The use of pesticides is an essential part
of agricultural production, whether field crop, livestock, orchard or greenhouse. Precautions
should be taken with handling pesticides in any operation but applying pesticides in a
greenhouse requires some additional precautions. Greenhouse operations are unique because you
work in a closed environment and because space is limited, you are likely to come in contact
with treated foliage. Pesticides do not settle out quickly because air movement is sometimes
kept to a minimum. A preventative spray schedule is part of good management. It may contain
many different pesticides used at various stages of production. There are many factors
which affect your exposure. You have little control of factors such as the pesticide used,
the crop grown and the climate in the greenhouse. You do have control over, the application
schedule plan, the protective clothing used, the safety procedures followed, the method
of application chosen and when the plants will be handled. The choices you make concerning
these factors will affect your exposure. There are three major methods of application used,
high volume spraying, granular applications, and low volume spraying. It’s your responsibility
to apply pesticides safely to reduce exposure to yourself and fellow employees. Let’s
look at one of the most common methods of application, high volume spraying. It involves
the use of large volumes of water and high pressures between 300 to 600 PSI. High volume
sprays are hazardous because you’re required to handle pesticides for extended periods
of time and applications are usually made during the day when workers are nearby. To
protect other employees, spray in the early morning or late evening when no one is around.
Before using the pesticide, read the label for specific instructions on the proper selection
of protective clothing and equipment. For greenhouse workers this will normally include,
rubberized rain gear, boots, gloves and hat and of course a respirator. Before beginning
to mix and load, check all the equipment for any defects. A spot check of pressure hoses,
by-passes and valves and all other equipment should become part of a weekly safety routine.
When mixing and loading, you’re handling materials in concentrated form. Here you have
a greater chance of being exposed to dangerous amounts of pesticide. Your tank and mixing
area should be well lit and properly ventilated. Use a sharp instrument to open containers,
measure on a stable surface below eye level. Be sure to accurately weigh powder formulations.
Accurate calculation and measuring ensures that very little if any spray solution will
be left over. Recheck the label for instructions on mixing and loading. Some pesticides can
be added directly to the tank while others must be pre-mixed. If you’re using liquid
pesticides like these, be sure to use a well-marked, clearly labeled measuring device such as a
graduated cylinder. Rinse the empty containers and the measuring cup at least three times.
Put all the containers and measuring devices away until the time of proper disposal. The
tank supply line should be equipped with a valve or an air gap should be maintained between
the hose and the solution level to prevent siphoning into the water supply hose when
the pump has been shut off. If siphoning should occur, the water supply hose would be unfit
for any use. Only use the hose that has been designated for filling the tank. Make sure
everyone is out of the area before beginning to spray. Always start spraying at the furthest
end and work backwards, spraying both sides as you go. Your exposure will be lower than
if you had walked back through the treated area. There’s a great deal of multi-level
spraying in a greenhouse. Assess your own situation and decide the best way to protect
yourself. When spraying overhead plants, be sure to wear protective head covering and
pay particular attention to the protection of your arms. When spraying overhead plants,
tuck the sleeve inside the cuffed glove. When spraying lower plants tuck the cuffed glove
inside the sleeve. How you apply your pesticides and the safety precautions you take depends
on the products formulation, such as emulsifiable concentrates, wettable powders or granulars.
The application of granular pesticides requires you to use some specific safety procedures.
Dust produced during application is extremely hazardous. If you avoid producing dust when
applying granular formulations, you can reduce exposure by inhalation. The chance of dermal
contact is also reduced. There are some things to watch for when applying granular pesticides.
Clothing should fit properly so that individual granules do not lodge in cuffs and pockets.
Clothing without cuffs or pockets would be ideal. If treated pots or plants must be handled,
wear protective clothing and gloves. Keep runoff water from contaminating walkways and
work areas. Read the label of each pesticide so that you are aware of any special precautions.
Another common method of application is low volume spraying using mist blowers, thermal
foggers or smoke fumigators. Mist blowers carry concentrated pesticides which are suspended
as fine droplets. When mist spraying, pesticides are ten to twenty times more concentrated
than those used in hydraulic sprayers. You should always exercise extreme caution when
applying pesticides with mist blowers, thermal foggers or smoke fumigators. Before low volume
spraying, close all doors, windows, ventilators and other openings to the outside. Make sure
that all employees have left the greenhouse and post warning signs at all entrances. Do
not remove these signs until the airing out period is complete. Lock all entrances to
prevent entry from anyone other than you or your assistant. An assistant should always
be available during application in case of an accident. If you’ll be smoke fumigating,
take some time to plan the procedure with assisting employees. Assign a person to each
aisle to place the containers. The employees should ignite the containers simultaneously,
then leave quickly. Whether you’re fumigating, fogging or mist spraying, the area should
remain sealed for the period of time specified on the label. Then air out the greenhouse
before anyone enters. When airing out the greenhouse, inform people
working outside to keep away from exhaust fans. Check the label to find out how soon workers
can handle plants after an application and how soon plants can be sold to consumers.
Some pesticide labels state a minimum interval between application and re-entry into treated
areas. Occasionally an employee may question you concerning re-entry. Keeping a record
of all application dates, rates and methods used will verify the spray schedule and provide
legal evidence if a dispute arises. Common sense should be used when spraying any pesticide.
Here’s a summary of the basics. Always read the label before use. Never eat , drink or
smoke while spraying. If it is necessary to stop for lunch, wash before eating. Store
pesticides under lock and key. Never leave equipment or empty containers lying around.
Empty containers should be disposed of properly and made impossible for reuse. No employee
should handle pesticides unless trained in their proper use. At the end of any application,
equipment must be cleaned, protective clothing and equipment washed, dried and stored and
the employees should shower and change clothes. Everyone benefits when pesticides are used
safely by well trained employees. Accidents are avoided and pesticides related illnesses
are reduced. The efficiency of your operation can only
be improved by using the safety procedures we mentioned in this program. By using them,
you’ll be making your working environment a safer place for you, your employees and
your customers.