s. delivery rate = 6.7 mlls. distance 8 0.91 m. Spraying Systems: pressure 8 14.1 kg/cmz. distance = 0.61 m. Kinkelder: dial setting = 80. PTO = 9 r/s. distance = 1.1 m. FMC No. 3 Disc, No. 2 Core: pressure distance FMC No. 5 Disc, No. 3 Core: pressure distance - 14.1 kg/cmz. = 0.61 m. - 14.1 kg/cmz. - 0.61 m. 92 .mmmemzomQHZ. muemzcao .unaomo 000 000 00¢ 000 00w 00n PPbPPvaPP—PppPperPk P—prpr ‘I MES m .2. 82° m .oz 8.... To 2.8 N .oz .029 n .92 8:... I 6352; I 5.00 mm .02 .003 0 .02 .0:u.—0>0 02:05.0 I Sumnm uzun>rhm>400 009.00 muhmzoxuuz 00 ”pun—Sumac I unf— NANNoz firITVT‘VTT‘ITYYYTTT‘FTITww111111]IIIY‘TYVT TC) 01 DZ 08 or END-IDA 1N3383d 93 Table 14. - The effect of delivery rate on the aqueous spray droplet spectrum produced by 70 um polyethylene and perforated stainless steel Beecomist sleeves.39bacgd Delivery Droplet Diametere (um) at Cumulative Sleeve Type ‘Eggg’ Percentages'ofg§pray Volume (ml/s) D10 D50 (VMD) D90 D9o-D1o 70 um polyethylene 1.7 44 80 113 69 " " 6.7 51 90 138 87 " " 13.3 57 100 173 116 " " 26.7 70 127 241 171 perforated stainless steel 1.7 52 99 180 128 " " 6.7 57 109 204 147 " " 13.3 69 120 214 145 " " 26.7 87 167 285 198 a Beeco Products Company. Operating parameters: carrier air velocity 8 33.5 m/s. sleeve (1) rotational velocity - 183 r/s. optic probe distance - 0.91 m. optic probe height - 1.37 m. Environmental conditions: temperature range - 23-24°C. relative humidity range 8 39-44%. Surface tension = 72.8 dynes/cm at 24°C. £15 um of reported values. 94 result of increased in-flight coalescence caused by increased par- ticle density (number of droplets/volume) in the air, or a combin- ation of both factors. C. The Effect g£_Two Sprayheads 22 Droplet Spectra. The occurrence of in-flight coalescence in a zone of spray pattern overlap from 2 sleeves is shown in table 15. The path of a droplet from the time it leaves the sprayhead to the time it lands follows an arched trajectory that is influenced by several factors. Because spray droplets are dispensed from the Beecomist sleeve in a direction perpendicular to the air stream flow, the initial arch of the flight curve is determined by the centrifugal momentum of the expelled droplet and the entraining force of the air stream. Once entrained, the droplet is carried. in a direction parallel with the air flow until the force of gravity exerts an influence greater than the diminishing horizontal drop— let velocity. If two sprayheads are placed close enough together in the air stream their patterns would overlap at some distance resulting in a greater density of droplets in the overlap area. If in-flight coalescence occurs, droplet sizes in a zone of spray pattern over- lap should be larger than in non-overlap areas. At a distance of 0.91 m, for both delivery rates, droplet size at the intermediate height (2.13 m) is larger than the other 2 heights (1.37 and 3.05 m). By looking at figure 12 one would expect significant spray pattern overlap to occur at this distance and 95 Table 15. - The effect of delivery rate, and sampling height and distance on the aqueous spray droplet spectrum produced by two Beecomist perforated stainless steel sleeves.39b9°»d Distance From Droplet Diametere (um) at Cumulative Delivery Rate Lower Sleeve Height Percentages of Spray Volume (ml/s/sleeve) (m) (m) D10 D50(VMD) D90 Dgo-Dlo 6.7 ' 0.91 1.37 72 125 236 164 " " 2.13 91 144 235 144 " " 3.05 74 127 241 167 " 3.05 1.37 72 122 219 147 " " 2.13 70 123 259 7 189 " " 3.05 72 126 216 144 17.8 0.91 1.37 75 137 253 178 " " 2.13 99 160 262 163 " " 3.05 81 144 259 178 " 3.05 1.37 80 135 243 163 " " 2.13 79 137 229 150 " " 3.05 84 138 236 152 a Beeco Products Company. b Operating parameters: carrier air velocity - 33.5 m/s. sleeve (2) rotational velocity = 183 r/s. c Environmental conditions: temperature range = l7-23°C. relative humidity range = 46-63%. d Surface tension 8 72.8 dynes/cm at 24°C. e $15 um of reported values. 96 height. At a distance of 3.05 m it doesn't appear that a signifi- cant region of in-flight coalescence was detected. This may be due to the fact that the zone of spray pattern overlap at this dis- tance passed slightly above the highest sampling height (3.05 m). By again referring to figure 12, however, some overlap should have occurred at this position. As would be expected, the percent in- crease in droplet size in the intermediate height is greater for the higher delivery rate. This is because the droplet density would be greater at a higher delivery rate thus offering more poss- ibility for in-flight coalescence. D. The Effect of Formulation 22 Droplet Spectra. Because low volume applications utilize high concentrations of pesticide formulations in water, it might be expected that these formulations would greatly influence the spray droplet spectrum produced. Table 16 reports dr0p1et size statistics for a water spray compared to several formulations delivered by perforated stainless steel and 70 um porous polyethylene sleeves. Wettable powder and flowable pesticide formulations are not represented for the polyethylene sleeve because the formulation components are not sufficiently fine to travel through the sleeve. Formulation clearly has an important influence on dr0p1et spectra. All formulations tested decreased the D50 of the spray spectrum as compared to that of water. This is probably due to a reduction in surface tension resulting from the formulation sur- factants. A 4-fold change in Diazinon 4EC concentration had little 97 .Nmeloe u swamp >ufivaass o>aumaou “commlmm I swoon ousumuOQEMu .mo:Hm> wouuoaou mo a: ma“ 6 .oommlmm coosuon voafiauouou mGOfimuwu oommusm v .a nm.a I unwaon “a Hm.c I mosmumaw opoun owuao .m\HE 5.0 I mum“ huo>HHov .m\u mmH I Auwooao> HmaOfiumuou AHV o>omam ”maOfiuflvsoo Hmucoacoufi>cm o .m\a n.mm I hufiooao> yam umauumo "mumumEmumm wcaumumoo n .zumasoo muosvoum oowmm m II III II II NmH NMN Hm nQ «.me H8 w.o + : HOHHIOUHQZ +. : I u-.. u- 3. m3 m3 2 3 m :3 He mmm .3 5.28 II III II II 05H CNN mm «Q H.0m HE w.o + : HOHHIOUHGZ + : II III II II an MCH #0 eq n.0m w DON m3 om aH>wm #0 NOH no me owH mNN eh me m.mm HE w.o + : HOHHIOUHNZ + : mm mm Ho cm Hm mm mm mm N.Nm H8 mm + : uum>fim + : Ho mm Ho em we m¢ Ho mq N.mm H8 50H : mm om mm am am NMH an co m.mm H8 «m : N9 0a on mm mm NMH on me N.¢m HE Nq ume COGHNMfiQ MNH QNH ¢m mm maH QQN mm Hm h.¢¢ HE m.o HOHHIOUHmZ mu MHH No on Hm mma #0 cc m.om H8 mm uum>fim hm wma om Hm NQH «ON mOH hm m.Nn IIIII Hmum3 oanlomn can Anz>vomn 0H9 oHanmn omn Anz>voma can vAao\mmamvv .H\ao«umuusoocoo Hmowaofiu o>oon ocoamnuohaom 8: oh o>ooam Hooum mmoHsHmum woumuomuom coamcoa oasflo> mmumm mo muwmusmuuom o>fiumasesu um Aasv muouoamao uoamoun oommusm o.n.m.mo>ooam umaaoumom Hooum muoHawmum woumuomuoa vow oaoamnuohaon a: on %n vouo>waov suuuomam uoaaouv manna as» so muouuoasahom Huofiamnu msoaum> mo uommmo 65H I .oH manna 98 effect on the droplet spectrum delivered by the 70 um porous poly- ethylene sleeve. Droplet size production from the perforated stainless steel sleeve using Diazinon 4EC, however, appeared to be more sensitive to formulation concentration (as judged by de- creases in D50). The effect of the two drift control agents was quite differ- ent. Nalco-trol had only a minor effect on the D50 values, but in- creased the D90 values substantially. This means that there is little effect on the small droplet portion of the spectrum, but that a few more large droplets are produced that shift the D90 values. This contradicts information supplied by the manufacturer claiming that Nalco-trol eliminates small droplets (less than 200 um), however, no data is presented for spinning sleeve type nozzles. Bivert had little effect on the droplet spectrum of the Dia- zinon 4EC formulation for either sleeve. Spectra of all sprays containing Bivert, however, were made up of droplets considerably smaller than the corresponding spectra of water. This is believed to be due to a reduction in surface tension accompanied with the addition of Bivert. According to information supplied by the manu- facturer, Bivert provides an oil coat surrounding the pesticide- water droplet thus inhibiting evaporation and consequently reduction in droplet size. Had Bivert been evaluated under increased sam- pling distances and environmental conditions more favorable for evaporation, the results with Bivert containing sprays may have been different. The spray droplet spectrum of a water soluble dye formulation 99 as effected by air velocity and sleeve rotational velocity is pre- sented in table 17. These data are discussed under "the effect of air velocity, sleeve spin speed and ratio of liquid proportioning to 2 Beecomist sleeves on the spray distribution delivered by a low volume spray system." The droplet size statistics for a non-aqueous spray medium (technical Malathion) delivered by several Beecomist sleeve types is presented in table 18. Again, it is clear that for the porous sleeve types, porosity and construction material has virtually no effect on the droplet spectrum produced. As with water, the per- forated stainless steel sleeve produced a droplet spectrum that is shifted more toward larger droplet sizes as compared to that produced by the porous sleeve types. The shift is more pronounced with the non-aqueous spray medium than with water. The greater variation in the D90 value is probably attributable to droplet fly- off problems from the tip of the probe, which appeared to be more severe with non-aqueous systems than with aqueous formulations. E. _ The Droplet Spectrum gfng Non-Aqueous Spray Medium §§_Deter- ‘mined With Both an_0ptic Probe and Droplet Impingement Harp. Table 19 presents droplet size statistics for dioctyl phthal— ate delivered by 70 um porous polyethylene and perforated stainless steel sleeves. For the perforated stainless steel sleeve, the droplet impinge- ment harp did not capture as large of droplets (at either distance) as detected by the optic probe. 100 Table 17. - The effect of carrier air velocity and sleeve rotational velocity on the spray droplet spectrum of a water soluble dye formulation delivered by a Beecomist perforated stainless steel sleeve.a’b:c’d Air Sleeve Droplet Diametere (um) at Cumulative Velocity Velocity Percentages of Spray7Volume (”’3’ (P’s) D10 Dso‘VMD) D9o D90"”10 22.4 100 98 192 265 167 " 183 46 104 184 138 33.5 100 94 193 259 165 " 183 51 102 193 142 44.7 100 110 201 271 161 " 183 56 111 191 135 Beeco Products Company. Dye formulation 8 Uranine (Sodium Fluorescein) 132 g/l + Orthene 755 26 g/l. Operating parameters: delivery rate (1 sleeve) = 6.7 ml/s. optic probe distance = 0.91 m; height = 1.37 m. Environmental conditions: temperature = 24°C; relative humidity = 61%. 115 um of reported values. 101 Table 18. - The spray droplet spectrum of technical malathion delivered by several Beecomist sleeve types.agb,c:d Droplet Diametere (um) at Cumulative Percentages of Spray Volume Sleeve Type D10 D50(VMD) ‘ D90 D90'D10 20 um stainless steel 35 69 112 77 60 um stainless steel 35 72 126 91 70 um polyethylene 34 73 131 97 perforated 74 151 248 174 stainless steel Beeco Products Company. Operating parameters: carrier air velocity = 33.5 m/s. sleeve (1) rotational velocity = 183 r/s. delivery rate = 15.8 ml/s. optic probe distance = 0.91 m; height = 1.37 m. c Environmental conditions: temperature range 8 22-25°C. relative humidity range = 58-63%. d Surface tension of technical malathion = 33.6 dynes/cm at 24°C. e :15 um of reported values. 102 .mmsam> wmuuonou NO as mHH .ooqm um Eo\mm:%v m.oq u oumamsuca ahuooww mo seawcmu momMHSm v .Nmolwm mwcmu wufiwfiazs o>wumamu "OomNINN I owsmu manumuoaamu "maoaufivcoo Houaweaoua>um o .B mm.a I unwwoz mswanamm and: was onoum ofiuao .m\aa n.o I sump auo>fiamw .m\u mmH I mufiuoao> Hmcoaumuou AHV o>moam .m\fi m.mm n xuwooam> was uofiuumo ”muwumEmqu msfiumumoo n .xsmaaoo muuswoum oumom m omfi amm qu mc mu moH ONH em on mmH Hm om mo.m : : Nod onm «ea so oq mm mm am Re mm mm mm Hm.o Hmoum mmoasfimum vmumuomuma mm «Ha an mm mm mma mm mo mm oNH mm as mo.m : : cw mas Hm mm mm mm me an we we om mm Hm.o mamaasumafioa a: On oanlcmn com one can OHQIO¢Q can 0mm can oHQIoma can 0mm oH Aav ommfi o>ooam monoum ofiumo Hmoum mmoaaamum a: ma mama usoamwsaaaH uoanoun so mnam ouwz coumwsse a: m mESHo> mmuam mo muwwuaooumm o>fiumaseao um Aasv umuoamwn uwflmoua m>mon umBoq scum mosmumfin mafiamamm w.o.n.m.aum£ uamsowswnaw uoHaouv m was «noun oauno cm saws voswahouow mm mo>omam umanooom Hooum mmoaufimum vmumuomuoa was mamaanuohaon B: On an wouo>waov oumamnunm ahuoowv mo asuuomnm uoanouv human one I .ma manna 103 In comparing the harp with the probe for the 70 um polyethyl- ene sleeve, the D10 and D50 values were more comparable at 0.91 m that at 3.05 m, whereas the D90 values were more equivalent at 3.05 m. The fact that the harp does not catch the same size drop- lets at each distance is indicated by a shift in the whole spectrum (D10, D50, D90 values). The droplet impingement harp was more efficient in collecting larger droplets as sampling distance and/ or wire size was increased. The shift in the spectrum as a func- tion of wire size is partly due to an increase in catch efficiency but also due to the inability in measuring as many small droplet size classes with the 15 um wire as compared to the 5 um (6 versus 9 under 50 um). Virtually identical droplet spectra were obtained at both dis- tances with the optic probe. One cannot eliminate the possibility that droplet fly-off problems from the probe, however, may have contributed to the droplet spectrum obtained. The selection of a wire size for use on a droplet impingement harp must involve consideration of the droplet size being delivered and its traveling velocity at the point of collection. 104 REFERENCES CITED Anderson, C. 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