If applicators use too much pesticide, the following problems can result:
• The crop can have more residue than the law allows, which can
pose health hazards to consumers and could prevent the crop from
entering the market until it has undergone special cleaning.
•
and destroyed without any compensation to the grower. Resulting
negative publicity can harm the future markets for that commodity.
• Reentry by workers into overdosed areas could be dangerous and
lead to illnesses, medical costs, and liability to the grower.
•
• Phytotoxicity is more likely to occur.
It is important not to exceed the label rates. If the maximum labeled rate is
not achieving the desired results, look for other reasons for failure, such as
poor coverage or resistance to the insecticide in the target insect population.
Step 3: Apply pesticides at the right time.
The chosen pesticide should be applied at the correct time. This is one
apply chemical control is a very dynamic undertaking. Failure to treat at
or near the correct time is one of the major reasons for unsuccessful pest
management.
• Growers should regularly and thoroughly inspect the crop so that
they are aware of the presence of insects and mites as well as any
increase in numbers.
• Growers should know the pest, its behavior, and its ability to damage
the crop.
• Growers should be aware of the number of insects or mites that
constitute an economic or action threshold. Thresholds for each pest
where information is available are discussed later in this document.
• Growers should know the biology of the pest so that insecticide or
miticide application can be aimed at the weakest, most vulnerable
stage or size. Some stages of insects and mites, such as the egg
stage, can seldom be controlled. Young larval or nymphal stages are
more easily controlled and require less insecticide or miticide than
older stages. Pesticides generally do not affect pupae (large larvae
It is generally best to apply pesticides in the late afternoon or evening
hours when temperatures start to decrease. This also allows for maximum
exposure before “airing” out the sprayed area for employees. Also, many
insects are most active at night. The risk of phytotoxicity is greater when
applications are made during the middle of the day when temperatures are
high. However, it has been reported that better mite control can be achieved
by spraying early in the morning hours. As a rule, insecticide or miticide
applications should be made while temperatures are low. Pesticides should
not be applied when plants are water-stressed.
Step 4: Apply pesticides correctly.
Proper application, like proper timing, is one of the most important steps
properly and then fail to deliver the material to the target area. There are
many factors and components of spray methods that add up to proper
application of pesticides.
Spray equipment must be properly calibrated. A calibration mistake can
result in applying too little pesticide and not achieving control, or applying
too much, which is wasteful and illegal.
Growers should purchase the proper type of equipment to meet the
needs of the operation and use equipment designed for the target pest.
Each pest differs in habits and behavior, and a single piece of equipment
may not meet all needs.
High-volume sprayers are popular and have been used for years. They
their operation. However, high-volume sprayers require a great deal of labor,
are time-consuming to use, and are considered to be low in application
e
reaches the actual target when using high-volume systems. However, most
insecticides and miticides are labeled for high-volume application.
For best results, knowledge about the pest and its biology should be
coupled with the capabilities of the equipment. To reach the bottom sides of
the leaves in thick canopy crops, a driving, directed spray may be required.
If the crop canopy is thin, a rolling fog, atomizer, or electrostatic applicator
may be very effective. Many insecticides can produce vapors that aid in
controlling insects even when the coverage is less than desired. However,
proper coverage can further enhance their fumigating properties.
Another consideration when correctly applying insecticides and
miticides is the proper maintenance of spray equipment. Many spray
operations are hampered and their effectiveness drastically reduced
because the spray cannot be delivered at the proper pressure, droplet
size, or pattern due to excessive wear, improper adjustment, or broken
or improperly working parts. Growers should regularly check nozzles
and discs for wear and tear and replace them when they do not meet
and wettable powder formulations are used. Workers should be aware of
spray pressure and have accurate gauges. Inaccurate pressure—even
small errors—can result in improper droplet size and failure to deliver the
desired coverage. Equipment upkeep also factors heavily in the overall
success of spray operations. Most insecticides are highly corrosive and
will react with hoses, lines, nozzles, tanks, and other components. The resulting
corrosion affects the spray patterns and also leads to the formation
of foreign particles that clog the equipment. Applicators should use the
spray as soon as it is mixed and thoroughly clean and rinse the equipment
Workers must mix only the spray that is needed for the job. Leftover
spray allowed to sit in the sprayer can quickly destroy it and other sprayer
parts, lines, and components. Leftover spray also must be carefully and
legally disposed of, by application to a labeled site. Disposal of pesticides
is a growing concern, with liability becoming more of a problem. Therefore,
growers need to plan carefully for the amount of pesticide they need, use
what is mixed, and clean up properly afterward.
Spray equipment must be properly stored after cleaning to keep it free of
dust, dirt, and other foreign materials. Rust particles, pieces of rubber lines,
and other unwanted particles can quickly stop up a system or cause poor
spray patterns, particularly when pressure is applied.
Clean water should be used for spraying. Water is the most commonly
used diluent (carrier) for pesticide sprays. Water frequently contains dirt,
sand, or corrosion from the pipes or lines that may enter the spray tank.
Loading hoses or pipes can be dirty. These contaminants can cause
as possible to ensure freedom from contamination. Filters should be used
between the source of water, the spray tank, and where the water enters
capabilities of the equipment.
Pesticides should be used as soon as they are mixed. Once mixed with
water, the pesticide begins to change. The effective life of certain pesticides
can be only hours once they are mixed with water. Water with a pH over
7.0, which is neutral, can be particularly detrimental to many pesticides.
Generally speaking, the higher the pH, the faster the pesticide is broken
down and rendered useless. Under Florida conditions, where the underground
water is frequently high in calcium carbonate with resulting water pH
longer than necessary.
22 2019 Vegetable Production Handbook of Florida