Using LOW-VOLUME FARM SPRAYERS CIRCULAR 126 / JANUARY 1959 45lgricii/tura/ 6 ,e xperimnent Station of tte ALABAMA POLYTECHNIC INSTITUTE E. V. Smith, Director Auburn, Alabama CONTENTS Page BASIC PARTS OF A SPRAYER ----------CA LIBR ATION ------------------------------------4 8 11 -13 ADJUSTMENTS TO OBTAIN DESIRED APPLICATION RATEMIXING THE SPRAY SOLUTION -------SELECTION AND ADJUSTMENT OF EQUIPMENT FOR DIFFERENT SPRAYING JOBS ------------- Pre-emergence Weed Control Post-emergence Weed Control----Insect Control --------------- --- --------- -- --Defoliation ---- -- - --- - --- - -- - --- - --- -- - --- Pasture W eed Control --------------- --Wheel Fenders-20 -- -15 16 -18 - 19 -15 -20 High-Clearance Sprayers ------------------------------ 21 Miscellaneous Spraying ------------------------------ 21 OPERATION AND CARE OF SPRAYERS ---------- _-----------.21 Beginning of Season Care Field O peration ---------------------------- 21 22 .------------------------------------- Daily Care -- - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- 2 2 End of Season Care -------------------------------- 23 MISCELLANEOUS -----Tank Measuring or ------ ------------------------- 23 Cauge Stick ---------------------- 23 Filling Tank with Spray Pump .----------------------. 23 Caution About Using 2,4-D and 2,4,5-T----------------24 FIRST PRINTING 5M, JANUARY 1959 Using Low-Volume Farm Sprayers T. E. CORLEY, Associate Agricultural Engineer* WORLD WAR II there has been increasing interest in farm use of liquid chemicals. This interest has centered around development of chemical weed killers, liquid insecticides, liquid fertilizers, and liquid defoliants and desiccants. Since high gallonage application of the chemicals in dilute form was sometimes ineffective and impractical, low-volume sprayers were needed. Engineers working with entomologists developed low gallonage, low-pressure sprayers that give effective control of insects with applications as low as 1 gallon of spray per acre. In this publication, a sprayer that delivers 1 to 30 gallons of spray per acre at a pressure of 10 to 100 pounds per square inch (p.s.i.) is considered a low-volume sprayer. New chemicals and sprayers have been developed at a much faster rate than have their use on farms. Several factors have contributed to the rather slow acceptance of sprayers in Alabama. These include difficulties in mixing spray solutions, in determining the volume of spray applied, and in using, adjusting, and caring for the equipment. The purpose of this publication is to explain proper sprayer use, how to calibrate the sprayer, how to mix chemicals, and special uses of spray equipment. The information presented is based mainly upon 10 years experience with sprayers in cotton mechanization research by the Agricultural Experiment Station of the Alabama Polytechnic Institute. In these studies, sprayers were used for chemical weed control, insect control, and defoliation. SINCE * Cooperative Agricultural Experiment Station of the Alabama Polytechnic Institute and Agricultural Engineering Research Division, ARS, USDA. To oz To nozzles _ Suction Hose Pump FIGURE 1. Basic parts of a sprayer are shown in this schematic diagram. Basically, a sprayer is simple in construction and operation. Figure 1 is a schematic diagram of a sprayer. A typical tractor sprayer requires a pump mounted on the tractor power take-off (PTO) with a suction line connecting the pump to a tank mounted on the tractor. As the tractor PTO is rotated, the pump sucks the spray liquid from the tank and puts it under pressure. The liquid leaves the pump under pressure and goes through a hose to a by-pass regulator where the pressure of the liquid going to the nozzle is regulated and excess liquid is returned to the tank. The spray is applied through various types of nozzles, depending upon the job to be done. BASIC PARTS of A SPRAYER Pumps. Pumps for low-volume sprayers should deliver at least 5 gallons per minute at pressures up to 100 pounds per square inch when rotated at 550 revolutions per minute. There are many types of pumps and several makes and models of each type. Selection of a pump depends on the material to be used, cost, and pressure and volume of spray to be applied. This Station has not conducted comparative tests of pumps, but it has purchased and used gear, roller, diaphragm, and piston pumps, and the following observations were made: [4] Gear and( roller pumps have short life spans xxhlen used for puminug suspenisions of xxettable powder or dlirty, gritty wvater. Hlowexver, these pumps1~ haxve giv en satisfactorv serv ice for :3 or 4 sprax irng seasons wvhen usedl for pumping emulsions and solutions. Diaphragmu and p~iston pump~ xxill handle wettab~le p~owxder solu1 s tions in addition to emululsions and solutions. These pum~ps reMurea chamber in the line to give a steadyx flow of liquid air to the niozzles. Strainers. All spray ers should he equipped with strainers or screens to prexvent Clogging of the nozzles, Figure 2. A strainer should he located either on the end of the suction hose or in the line lhetxxeeu tausk and pump and each nuozzle should he equipped FIGURE 2. Strainers are necessary to prevent clogging of nozzles. strainer (left )is contrasted with clean nozzle strainer at right. A clogged xxithi a stinr. Line and suction straiuuei s should haxve 50 to 100 mnesh screens and the nozzle should haxve screens of 50 to 200 mesh, depending upon size of nozzle orifice. The screen mesh must he selected to let all foreign particles [pass that xxill not clog the nozzle. Hose. [ron the standpoint of p~resstire, garden hose is satisfactory for a loxvxolume spray er. Garden hose is also satisfactorx for muost spra\ solutions lbut Ncophreiie hose should he used for handling spray solutions Containing oil. [51 Pressure regulator and gauge. The low-volume sprayer uses a positive displacement type pump. Since it pumps more than the nozzle is applying, a by-pass pressure regulator must be used to return the excess liquid to the tank and to obtain the desired nozzle pressure. When the nozzles are not spraying, all liquid from the pump is returned through the by-pass. The excess liquid returned through the by-pass serves to keep the spray solution in the tank agitated. The nozzle pressure is easily and quickly changed by a simple screw adjustment of the pressure regulator. A gauge should be mounted near the regulator and in easy vision of the tractor driver. The gauge should have a pressure range of 0 to 100 p.s.i. Nozzles. According to the type of spray patterns produced, nozzles are classified as flat or fan, hollow cone, and solid cone. Each type is further classified according to capacity, and fan type nozzles are also classified according to angle of the spray pattern. These classifications apply to the nozzle tip because this part of the nozzle determines the type and volume of spray. The tips are interchangeable and are easily removed and replaced. Most fan type tips are marked to indicate the angle of spray pattern and the capacity in gallons per minute at 40 p.s.i. Cone type tips are usually marked to indicate gallons per hour at 40 p.s.i. Manufacturers don't use the same markings but they all have charts showing the capacity of each tip. Types of tips needed for specific jobs are discussed on pages 15-20. Tanks. Clean 55-gallon steel drums can be used for most spraying jobs. Although low in cost, these drums rust and corrode and have to be replaced after 1 or 2 years use. Stainless steel and aluminum tanks are more costly than steel drums, but they resist the corrosive action of most chemicals and result in less nozzle clogging and give many years of service. Booms. Booms may be up to 30 feet in length, depending upon smoothness of the ground and acreage to be sprayed. Booms longer than 10 or 12 feet need flexible end sections that permit raising for gate and highway clearance and to facilitate turning in close places. Provisions for raising the end sections from the tractor seat are desirable but not necessary. Boom height should be adjustable. Good coverage is usually obtained with the nozzles about 20 inches above the plants. For row crop spraying, outlets should be spaced on the boom to permit mounting one [6] nozzle ov er the row' aicd a nozzle wvith all extension (drop pipe) between the rowxs. For 40-inch rowxs, the nozzle outlets should Ihe spaed~ 20 inches apart on the boom. This same spacin g is also satisfactory for b~roadcast sp~ray ing. Galv anized pipe may be ed for the boom and drop extension s. Mounting frame. A frame is nlecessar\ for supporting the tank andl boom. It should lbe strong enough to hold the tank and hooinS rigidLl\ wxithout swxax ing. A full .55-gallon dIrtm weighs albout 500) poundi~s andl it sholld Le munted so as not to affect stab ility of the tractor. The fram e should be simplle to mi)Innt and dLetach. [or row~ crop sprax ing, the frame should hav e amp11le clearanee wxithotit aiiy low braces. Figure :3 shows a rear-ntotiiited tanik andl 1)0011 support used for pre- and( post-emergeilee weed con trol, cotton insect con trol, and1( defol iationI and1( a oluiiek-hiitch FIGURE 3 (tap). At left is a rearmounted tank and boom support with ample clearance to permit use of rear cultivator during pre- and pest-emergence operations. Tractor wheel was removed to show axle mounting of t support. A quick-hitch tank support with bracket for mounting a broadcast nozzle is at right. L p I FIGURE 4 (right). This front-mounted' tank support is used for pre-emergence chemical application with planters mounted on rear.__________ tank support with mounting bracket for broadcast nozzle. A front-mounted tank support used for pre-emergence weed control with rear mounted planters is shown in Figure 4. Frames may be purchased or "homemade" like those shown. Large tanks (100 to 200 gallons) should be mounted on trailers. Several interconnected 55-gallon steel drums can be mounted on one trailer. CALIBRATION It is important to know how much spray the sprayer is applying. Proper amounts of chemicals that should be applied for best results have been determined and the sprayer should be adjusted and operated to apply these recommended rates. Too much spray may cause injury and is a costly waste, and too little spray will not do the job. Calibrating or determining the amount of solution the sprayer is applying can be done by collecting and measuring the solution from a nozzle while operating the sprayer over a measured distance under conditions similar to those that will prevail when actually spraying. The volume of spray applied per acre can then be calculated. To avoid complicated calculations, Figures 5 and 6 can be used to determine rate of spray. Figure 5. As shown in the instructions on Figure 5, its use is based on catching spray from a nozzle until a pint jar is full. If two people are available, one will drive the tractor and the other will walk and hold the jar under a nozzle. When the nozzle is mounted close to the ground as necessary for pre- and postemergence weed control, the nozzle can be detached from the mounting bracket so the jar may be conveniently held under it. To calibrate with one person or to eliminate the necessity of detaching a low-mounted nozzle, the following procedure can be used: With tractor stationary but running with throttle set at operating speed, run sprayer and determine time in seconds required to catch a pint of spray from a nozzle. Then put tractor in field and determine how far it travels in that length of time. Then read chart according to instructions. Example: If the tractor traveled 273 feet in the time required to collect a pint of spray, the chart shows you are applying 6 gallons per acre on 40-inch rows. [8] la 174 16 15H 14 13 12 Il S10 u, 36-in. rows 4, 38-in. row - I7 6 40-in, ro ws 42-in. rows Fee S trvled t Example: 1 pint If you ach Ipn taeld18 sprayadhv ett -6rows, Scatch ar e gve the chart h rowsw: of 0ic 2. t- racorinfild -Pu -t n .pe Exaps 3. ihwacan paerad t i y t e 1 e htt pin t opratanghaveed0-inch 1 resur bewe10and0 4. ratorin ut peatFe 20p20u00d50 earavelledtoteceatch 40 oIpein ped FIGUrk5strtipontfordusgthetaoveharot 2toalbaeirow-croipopryer aregivent a ndbelow:e oucosstrigpon n cniu i il 1. MUsute nt a ta6nces)avllto atchlspayromanoze 2. PuRacatraicfiedin opteat ing it. o ons 3. Withewaerosinotmspryradtottlestatoeraletctingspedpdjut.pesr 4. Putetrac to opratnv e rwwith.trtl e toeaigsed aof 5. Mrkesarngpoinetcadsaartmngeaaos20peetacbe.histtinupint 6.rPutgapinsjaplundper ozze whencosslestaro.Itndyontineinofeldha u enti orisfll.e omlil heglosb h u br fnzlsprrwt 8.g ead alspraccrdigth.floigintutos a.o MoveI mst tomve scae t t ros anc40 fe trvl to catch 1 pint.ea al-pn b.r Movun e)upndthoueof row wih. n-hl ftatsono tecat c.Mvearostovrtclscl adredgalnsprace1Ti9i1henm 35 30 15 A 'similar to that in field. 5 a I u . o s refill tank and you are using a 30- I I_ I/ 5 Move bottom across tox -a. scale gallons used to refill tank.to refill tank and you are using a 30n !l ., r ! b. Move up the line of your swath widthe chart shows you to c. Move to the verticarl scale applying 17 gallons per acre. left Gallons used to refill tank after spraying 300 feet 2. With water in sprayer and throttle set at operating speed, operate sprayer and adjust pressure to the desired setting (10 to 60 pounds). sprayer over the 300-footdistance. c. Move left to the vertical scale and read gallons per acre. [10] If you know how many gallons per acre that you want to apply, use chart as follows: Move up the scale to gallons per acre desired, then across to the curve of your row width, and down to get the distance to travel to catch a pint. Mark this distance off in the field to be sprayed. Now with throttle set at operating speed, determine how long it takes to travel this distance. Then with tractor stationary but with throttle set at operating speed, change pressure and/or nozzle size until a pint is caught in the time required to travel the measured distance. If you change the throttle setting, you must again determine how long it takes to travel the required distance. Example: If you want to apply 10 gallons per acre on 40-inch rows, the chart shows that you must travel 165 feet to catch a pint. If it required 35 seconds to travel this distance, adjust pressure and/or nozzle size until a pint is collected in 35 seconds. Now your sprayer is adjusted to apply 10 gallons per acre. Figure 5 was prepared primarily for row crop sprayers, but it can be used for a broadcast boom sprayer. Example: A broadcast sprayer with nozzles spaced 20 inches on the boom would be the same as a 40-inch row crop sprayer with 2 nozzles per row. Figure 6. Figure 6 can be used for calibrating any type of sprayer, but it was designed especially for a broadcast type. Since it is rather difficult to catch spray from a broadcast type nozzle, the amount of spray applied is determined by measuring the volume sprayed from the tank. As described in the instructions on Figure 6, this is done by starting with a full tank, spraying a measured distance, and measuring the amount needed to refill the tank. The tractor should be on level ground when the tank is filled and refilled, preferably in the exact location. ADJUSTMENTS to OBTAIN DESIRED APPLICATION RATE Figures 5 and 6 are used to determine how much liquid the sprayer is applying. If the desired amount of solution is not being applied, changes must be made and the sprayer must be calibrated again. The amount of liquid a sprayer applies per acre is governed by the speed of the sprayer, size of nozzle orifice, pressure, type of solution, and the nozzle spacing or number of nozzles per row. Pressure. The best way to make small changes in volume of spray is to change the pressure. For most insect and weed spray[11] ing jobs, the pressure may range between 20 and 100 pounds. The lower pressures (20 to 50 p.s.i.) are usually desirable because with lower pressure, a large orifice will give the same discharge as a small orifice at high pressure. The larger orifice will give less trouble in clogging and produces larger droplets that reduce wind drift. Example: A fan type nozzle with a rating of 0.1 gallon per minute requires a 100-mesh screen and will apply 10.4 gallons per acre when operated at 80 pounds pressure at 2 miles per hour. A nozzle with a rating of 0.2 gallon per minute requires a 50-mesh screen and will apply the same volume (10.4 gallons per acre) when operated at 20 pounds pressure and at 2 miles per hour. With the same orifice, the volume per acre can be changed by changing the pressure. To double the volume of a nozzle, the pressure must be increased 4 times. The change in volume in relation to pressure for a fan type nozzle with a rating of 0.2 gallon per minute when operated at 3 miles per hour and with 1 nozzle per row is as follows: 20 p.s.i. 30 " 6.9 gallons per acre p.P p 8.4 40 50 60 80 " " " " 9 .9 11.4 12.4 13.8 . . . p p pp. pp p .p 100 15.8 The change in pressure also affects the spray angle. For band spraying, this change may be compensated for by raising or lowering the nozzle. For boom spraying, the overlap will take care of slight pattern changes. With a broadcast type nozzle, the swath width may be affected 10 or 15 feet by pressure changes. When calibrating a sprayer, start with a pressure of about 30 pounds and increase or decrease to make minor changes in volume. Nozzle orifice. The best way to make a large volume change is to vary the size of nozzle orifice or opening by changing nozzle tips. The amount of spray a nozzle delivers is in direct proportion to the square of the diameter of the orifice opening. In other words, if the diameter of the orifice is doubled the volume is increased 4 times. Most nozzle orifices are not designated or rated by diameter but by capacities in gallons per minute or gallons per hour at [12] a certain pressure. In selecting a nozzle size, refer to tables that give volume per acre at different speeds. Example: The capacity of 1 nozzle per 40-inch row operating at a pressure of 40 pounds varies with nozzle size and speed as follows: Nozzle rating Gallons/min. 0.05 0.1 0.2 0.3 0.4 Gallons/hr. 3 6 12 18 24 3 2.5 5.0 10.0 15.0 20.0 Speed (m.p.h.) 4 5 Gallons per acre 1.8 1.5 3.7 3.0 7.4 6.0 11.1 9.0 14.8 12.0 6 1.2 2.5 5.0 7.5 10.0 If it is desired to apply 10 gallons per acre with 1 nozzle per 40-inch row, select a 0.2 nozzle tip if traveling 3 m.p.h. but a 0.3 tip if traveling 4 m.p.h. After selecting the nozzle tip, it may be necessary to make slight pressure changes to get exactly 10 gallons per acre. Speed of sprayer. The speed of the tractor or sprayer should be the last variable to change. When applying pre- and postemergence weed control chemicals, the speed should be governed by the planting and cultivating speed. In pasture spraying and cotton poisoning and defoliating, speed is governed by terrain, safety, and damage to crop. Volume is indirectly related to speed. When the speed is doubled, the volume is reduced by one half. Nozzle spacing or nozzles per row. The amount of spray is directly related to the number of nozzles per row. Type of liquid. When a chemical is diluted with water, the sprayer can be calibrated with plain water. If the chemical is an oil or is diluted with oil, the same oil must be used for calibration. MIXING the SPRAY SOLUTION After the sprayer has been calibrated to determine its rate of spraying, the concentrate chemical must be mixed in correct proportion with water. The strength of most spray chemicals is marked on the container and is usually expressed in per cent of active ingredients and/or pounds of technical material per gallon. Many chemicals are sold at different concentrations and it is important to read the container label before mixing and using. Example: Toxaphene may be purchased with 4, 6, or 8 pounds [13] of technical material per gallon. Most recommendations are expressed in terms of pounds of technical material per acre. It is relatively simple to mix the spray solution if the following three things are known: (1) amount of solution the sprayer is applying per acre, (2) pounds of technical material per gallon of concentrate chemical to be used, and (3) pounds of technical material recommended per acre. Example: Assume that (1) your sprayer is applying 5 gallons per acre, (2) you are using toxaphene containing 4 pounds of technical material per gallon, and (3) you wish to apply 2 pounds of technical toxaphene per acre. Each gallon of the toxaphene contains enough technical material for 4 pounds per gallonacres acres = 2 acres Or gallon of this 2 are 2 pounds per acre toxaphene contains enough technical material for 1 acre. Therefore, for each acre you should mix 1/ gallon of concentrate toxaphene with 41/2 gallons of water. Or for each gallon you should mix 9 gallons of water. To mix a 55-gallon drum of spray (enough for 11 acres), fill drum about half full with water, put in 51/2 gallons of concentrate toxaphene (enough for 11 acres) and then fill drum with water. Always have water in the tank when adding concentrate chemicals. After pouring the water and chemical in the tank, operate the pump for several minutes with the nozzles turned off to thoroughly mix the spray solution. All chemicals are not marked in terms of technical material per gallon. However, the label or the recommendations will tell how much of the concentrate chemical to apply per acre. The strength of wettable powders is expressed in percentage of active ingredients, and the recommendations are usually in terms of pounds of powder per acre. Make sure that the powders are thoroughly mixed with water before pouring into the tank. 1/ CAUTION. Before mixing any chemical, read and understand the precautions and directions for safe handling. This information is on the container label. The mixing process involves handling highly concentrated chemicals and even non-toxic chemicals in concentrate form can cause severe burning, blistering, and other harmful effects. Avoid as much as possible contact of the chemical with skin and clothing. If the chemical gets on the skin, wash thoroughly with soap and water immediately. If it gets on clothing, remove clothing at once. Always have soap and water readily available. Make sure that measuring and mixing containers are thoroughly washed before using for other purposes. [14] SELECTION and ADJUSTMENT of EQUIPMENT for DIFFERENT SPRAYING JOBS The h~asic elements of a spraver (pump, strainers, hoses, and tauk) may he used for many jobs. Nozzle tvpes, sizes, arrangeients, andl methods of mounting varv with the joh. Pre-emergence Weed Control Pre-emergence chemicals are applied after planting and before the crop and weeds emerge or come up. Cotton, peanuts, andl corn are the main crops in Alahama that lend themselv es to preemergence treatment. Although chemicals can be applied broadcast oxver the entire field, it is more economical to treat onlx the row (hand application) anld use sweeps to control weeds between rowxs. For hand application, the chemical should he applied in connection with the planting operation. Application of the chemical after crop is planted means an extra operation, makes it difficult to center hand over the planted row, and introduces a chance of rain preventilg treatment hefore the crop emerges. To apply pre-emengence chemical at planting, mount the spraxver on the tractor with a nozzle over each row. The fan type nozzle with an ex en, flat spray pattern was designed for hand Ps .. _~ -S 6 ~'^-a- ::~ t a~-iT -~" L FIGURE 7. Distribution pattern of an even, flat spray nozzle at right is compared with a regular, flat nozzle with a tapered edge pattern at left. [15 1 application of pre-emergence chemical, Figure 7. However, the regular fan nozzle with tapered edge pattern may be used. Use 6.5- to 110-degree fan ty pe nozzles with a capacity of 0.2 to 0.4 gallons per minute . Nozzle pressure may xvary from 20 to .50 p.s.i. The table on page 13 will serve as a guide for selecting the correct size nozzle for your operating speed. The volume of spray may v ary from 7 to 14 gallons per acre. Some states recommendl a gallon of spray per acre for each inch of band wx idth. The iozzle should be mounted b~ehind the planmter press wheel in such a manner that it xill remain a constant height abov e the row. To (10 this, the bracket supporting the nozzle is attachedl to the mounting frame of the planter press wheel. The nozzle should b;e mounted to permmit vertical adjllstlent so that the desired hand width can be ohtained by raising or lowering tgthe nozzle. A band width of about 12 inches has prove satisfactorx. A regular press xxheel can he used but the xxide, solid press wx heel, Figuire 8, leav es a desirable surface oi xhich to apply post-emergence chemicals. FIGURE 8. This 12-inch solid press wheel leaves a desirable surface far applying pre- and past-emergence chemicals. The two small disks mounted behind the press wheel are not necessary but they eliminate ridges on each side of row and provide small furrows for row drainage. Post-emergence Weed Control Poost-emergence chemicals are applied after the crop and weeds emerge. Post-emergen ce sprays are recommenided for cotton, corn, sorghum, and small grains. Post-emergence application is easy for corn, sorghum, and small grains because these crops will [16] tolerate light dloses of the weed-killing cheicals. Although corn and( sorghum wXill tolerate th~e weed-killing chemicals, the ntozzles should he set to direct spray toward base of the stalk to prev ent chemical from hitting the corn or sorghum leaves. In small corn, the nozzles can he attached to the cultix ator. For large corn, an oxverhead hoom with) drops ini each middle is needled. Post-emergence weed control in cotton is more dlifflecult because the wxeed- killing chemicals cannot hit the yo0u1ng Cotton leax es wXithout damaging or killing the cotton. Ilowex er, the chemiicals max strike the shank of the v oting cotton stalk before the true hark forms without damaging it. This makes it possib~le to spray small grass and wxeedis ini the drill wxithiout dlamaging the to :3inches tall at (jottonl. C;ottont plants should be at least 21. time of first application. The chemical should be applied wxithouit dlistmirbing the soil in the (Irill. At the same time, the midd~les caun be cultivated wXith sweelps. The chemical can be app~lied when . the groundl is too wXet for swe ep cuiltiv ation but wvill sulpport the tractor. Figure 9 shoxvs shields used to keep the swxeeps fromt throwxinig dlirt in to the rowv crill . Nozzles moulntedl on the shieilds are di- FIGURE 9. Shown are parallel action shields with nozzles (arrows) mounted for applying post-emergence chemicals. These shields prevent sweeps throwing dirt on the row when cultivating and applying post-emergence chemicals. [I17] rected to spray weeds in the drill. The flat plate on the boottom of the shield and the parallel linkage cause the shields to float on the ground surface, thereby keeping the nozzles at the sae height. The nozzles should lbe mountl on each side of the row about 1 inch above the grolnd surface and directed so that the sprax hits only the bottom inch of the cotton stalk. The nozzles may be directed to the rear at an angle of ahouit 30 to 40 degrees with the rox or pointed straight across the row. In either case, the nozzles should be set to cover an 8- to 10-inch band on the row. If the nozzles are poinrted straight into the row, make sure that thex are offset (not set opposite each other) so that the sprav s will iot meet an(d "bounce" up1 and onto the cotton. For post-emergence spraying, use 65- to 95-degree fan tx pe nozzles xith a capacitx of 0.05 to 0.1 gallon per minute. ()perating pressure ma xvarx between 1.5 and 40 p.s.i. Insect Control Spraxers cain be used effectively to apply ilsecticides on most crops. Nozzle arrangement varies with the cjop and insect. For cotton insects, the nozzles should be arranged to gixve good coverage of the terminal growth. Fiiure 10 shows anl eight- ~ A--- FIGURE 10. This 8-row sprayer is equipped with 3 nozzles per raw for applying cotton insecticides. The inset shows how home-mode shields are mounted on tractor to reduce mechanical damage to cotton during insecticide application. [18I8 row sprayer for applying insecticides to cotton. This sprayer is equipped with 3 nozzles per row (1 centered over the row and 1 on each side). This nozzle arrangement has given good control in test work in Alabama. For small cotton, 1 or 2 nozzles per row will give good coverage. Cone nozzles with a capacity of 4 to 6 gallons per hour or fan nozzles of equal capacity (0.067 to 0.1 gallon per minute) are recommended for applying most cotton insecticides. Nozzles with smaller orifices will give adequate coverage but cause more trouble in clogging. Nozzles with larger orifices can also be used and may be needed during windy weather and for high rates of application. The table on page 13 may be used as a guide for selecting nozzle size. Good coverage can be obtained with 5 to 10 gallons of spray solution per acre. For the corn earworm (on sweet corn), direct the spray into the ear zone. Because of non-uniform ear height, 2 nozzles on each side of the row should be used. For the corn borer, use 1 nozzle above the row and 1 on each side, directed to get the spray into the whorls. Defoliation Cotton is the main crop that is chemically defoliated in Alabama. Defoliants can be applied with the same equipment used for applying insecticides. Larger volumes of spray are needed for defoliation than for insect control because each leaf must receive an application of the chemical. Defoliants should be applied in 15 to 25 gallons of water per acre. A coarse spray with large droplets is desirable. The larger nozzles recommended for insect control can be used for applying defoliants. An overhead boom with drop extensions in each middle and 3 to 6 nozzles per row will give good coverage in cotton under 5 feet in height. For larger cotton, a second application is usually needed. The broadcast type nozzle, Figure 11, has given excellent defoliation in tall irrigated cotton for 2 years at Auburn. Good was obtained on all rows of an 8-row swath, but with wider swaths outside rows did not always get ample coverage. Flooding type nozzles mounted overhead have given excellent results in defoliating rank cotton in other states. Sometimes it may be desirable to defoliate the lower part of cotton plants without disturbing the top. This can be done by using an overhead boom with a drop extension in each middle. Mount nozzles only on the drop extensions and direct them to coverage [19] BROADCAST SPRAY NOZZLE FIGURE 11. Shown above is one type of broadcast nozzle. swaths up to 60 feet. This nozzle covers coy er tbe lower portion of the plant. A shield (6 to 8 inches wide) miounted oni the drop) extension will keep leax es from lhriishiiig aicross the nozzle orifice. Pasture Weed Control The greatest use of lowx-v ohlme sprav ers in Alabama has been for sprax ing wxeedls in pa~stuires. Broadcast type spray ers are nsed for p~astuire spray ing and arc of two ty pes: (1) boom 'tx pc sprax ers with fan nozzles spaced 18 to 2() inches on the boom, and (2) biroadcast nozzle ty pe spray ers with a cluster of nozzles arranged to cox er a wide swath. The b~roadlcast tx pe nozzle has become xvcry popuilar for pastuire weed control. Spray ing xxith a b~roadcast nozzle as compared to spray ing wxith at b)oom type sprayecr has the followxing adx amtages: (1) lowxer equnipnment cost, (2) fewxer noz)! zlcs to maintain and to causecloggn~. (>) easier to operate, and (4) pemt spaing wider swxaths. Disadv antages of spra inig with a hroadcast nozzle are: (1) wxin d unatcriallx affects the nozzle pattern, (2) difficuilt to maintain uniiform distan ce 1 etwe ccn wxide swxaths, and (3) greater danger of spray ing nearlby cro ps. With either ty pe spray er, good cov erage may lbe obtainecd wxith I ( to 25 gallon s per acre. For large acreage, trailer ty pe spray ers equlipped with large tanks arc desirable. Wheel Fenders M echoan ical damage to crop)s caused byxground applicators of insecticidles max he quite serious, especciallx during late seasoni in tall crops. Whleel fenders such as those shown in Figure 10( aid greatly in reducing this damage.. These are . shop-mnade" fenders [ 20 1 constructed from a 30-gallon insecticide drum and mounted to the sprayer frame. They can be mounted independent of the sprayer frame by clamping to the tractor axle. They are mounted in a fixed position and a piece of 10-inch belting is fastened to the bottom of the drum. This belting will push the low limbs out of the way of the tractor wheel but will give or flex when the wheel drops in a ditch or crosses a terrace channel. Wheel fenders such as these may be constructed and adapted to any make tractor. Similar wheel fenders are available commercially. High-Clearance Sprayers Self-propelled, high-clearance sprayers are relatively costly, but they are desirable for use on large farms and by custom operators. The use of self-propelled, high-clearance sprayers reduces mechanical damage to growing crops and eliminates need of a farm tractor for spraying. High-clearance sprayers are especially adapted for application of chemicals in tall crops, such as corn and irrigated cotton. They may also be used to apply liquid fertilizer, chemicals for weed control in pasture or row crops, cotton defoliants, and for other spraying jobs. Miscellaneous Spraying The low-volume farm sprayer can be used for spraying livestock, buildings, manure piles, orchards, ditchbanks, fence rows, and shrubs, for washing and cleaning farm equipment, for fighting fires, and numerous other jobs. A hand gun and a 25-foot hose are the only extra equipment needed to adapt a row crop or pasture sprayer for the above miscellaneous spray jobs. OPERATION and CARE of SPRAYERS Beginning of Season Care 1. The sprayer mounting frame should be fastened securely and braced properly to the tractor. 2. All pipe and hose connections should be leakproof. 3. Make sure that pump can be turned by hand before mounting it on the tractor PTO. (Note: If pump cannot be turned by hand, it should be disassembled according to instructions furnished with pump.) [21] 4. Do not pound or hammer the pump to get it on the tractor PTO. If the PTO shaft and the pump coupling are clean and free of rust, the pump should go on easily. 5. Secure pump to PTO by means of set screws and anchor pump to sprayer or tractor with chain or chains. 6. Inspect tank and make sure it is clean before mounting. 7. Flush boom with water before attaching the nozzles. 8. Inspect nozzle screens and tips for cleanliness and to make certain all tips are of the same size. 9. Run sprayer to check for leaks and to observe nozzle patterns. Irregular shaped nozzle patterns may be detected by observation and must be corrected. They are usually caused by trash or dirt in and around the nozzle orifice or by a clogged nozzle screen. Do not probe the nozzle orifice with a knife blade or other metal objects. Use a tooth brush or soft wood to clean the orifice. 10. Calibrate sprayer and mark throttle setting and record gear position. 11. Calculate the ratio of concentrate chemical and water and record mixing instructions on tank or other convenient place. Field Operation 1. It is of utmost importance to always use a clean spray solution. 2. Operate tractor in the same gear and at the same throttle setting as used for calibration. 3. Observe nozzle patterns continuously to detect clogged nozzles and to tell when tank is empty. 4. Do not operate pump when tank is empty. Gear and roller pumps can be seriously damaged by operating dry only a few minutes. Daily Care 1. At the end of a day's spraying, flush system with clean water. 2. Check suction and line strainers and nozzle tips and screens and clean if necessary. Clean tips and screens by soaking in gasoline and brushing with a small brush or use compressed air. [22] End of Season Care 1. Flush system thoroughly with clean water and then run a few gallons of fuel oil through sprayer to help prevent rust. 2. Remove and clean nozzles. 3. Remove and drain pump. Before storing, gear and piston pumps should be filled with oil and roller and diaphragm pumps should be flushed with a rust inhibitor. All openings in the pumps should be plugged. 4. Apply a coating of oil to the inside surface of steel tanks. 5. Store sprayer under a shed. MISCELLANEOUS Tank Measuring or Gauge Stick It's a simple matter to mark a stick to use for measuring the amount of liquid in your sprayer tank. With the tank level, add 5 gallons of liquid, insert stick in tank, and then mark or notch stick. Continue to add 5 gallons at a time and mark stick until tank is full. Always make sure the tank is level when using the gauge stick. The following figures have been obtained for measuring the amount of liquid in a 55-gallon steel drum in a horizontal position: Inches per 5 gallons Gallons 5 10 15 20 25 30 35 40 45 50 Inches 31/8 51/ 67/8 81/ 10 111/2 131/8 143/4 16% 181/8 Inches 1 2 3 4 5 6 7 8 9 10 Gallons per inch Gallons 11/4 3 43/ 7 93/ 12/2 151/ 181/2 211/ 25 Inches 11 12 13 14 15 16 17 18 19 20 Gallons 281/4 311/2 34 37 403/4 433/ 46/ 491/2 521/4. 541/4 55 20% For a 55-gallon drum in a vertical position, each inch represents about 1.7 gallons. Filling Tank with Spray Pump The pump on the sprayer may be used to fill the tank as follows: 1. Remove suction line from tank and place it in the water source (creek, pond, or supply tank). Be sure to have suction strainer on suction line. [23] 2. 3. 4. into 5. Unscrew the pressure regulator to drop pressure to 0-20 p.s.i. Keep by-pass hose in tank to be filled. Engage pump and water will flow through the by-pass hose tank. Re-set pressure regulator after tank is filled. Caution About Using 2,4-D and 2,4,5-T A sprayer that has been used to apply 2,4-D or 2,4,5-T should not be used for applying insecticides or fungicides to broadleaf plants such as cotton, soybeans, and vegetables. Even if the sprayer has been thoroughly flushed with clean water, there is likely to be enough 2,4-D or 2,4,5-T left to damage sensitive crops. However, the sprayer may be used to spray livestock. Do not spray 2,4-D or 2,4,5-T near sensitive plants, especially when the wind is blowing toward the plants. To reduce drift, use a low pressure and a large nozzle orifice to produce large droplets. In order that the text content be readily understood, it is necessary at times to illustrate or use trade names of products or equipment rather than involved descriptions or complicated chemical identifications. In some cases it is unavoidable that similar products on the market under other trade names are not cited. No endorsement of named products is intended, nor is criticism implied of similar products that are not mentioned.