Southeastern U.S. Vegetable Crop Handbook - 2021 - 38

pollination for two acres. Bumblebee hives should not be placed in
direct sunlight so that the bees work more efficiently. No more than
two bumblebee quads should be placed in one location so that pollination
is more uniform in the field. The quad locations should be at
least 650 to 700 feet from each other.
Insecticides applied while a crop is in bloom pose a serious
hazard to bees visiting flowers. If insecticides must be applied, select
a product that will give effective control of the target pest but
pose the least danger to bees. Apply these chemicals near evening
when the bees are not actively foraging and avoid spraying adjacent
crops while bees are active. If insecticide spraying is necessary,
give the beekeeper 48 hours of notice of when you expect to spray
so that precautions can be taken. Avoid leaving puddles of water
around chemical mixing areas as bees may pick up and be harmed
by insecticide contaminated water. As with honeybees, one must
carefully plan when to spray insecticides so that the bumblebees
are not injured or killed. Because bumblebees are most active from
dawn until late morning, and again from about 4 PM until sunset,
the hives need to be closed around 11 AM so that the bumblebees
remain in the hive and are protected during a late evening spray application.
HOW
TO IMPROVE PEST CONTROL
Failure to control an insect, mite, disease, or weed pest is often erroneously
blamed on the pesticide when the cause frequently lies
elsewhere. Several common reasons for failure to achieve control
are the following:
1. Delaying applications until pest populations become too large or
damage is too advanced.
2. Poor coverage caused by insufficient volume, inadequate pressure,
or clogged or poorly arranged nozzles.
3. Selecting the wrong pesticide for the target pests.
4. Contaminated or high pH water source.
SUGGESTED STEPS FOR MORE EFFECTIVE PEST CONTROL:
1. Scout fields regularly. Know the pest situation and any buildups
in your fields. Frequent examina tions (at least once or twice
per week) help determine the proper timing of the next pesticide
application. Do not apply a pesticide simply because a neighbor
chooses to do so.
2. Integrated Pest Management (IPM). Use an ongoing program of
biological, physical, cultural, and chemical methods in an integrated
approach to manage pests. IPM involves scouts visiting
fields to collect pest population data. Use this updated information
to decide whether insecticide applications or other management
actions are needed to avoid economic loss from pest damage.
Control decisions are based on factors such as:
* The economic action threshold level (when the cost of control
equals or exceeds potential crop losses attributed to real
or potential damage)
* Other factors are listed in the Recommended Control Guidelines
section that follows
To employ an IPM program successfully, basic practices need to
be followed. Whether participating in a univer sity- or grower-supported
IPM program, hiring a private consultant, or doing the work
personally, the grower still practices:
* frequent and regular examination of fields to assess pest populations
*
applying a control measure only when the economic threshold
level has been reached
* where possible, employing a cultural practice or a biological
control or using a pesticide that is less harmful to natural enemies
of the target pest
Resistance management. The way pesticides are used affects
the development of resistance. Resis tance develops because intensive
pesticide use kills the susceptible individuals in a population,
leaving only resistant ones to breed. Adopting the following
practices will reduce the development of pest resistance:
1. Rotate crops to a nonhost crop, thus reducing the need for pesticide
treatment and, thereby reducing the ratio of resistant to susceptible
individuals in the breeding population.
2. Use control guidelines as an important tactic for reducing the
pesticide resistance problem. For more informa tion concerning
control guidelines, refer to the following section and the
crop-specific sections of this handbook.
3. Spot treat when possible. Early-season insects are often concentrated
in areas near their overwintering sites. Diseases often can
be first detected in favorable microclimates, such as low or wet
areas of the field. Perennial weeds and newly intro duced or herbicide-resistant
annual weeds often occur first in small numbers
in a part of a field. Treating these areas, rather than the entire
field, can prevent the development of resistant populations.
4. Control pests early, because seedling weeds and immature insects
are more susceptible to pesticides and less likely to develop
resistance compared to older and more mature crop pests.
5. Do not overspray. Attempts to destroy every pest in the field by
multiple applications or by using higher than labeled rates often
eliminate the susceptible pests but not the resistant pests.
6. Rotate pesticides to reduce the development of resistance, particularly
with pesticides that differ in their mechanism of action.
Rotation among different chemical groups is an excellent method
of reducing resistance problems.
7. Use appropriate additives when recommended on the pesticide's
label. For example, adding a crop oil concentrate or a surfactant
to certain postemergence herbicides will increase the effectiveness
of the herbicides.
Control Pests According to Recommended Control Guidelines
or Schedule. Control guidelines provide a way to decide whether
pesticide applications or other management actions are needed
to avoid eco nomic loss from pest damage. Guidelines for pests
are generally expressed as a count of a given insect stage or as a
crop damage level based on certain sampling techniques. They are
intended to reflect the pest population that will cause economic
damage and thus would warrant the cost of treatment. Guidelines
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2021 Vegetable Crop Handbook for Southeastern United States
Southeastern U.S. Vegetable Crop Handbook - 2021

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