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Ch. 6, pp. 13 - 19

[Application Equipment: equipment | using pesticides safely ]

Using the same sprayer equipment for weed control and then for insect control is neither safe nor desirable. No matter how well a tank is rinsed after use of a herbicide, a residue will be left in the tank and in the gaskets, hoses and parts. If the same tank is then used with an insecticide to spray a plant, it is possible to kill the plant with the herbicide left in the tank. The wisest policy is to maintain two sprayers, one for herbicides and another for insecticides and fungicides. Have them clearly labeled according to use. Always wash after each use.
Pesticide application equipment comes in all shapes, sizes, types, and prices. Select equipment according to common sense.
Hose-End Sprayer
Proportioner or Hose-End Sprayer:
These inexpensive small sprayers are designed to be attached to a garden hose. A small amount of pesticide is mixed with water, usually no more than a pint, and placed in the receptacle attached to the hose. A tube connects this concentrate to the opening of the hose. When the water is turned on, the suction created by the water passing over the top of the tube pulls the pesticide concentrate up and into the stream of hose water. The stream can reach into medium-high trees if water pressure is high. Problems are encountered from poor spray distribution and clogging of nozzles. The metering out of the concentrate into the stream of hose water is very inaccurate, since it is determined by the water pressure. Proportioners put out an excessively high volume of spray for most needs, using excessive pesticide. These sprayers are popular due to low cost, but the low purchase price is quickly negated by the cost of excessive pesticides used. All hose-end proportioners should be equipped with an antisiphon device to prevent back-siphoning of toxic chemicals into the water system.
Trombone Sprayer
Trombone Sprayer:
The trombone sprayer is a medium-sized, hand-held piece of equipment. A spray mixture in the correct dilution is prepared in a container such as a bucket. The intake tube of the sprayer is inserted into the mixture in the bucket. Pump pressure is created by operating the sprayer in a trombone-like motion. The pesticide is pulled up the hose and out the end of the sprayer. A uniform concentration of the spray can be maintained, since the pesticide is mixed with a known quantity of water. When using a wettable powder, agitate the spray mixture frequently to keep it in suspension. Trombone sprayers are excellent for spraying trees and shrubs, are easy to wash and keep clean, but require some effort to operate.
Compressed Air Sprayer, Tank Compessed Air Sprayer, BackpackHand Duster
Compressed Air Sprayer (backpack or tank sprayer):
Spray is mixed in a small tank (generally 1 to 5 gallons) and the tank is carried over the shoulders. A hand-operated pump supplies pressure during application. A uniform concentration spray can be maintained since the pesticide is mixed with a known quantity of water. Frequent agitation of the spray mixture is necessary when using a wettable powder formulation. Applicator has excellent control over coverage, making this sprayer a good choice for treating dwarf fruit trees, vegetables, and ornamentals. Spray will not reach into tall trees. As water weighs approximately 8.23 pounds per gallon, small tanks are easier to use than large tanks.
Small Power Sprayers:
These have the advantage of being motor-driven, so the operator does not have to stop to pump up the tank. They are lightweight, since the spray in the tank is concentrated and diluted with air as it is sprayed. Power sprayers provide uniform pressure, but are generally too expensive for home garden use.
Hand Duster:
The duster may consist of a squeeze tube or shaker, a plunger that slides through a tube, or a fan powered by a hand crank. Uniform coverage of foliage is difficult to achieve with many dusters. Dusts are more subject to drift than liquid formulations due to their light weight and poor sticking qualities.


The usual approach consumers use when applying a pesticide over a given area is to mix a tablespoon or two of a certain pesticide and apply it to a problem area. This is acceptable if the label gives recommended rates in teaspoons or tablespoons per gallon. But some pesticides, specifically herbicides and insecticides for lawns, do not give rates in tablespoons or teaspoons per gallon. Instead, they give rates of application in teaspoons or tablespoons per 100 or 500 square feet. Unfortunately, the consumer all too often solves this problem by guessing how much to use. This can be dangerous; too concentrated may be too toxic; too little will not control the problem. It is irresponsible of the consumer to apply chemicals at improper rates. It is dangerous to him/herself, neighbors, and the environment.
A better approach is to calibrate the sprayer. The calibration of a home sprayer is relatively easy. Once it has been done, it has been done for the life of the sprayer, provided the nozzle remains unchanged, clean, and adequate pressure is used. It must be kept in mind that the rate at which the liquid is applied varies with the pressure and size of the opening in the nozzle. High pressure and a large opening in the nozzle permit more liquid to be applied over a given area than low pressure and/or smaller nozzle. For calibrating a sprayer, the procedure is as follows:
1) Fully pressurize the sprayer and determine delivery time. This is done by spraying water through the sprayer to fill a pint jar while noting the time needed to do so. Mark this delivery time on the sprayer for future use.
2) Calculate the area to be treated. Measure the area that is to be sprayed. Multiply length times width to determine the area of a rectangle. The area of a triangle is calculated by multiplying the base times the height and dividing by 2. Most areas can be calculated by combining rectangles and triangles or subtracting triangles from rectangles.
3) If the area is large, divide it into sections equal to the size of the delivery area.
Spray an area with water, at normal working speed, for 30 seconds. Measure the area sprayed. This tells how much area can be sprayed in 30 seconds and therefore the amount that is applied over that area (see item 1). For example, assuming that it has been established: 30 seconds of spraying delivers a cup and 30 seconds of spraying will cover 100 square feet; then 1000 square feet require 5 cups spray (5 x 10) delivered or, 1 quart + 1 cup or 40 ounces. If the label calls for 3 tablespoons of pesticide for 1000 square feet, then, 3 tablespoons of pesticide must be mixed with 40 ounces of water to achieve proper spray coverage. Many commercial-type chemicals are given in pounds to the acre or quarts to 100 gallons of water. To convert rates to equivalents used by a consumer, consult the pesticide conversion chart at the end of this chapter.
Either compressed-air sprayers or hose-end sprayers can be used. Hose-end sprayers do not meter out the pesticide as evenly as compressed-air sprayers. However, compressed-air sprayers do not maintain pressure as evenly as hose-end sprayers unless frequently pumped. Some hose-end sprayers will not continue to spray pesticide if the thumb hole is not covered. Other hose-end sprayers use a trigger device to control the spraying.
The spray pattern best used to cover an area of ground is one which will give uniform coverage with little spray overlap. Overlap can be a problem, causing certain areas to end up with an extra dose of pesticide. The spray pattern used to apply the pesticide should be continuous and uninterrupted. If a herbicide is being applied, the sprayer should not be slowed down or stopped at each weed. If the herbicide has been mixed correctly and the sprayer is properly calibrated, the continuous uninterrupted flow of chemical will be sufficient for good pest control. The spray pattern should be directed so that the applicator does not walk through it while spraying. The spray pattern should form an arc no more than 3 to 4 feet on either side of the operator. The sprayed area should have a small amount of overlap to ensure coverage. There can be a time when overlap may be beneficial. If good spray coverage is questionable such as when using hose end sprayers, cut the application rate in half and apply the pesticide first in an east-west pattern, then in a north-south direction. This gives better coverage with devices typically poor in their metering capabilities.
When the mixture on the label is in teaspoons or tablespoons per gallon and the plants are upright such as shade trees, fruit trees, shrubs, and vegetables, spray the leaves until pesticide solution drips from the leaves. Don’t forget to spray the underside of leaves for good coverage.
Single Application
Spray Pattern with a Single Application

Double Application
Spray Pattern with a Double Application


When applying pesticides, wear the protective clothing and equipment the label recommends. To prevent spillage of chemicals, always check application equipment for leaking hoses or connections and plugged, worn, or dripping nozzles before adding pesticide. Before spraying, clear all people, pets, and livestock from the area. To minimize drift, apply pesticides only on days with no breezes. If moderate winds come up while you are working, stop immediately. Reduce drift by spraying at a low pressure and using a large nozzle opening. Generally, the safest time of day to spray to reduce the hazard of drift is early morning. Vaporization is the evaporation of an active ingredient during or after application. Pesticide vapors can cause injury. High temperatures increase vaporization. Choose pesticide formulations that do not evaporate easily, and spray during the cool part of the day to reduce vaporization. Some products, like 2,4-D, are very volatile and can move for miles under favorable conditions. They should not be used near highly sensitive plants like grapes and tomatoes. Do not apply when it is windy nor when temperatures following application will reach above 85 degrees F.
Cleaning Equipment

Thoroughly clean all equipment immediately after use. Pesticides should not be stored mixed. If you have excess pesticide mixed which cannot be used, spray it over an area that it will not harm. Check the pesticide label to determine safe areas. Thoroughly clean all spray equipment inside and out with clean water. Don’t forget to flush the hoses and nozzles. Be careful that the cleaning water does not damage crops. Do not dump the rinse water in one place where it will be concentrated and may become a pollutant. Spray the rinse water over a broad area so that the pesticide will be further diluted. Never rinse pesticides down the drain!
To clean 2,4-D type herbicides from hand spray equipment such as a 3-gallon garden sprayer, use household ammonia. Thoroughly rinse the equipment with fresh water after spraying. Fill the spray equipment with an ammonia solution, using one cup of ammonia to 3 gallons of water. Let the equipment soak for 18 to 24 hours.
Always spray part of this mixture through the pump, hose, and nozzles at the beginning and end of the soaking period. NOTE: 2,4-D cannot be completely removed from a sprayer once used in it. Do not use this sprayer to apply other pesticides to desirable plants.
Storage and Disposal

Gardeners should store all pesticides in their original containers, in a locked cabinet. No exceptions if you are concerned about children's lives! They should be protected from temperature extremes, some can be damaged upon freezing, others can be altered by heat. Do not store pesticides in the home! Empty containers are best placed in refuse cans destined for a sanitary landfill. Wrap containers in newspaper and secure before disposal. Some counties have special chemical dumps for pesticides. The bottle should be rinsed out first, pouring the rinse water into the spray tank. Rinse three times, allowing 30 seconds to drain between each rinse. Never use empty pesticide containers for other uses, never allow children to play with empty containers. If possible, break the containers or punch a hole through the bottom before disposal. Do not burn paper containers.

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