INTEGRATED PEST MANAGEMENT
Much has been written about Integrated Pest Management (IPM) and how
its implementation in agriculture and horticulture has reduced pesticide
use. Releasing beneficial insects, alternating toxic chemicals with more
benign ones to reduce insect immunity, and other elaborate programs are
being utilized by commercial operations. But what about the average
homeowner? Are these programs practical and are they affordable? The
average homeowner may not be aware of the many options available for
controlling insect pests in their yard. To most people the use of toxic
chemicals is the only solution that they are familiar with.
IPM for the homeowner can include many of the following methods:
beneficial insects, baits, cultivation techniques, mulching and use of
compost, controlled watering, and sanitation. These are all
environmentally-sound methods that can be used to create a successful
home-IPM program.
Beneficial insects are those that attack the insects that harm our
plants. The use of these "beneficials" to control harmful ones
is a great tool in the IPM arsenal if you have a large piece of
property, say five acres, or if the insects that you want to control are
in an enclosed area such as a greenhouse. In a small backyard the
beneficials that are released could get blown next door by the wind or
they could fly out on their own. That happens occasionally, so you may
want to add some other practical methods for controlling the insect
problems in your garden.
A useful beneficial for the homeowner is the nematode, microscopic
nonsegmented worms. A small percentage of these are damaging to plants,
but some are parasitic to various larva and grubs that can cause
extensive damage to plants. Beneficial nematodes can be utilized as a
soil additive in the control of many types of harmful insects.
Baits are also very practical for the home garden IPM. A good example
of a bait is what currently is used for fire ant control. Granules are
broadcast on the ground in areas that ants are known to occur, the ants
are tricked into bringing the granules back to the nest as food, and
when the granules are eaten, the ants are poisoned and die. This is an
effective method for controlling ants because liquid sprays will not
penetrate into the ant nest, so most of the ants, especially the queen,
are not killed. Many baits are relatively nontoxic to mammals and birds,
but will achieve effective control of grasshoppers, houseflies, and
other noxious insects. (A word on toxicity: every substance has the
potential to be harmful or toxic - even drinking water, when consumed in
great amounts. A non-toxic chemical, therefore, should still be used
judiciously.)
Cultivation techniques can also be used as an effective control for
certain insects. Spider mites, microscopic members of the spider family,
feed on the sap of plants. So do aphids and scale, members of another
insect family. These can be controlled by removing the most nutritious
food available, which is the sap in dying leaves or new growth (like
flowers and flower spikes). This is not to say that you should prune all
your foliage or flowers. In plants such as bananas, heliconias, gingers,
palms and other related plants, pruning the oldest leaves, the ones that
will yellow in a month or so, and the flower spikes when they emerge,
will reduce the areas that these insects like to feed.
Ants can often be a source of aphids and scale found on plants.
Certain species of ants actually farm these insects as if they were
cattle. The insects are placed in a favorable feeding site and are
protected from natural predators, such as wasps and ladybugs and their
larvae (beneficials), by the ants. In turn, the ants receive the excess
honeydew that is exuded from these sucking insects. Often the first
indication of scale on a palm or any other tree is the presence of ants
going up and down the trunk of the tree. If the ants are controlled at
ground level (using baits), there will be fewer insects feeding on the
tree. Without the ants' protection, these insects are more vulnerable to
their natural predators.
Mulching and the use of "finished compost" should be part
of the homeowner's IPM plan. The use of mulch controls weed growth,
helps keep moisture in the soil, and builds up a layer of humus. Humus
is the top layer of soil that is mainly decomposed organic matter and is
a natural source of plant nutrients. The soil found along the east coast
of South Florida generally has little organic material in it and will
benefit from the addition of humus. Most plants will benefit from the
addition of mulch on the soil. However, when adding the mulch, it should
not be placed within six inches of the plant's trunk. This prevents
"collar rot", a fungal condition that results from too much
moisture on the trunk.
Fresh mulch consists of uniformly-sized wood and plant debris that
has been passed through a wood chipper. It should be allowed to sit as a
pile for at least a month. The heat generated by the initial stages of
decomposition can reach over 130 degrees. Many pathogenic organisms are
killed at this level of heat, so there will be less of a chance that you
are importing something nasty to your garden. However, this heat can
also cause damage to roots underneath the pile and ultimately kill a
plant. In general, a composting pile should not be placed within 15 feet
of any plant.
Finished compost, having passed the final stage of aerobic
decomposition, can be a good planting medium. It will not break down any
more and has a microflora that is very beneficial to plants. In
addition, the microorganisms that brought about the decomposition are
still active and are still seeking a source of food, which in some
instances are fungi and nematodes that are harmful to plants.
Water is obviously a very important factor to plant growth. Whether a
plant is in a container or planted in the ground, a water balance needs
to be achieved. Once you have found this, many fungal problems can be
avoided. Too much water can cause some plants to rot, and too little
water can stress a plant enough to cause premature leaf drop and,
eventually, death. Even if a plant has wilted and then recovered,
permanent damage may have occurred to the stressed leaves, making them
more palatable and nutritious to certain insects (like spider mites).
Adequate drainage for the plants' roots will reduce the chances of
fungal problems. When you buy a plant at a nursery, there is probably
some peatmoss in the soil mix and orchids are often potted in pine bark
or tree fern. These soil amendments are good to grow certain plants in,
but they all break down after a year or so. This causes inadequate
drainage, leaving the plant roots wet most of the time, and with little
oxygen. Wilting leaves are sometimes an indication of too much water and
upcoming fungal problems.
Sanitation is a must in an IPM program. Unsterilized tools can
transmit viruses and fungi from one plant to another. For example, in
Florida, unsterilized pruning saws are transporting a fungi that is
fatal to Phoenix palms. Weeding is another important method of
sanitation. Not only does it look better, but removing unwanted plants
can also remove a potential source of food for harmful insects such as
White Fly, a minute fly that feed on the sap of plants. In South
Florida, some plants that we consider weeds are the primary host to the
types of insects that you would not want attacking your favorite plants.
These are some of the things that an average homeowner can do to
develop a fairly sophisticated IPM program for their garden. These
programs are practical. They are affordable, and they offer many
benefits, such as reducing the use of toxic chemicals and increasing
plant vigor.
Assoc. of Zoological Horticulture - Conference 1991
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