Group Title: Gardeners factsheet no. 19, October 1979, Revised Nov. 1979
Title: Organic gardening : pest control
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Permanent Link: http://ufdc.ufl.edu/CA01300612/00001
 Material Information
Title: Organic gardening : pest control
Series Title: Gardeners factsheet no. 19, October 1979, Revised Nov. 1979
Physical Description: Book
Language: English
Creator: Ivie, Michael
University of the Virgin Islands. Cooperative Extension Service. ( Contributor )
Affiliation: University of the Virgin Islands -- Cooperative Extension Service
Publication Date: 12/26/1979
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Subject: Caribbean   ( lcsh )
Spatial Coverage: North America -- United States Virgin Islands
Caribbean
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Bibliographic ID: CA01300612
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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GARDENERS FACTSHEET NO. 19
OCTOBER 1979
Revised Nov. 1979













ORGANIC GARDENING: PEST CONTROL
by
Michael Ivie
and
Walter Knausenberger


Organic pest control is as old as agriculture itself. Recently
(since World War II) it has been replaced in the developed
countries by pest control based on man-made pesticides. Today,
many people in the Virgin Islands and elsewhere are returning to
the organic gardening strategy, rejecting or restricting the use of
man-made pesticides. Some are totally opposed to the use of
these pesticides, some only oppose their use on food crops and
many simply aim to minimize their use as much as possible.
There are many excellent reasons to utilize the organic
gardening strategy. An Important one is that insect pests are
"left alone" genetically, because there is no pressure placed
upon them by pesticides, so they are not continually selected to
become resistant "super bugs". Organic methods are generally
less polluting and blend into the surrounding ecosystem rather
than disrupting it. Also, because many pesticides are
petrochemical derivatives, their costs are increasing, making
alternatives more attractive. Whatever the reason, philosophical,
ecological, or economic, the organic gardener must be ready to
work to make up for the loss of those weapons he chooses not
to use.
Organic gardeners have a variety of effective non-chemical
weapons against garden pests. They fall into several broad
groups:
1. Varietal Selection
2. Cultural Control
3. Physical Control
4. Plant-Derived or Natural Poisons
5. Biological Control
6. Home Remedies

VARIETAL SELECTION is often the easiest way to avoid
pest problems. It is the only effective way to deal with plant
diseases, without pesticides. Plant breeders are continually
producing higher yielding varieties that are more resistant to
diseases, insects and nematodes. When reading the seed
packages or catalogs, look for mention of resistance to pests or
diseases. Information on the most up-to-date varieties can be
obtained through your local Extension Agent.
CULTURAL CONTROLS simply involve changing your


gardening practices to reduce the hospitality your garden offers
pests. Removing or burning diseased plant material (sources of
infection), such as corn smuts, and destroying weeds and plant
debris that serve as hiding places for insects, such as the corm
borer in rotting banana stumps, can do a lot towards minimizing
pest problems in the next crop.

Staking to keep fruits off the ground (see Gardeners
Factsheet 7), pruning off diseased limbs, removing sickly plants,
proper soil building (see Factsheets #6 & 18), planting on raised
beds in the rainy season and in furrows in the dry, are all cultural
practices that help control diseases and pests.
Rotating crops from one location to another in the garden
can control problems of nematodes, soil insects and disease
build-up. An easy way to do this is divide your garden up into
blocks rows or squares and number them. Then group the
crops you grow into botanical families (see table below). At
successive planting times, change the families to different
blocks.
Crop rotation requires planning and forethought, as well as
some record-keeping, to be effective. However, to the organic
gardener few things can be as effective as a good rotation plan.



































An example of crop rotation plan for a small garden with four
crops.


TABLE 1


Certain rotations work best. For example, don't plant
tomatoes after cucumbers. Cucumbers give off a toxin that
discourages some other plants from growing around them. This
property can be used to advantage in companion planting, but
tomatoes are sensitive to the toxin and don't get started well
after cukess".




Plant a member of the bean family after high nitrogen
users such as corn or sugar cane. Organic gardens are often
short of nitrogen. Beans, peas, and other legumes are able to
"fix" their own nitrogen from the air, therefore they are not as
sensitive to nitrogen-depleted soils. They can, in fact, even add
some nitrogen just by having been planted there.



Don't plant two root crops consecutively in the same bloc .
Some insects and nematodes will feed on many different types of
fleshy roots. Remember, vigorous plants are better able to
withstand insect attacks. Deficiency symptoms of malnourished
plants should not be mistaken for pest damage.


SOME COMMON GARDEN CROP FAMILIES


NIGHTSHADE FAMILY -Solanaceae HIBISCUS FAMILY -Malvaceae SQUASH FAMILY -Cucurbitaceae

Tomato Hibiscus Melon
Peppers Okra Cucumber
Eggplant Sorrel Pumpkin
Tobacco Cotton Squash
White Potato Ghourds
Wild Nightshade Chayote




LEGUME (BEAN) FAMILY -Leguminosae LILY FAMILY -Liliaceae GRASS FAMILY Gramineae

Green Beans Onions Corn
Dry Beans Garlic Sugar Cane
Peas Shallots Sorghum
Pigeon Peas Chives Guinea Grass
Tantan Leek Bamboo



COLE FAMILY-Cruciferae CARROT FAMILY- Umbelliferae ROOT CROPS-Various Families
Cabbage Carrot Carrot
Kale Parsley Tannia
Broccoli Dill Dasheen
Collard Greens Anise Cassava
Kohirabi Fennel Sweet Potato
Radish Parsnips Yam
Cauliflower Celery Radish
Beets Ginger






PHYSICAL CONTROL involves exclusion or removal of
pest individuals by various means. Many people find physical
control repulsive, but for many pests in small plots it is very
effective. Commonly it involves simply looking over your plants
carefully, picking off pests, and destroying them physically
(usually under a well-placed shoe). For fruitworm, stinkbug,
frangipani worm, horn-worm, snails, and any other large "bugs"
it is easy, safe, visibly effective, and vengeful! Placing net or
screen enclosures over plants, and washing plants off are other
physical controls that can be used effectively. Additional
options include the use of fire, sticky barriers, and light traps.


THE PLANT DERIVED OR "NATURAL" POISONS
are used by organic gardeners under the theory that "if it's
natural, it's safe". Many of our most deadly poisons are plant-
derived or have natural analogs. Natural pesticides should be
used with every bit as much caution as synthetic pesticides.
Often their toxicity is as high as, or higher than, the synthetics.
Compare the LD,,'s* of commonly-used organic pesticides with
some common synthetic pesticides in Table 2 (the smaller the
number the more toxic).



Among the widely-used natural pesticides that are relatively
non-toxic are light oils, such as Volck Supreme oil. These are
very good tools for the organic garden, as they control mites,
aphids, mealybugs, scales and other small sucking insects better
than most other organic means.





*LD5o is a term meaning lethal dose per individual needed to kill
50% of a given population, determined by feeding to test
animals.


BIOLOGICAL CONTROL is a method much talked about
but little understood. It is the use of predators and parasites of
pests to keep pest populations down. Some people think that by
leaving your garden alone it will achieve its "natural balance"
through biological or natural control. There are several problems
with this idea. Man has transported plants and pests around the
world from their native homes. Often he has not taken the pests*
natural enemies with him.

The native home of the pest may be hard to find since bio-
control keeps it rare there, and it and its enemies are often
overlooked. Natural enemies that are found, often cannot be
introduced because they might attack a related beneficial insect,
or be otherwise harmful. Even when natural controls are holding
down the pest population, the pest's natural population levels
may be too high for us to tolerate on food crops.

However, with these limitations in mind, biocontrol can be a
valuable tool for the organic gardener. Choosing control
techniques to maximize predator and parasite populations is a
must for the organic gardener. These often tiny helpers run
around and perform free physical control of pests and as such
are valuable allies.

Buying ladybird beetles ("ladybugs") is usually a waste of
money due to the habits of the beetles. Many companies sell
Hippodamia convergens, a common species, because annual
congregations make collecting easy. These beetles are then kept
in cold storage until sold. The problem is that it is a behavior trait
of this species to fly a good distance before laying eggs, so that
you get few to stay in your garden. Other species are available at
considerably higher costs that are more effective, but even with
these, it is doubtful that the average Virgin Island gardener
buying mail-order ladybirds will be rewarded with an economic
control.


TOXICITY TO
Mammals Birds Fish


PERSISTENCE (days)
Plants Soil


PLANT-DERIVED
Nicotine
Pyrethrum
Rotenone
Ryania


55
200
200
1200


High Slight
Moderate Slight
Moderate Slight
Slight High


SYNTHETIC


Cygon
Diazinon
Carbaryl (Sevin)
Malathion


225
300
500
1375


Moderate
Moderate
Slight
Slight


Slight
High
Slight
High


Information taken from: Agricultural Chemicals, Book 1, Thomson, 1977; Agriculture Handbook #554 USDA, 1979; Northeastern Regional
Pesticide Coordinators, Pesticide Information Manual, 1972


TABLE 2


PESTICIDE


PESTICIDE TOXICITY


LDso
(mg/kg)


High
High
High
N.A.


1 1
1 1
1 1
1-3 1-7


High
High
Slight
High


7-21
7
2-10
1-3


21-28
10
21
1






Green lacewing eggs have a better payoff, though problems
here too are common. These eggs must be placed in small groups
on* the leaves of the affected plants (the larvae are
cannibalistic). Often the eggs are dead upon reaching the Virgin
Islands, or have already hatched and eaten each other.


The green lacewing. Larvae of this insect are voracious aphid
hunters.

Praying mantises are the worst investment. They are
cannibalistic, may wander off, and may eat as many beneficial
insects as harmful ones. Also the mongoose and toads seem to
find them tasty, and few survive very long.
It's important also to be aware that many of our familiar
fellow creatures are out there doing us a favor by seeking insect
pests as food. Very significant to us in the V.I. are the many
lizards and toads, both expert insect predators. Not to be
overlooked are the benefits provided by insectivorous birds,
bats, and spiders.

The best news in centuries for organic gardeners is the
development of the microbial pesticides. Increasing public
concern about pesticide poisoning and environmental impact
has lead to strengthened pesticide laws. This has spurred the
search for control methods that combine the assured, easy
control advantage of the synthetic pesticides with the safe,
environmentally clean organic school. Microbial pesticides are
naturally-occurring bacteria and viruses that attack only certain
insects (and can affect practically nothing else). They are as
specific to each type of insect as a key is to a lock. This allows
one to utilize these already existing systems to tip the natural
balance in our favor without resorting to synthetic chemicals.
These organisms are already associated with our gardens, so all
we will be doing is to multiply and use them.
As an example, Bacillus thuringiensis, called BT, is a
bacterium that harms only moth and butterfly larvae (caterpillars)
with an alkaline stomach, such as hornworms. Live spores of
these bacteria are grown and packaged to be sprayed on the
plant like an insecticide. The caterpillars eat the spores which
multiply inside and kill them. BT is so harmless that predacious
insects can eat the dead or dying caterpillars without harm.
Some organic gardeners shy away from these control
agents because their packages, consistency and application
methods remind them of synthetic chemicals and they equate the
two. However, as proof of the "naturalness",
you can apply the bacteria to a hornworm-infected plant, and


later pick off the dead and dying caterpillars. Then, put them in a
blender with water, strain the resulting mess and spray the liquid
on more hornworms. They too will die. Why? The bacteria are
eaten by the caterpiller and multiply inside by the millions. Each
caterpillar then can cause the death of other caterpillars,
organically.
Your best method is to learn to know your "bugs". Know
the harmful ones, but also learn about those which are beneficial
and accidental. Don't destroy the "good guys" and parasitized
"bad guys". Your local Extension Agent can help you learn to
identify them.


A parasitic wasp laying an egg in an aphid.


Under HOME REMEDIES are classed all those recipes and
imaginative techniques suggested in the popular organic
gardening literature. Some, such as neem seeds, black pepper
sprays (both insect feeding repellents) and beer baits (snail trap)
have already moved into the scientifically proven side. Others
such as companion planting and moon-coordinated planting are
currently being tested. However, some methods are simply
wishful thinking or pure hocum.
But how do you know which is which? First, does the method
have any objective experiments to back it up? Second, if based
on only casual observations, were they made in a way that
makes their conclusions logical, or could the conclusions have
resulted from totally unrelated factors? Third, is the method
safe? For instance, pouring salt on snails kills them, but it can
also kill plants whose roots absorb the salt later.
The organic gardener should have a pest control plan for his
specific garden location, crops and pests. A good plan always
involves regular inspection of the garden to enable one to spot
pest problems early. Make it a habit, and you will have taken an
important first step toward successful organic pest management.
In conclusion, organic pest control is effective with certain
qualifications. The practitioner must be willing to work hard,
learn about garden pests their appearance, life cycles,
enemies, and habits -judiciously-read organic gardening
literature for methods that might work, and accept some pest
damage. The rewards of healthful food, monetary savings, and a
sense of accomplishment make these challenges well worth the
effort to many thousands of organic gardeners here in the Virgin
Islands and the world over.


Products and suppliers mentioned by name in this publication are used as examples and in no way imply endorsement or recommendation of these products or suppers

Issued in furtherance of Cooperative Extension work, acts of Congress of May 8 and June 30, 1914 (as amended), in cooperation with the U S Department of Agriculture, D S Padda,
Director, College of the Virgin Islands Cooperative Extension Service The College of the Virgin Islands Cooperative Extension Service is an Equal Opportunty/Affirmative Action
organization, providing educational services in the field of agnculture, home economics, rural development, 4-H youth development and related subjects to all persons regardless of
race, color, relhgon, sex or national origin




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