[PDF]Organic Vegetable Gardening-24pp

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I. What is Organic Gardening? 4

A. Organic Gardening and Pesticides 4

B. Organic Gardening and Fertilization 4

II. Why Garden Organically? 4

A. Quality 4

1 . Nutrition 4

2. Taste 4

3. Pest Damage 4

4. Residues 4

B. Soils 4

C. Psychological Effect 5

EH. Limitations of Organic Gardening 5

A. Lack of Organic Alternatives 5

B. Climatic Effect (geographic and

annual) 5

C. Population Cycles 5

D. Inability to Tolerate Damage 5

E. Cost of Produce 5

F. Sources of Nutrients and Organic

Matter 5

IV. Alternative Means of Pest Control 5

A. Choose Vegetables and Varieties Wisely 5

B. Grow Resistant Varieties 6

C. Grow Hybrid Varieties 6

D. Obtain Quality Seed and Transplants 6

E. Use Cultural Controls 6

F. Eliminate Plant Debris 7

G. Increase Soil Organic Matter 7

H. Rotate Plant Families 7

I. Avoid Stress 8

J. Try Companion Planting 8

K. Use Intercropping 8

L. Time Plantings Carefully 8

M. Time Irrigation Properly 8

N. Provide Air Circulation 9

O. Use Mulches 9

P. Consider Using Solarization 9

Q. Avoid Introducing Pest Problems 1

R. Use Plant Supports 1



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V. Other Alternative Means of Pest Control 1

A. Barriers 10

B. Repellents 12

C. Traps 12

D. Baits 12

E. Birds 12

F. Beneficial Insects 1 3

G. Handpicking 13

VI. Protective Chemicals 1 4

VII. Natural Protective Substances 1 4

A. Water 14

B. Bug Juice 14

C. Hot Pepper 15

D. Soaps 1 5

E. Oils 15

F. Microbial Agents 1 5

G. Sulfur 15

H. Copper 15

I. Other Protective Chemicals 1 5

J. Botanically-Derived Chemicals 16

VIII. Managing Soil Organically 16

A. Introduction 16

B. Maintaining or Increasing Soil Organic Matter 1 6

C. Using Crop Residues 17

D. Crop Rotation 17

E. Green-Manure Cover Crops 1 7

F. The Effect of Mulches on Soils 18

G. Making and Using Compost 1 9

IX. Using Lime and Organic Fertilizers 20

A. Increasing Soil pH 20

B. Adding Nutrients — Manure 20

C. Adding Nutrients — Non-manure 21

D. Soil Amendments 22

X. References 22



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David W. Sams, Professor, Plant & Soil Science

Darrell D. Hensley, Assistant Extension Specialist, Entomology & Plant Pathology




Vfoat is Goganic Caicbiing?

There is considerable discussion, even among
those claiming to be organic gardeners, as to exactly
what constitutes organic gardening. Generally,
however, organic gardening is a system of gardening
that attempts to use only sustainable, ecologically
sound gardening procedures. Organic gardening
generally differs from traditional gardening in two
important ways: use of agricultural chemicals and use
of artificial or processed fertilizers.

Commercially, organic growers in Tennessee are
certified by the Tennessee Land Stewardship Associa-
tion. There are currently three levels of certification.
More information may be obtained from T.L.S.A.,
P.O. Box 328, Bell Buckle, TN 37020

Organic Gardening and Pesticides

Organic gardening rejects the use of all artificial
agricultural chemicals, including pesticides used to
control insects, diseases, weeds and nematodes, as
well as other agricultural chemicals used to affect
physiological processes and conditions such as
flowering, fruit color and firmness. Organic gardeners
differ concerning which, if any, naturally derived
pesticides are permissible and when and how they
may be used. Recent trends have been toward using
fewer pest control agents in organic gardening,
regardless of their origin.

Organic Gardening and Fertilization

Most organic gardeners consider soils to be a
living, biotic system and reject artificial chemical
fertilizers as too harsh to be applied to living soils.
Organic gardeners emphasize building soil organic
matter and then rely on natural sources of supplemen-
tal nutrients.

V\hy Snk Organically?
Quality

Organic gardeners generally feel that organically
grown food is superior to non-organically grown food
with respect to one or more components of quality.
Some would argue that organic food has higher



nutritional quality or better taste; however, there is no
evidence to support this. Since plants take up nutri-
ents dissolved in water as ions, and ions from all
fertilizer sources are identical, there is no reason to
suspect taste or nutritional differences directly
because of nutrient source. Organic fertilization can,
however, affect soil organic matter content, structure,
moisture retention and nutrient release. Some of these
may affect plant vigor, cell size or content, thereby
indirectly affecting nutritional quality or taste. Very
possibly, any effect on nutritional quality or taste is
the result of organically grown vegetables being
locally grown and thus fresher. Both nutrient content
and taste are generally at a maximum at harvest and
decline thereafter.

Many people garden organically partially because
of concern over pesticide residues on food, or in soil
or groundwater. However, careful use of pesticides
according to their labeled instructions need not leave
residues in soils or groundwater. Furthermore, the
residues found in food are generally believed to be
much higher than they really are. One should also
remember that residue tolerances for food are gener-
ally set at only 1/100 of the amount thought to be
harmful.

A discussion of the effect of organic gardening on
food quality should not end without mention of insect
and disease damage. Organic gardeners are generally
willing to tolerate some damage that traditional
agriculture perceives as reduced quality. Organic
gardeners generally feel occasional insect or disease
injury or reduced color and shelf stability are worth
the environmental benefits of growing vegetables
organically.

Effect on Soils

There is little doubt that organic gardening
improves soils because of the emphasis on increasing
soil organic matter. Increased soil organic matter
improves soil tilth and structure, improves water
retention, evens out nutrient release and may reduce
erosion and run off. It should be pointed out, how-
ever, that the heavy applications of manure sometimes
used by organic gardeners can create their own run-
off problems.



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Psychological Effect

A final reason for organic gardening, and perhaps
one of the best reasons, is that it helps some people
feel safer. When gardening organically, they no longer
worry about damaging their environment or family
with chemicals. There seems to be little harm in this,
as long as gardeners realize that even organic prod-
ucts must be used as they are designed and labeled to
be used and can be harmful if misused.

Iimitaticns of Qrcpnic GtofeniiTg
Lack of Organic Alternatives

Some pest problems are easily controlled by
organic alternatives. Others are controlled only with
difficulty or have no reliable organic controls. Some
crops either must be avoided by organic gardeners or
these gardeners must be willing to risk significant
losses from pests.

Climatic Effect

Climate varies regionally and annually. A pest
may pose little or no problem in one climate but be a
severe problem in another. Aphids, for example,
require high humidity to shed their skins and are not a
severe problem in regions of low humidity. They are,
however, a severe problem in Tennessee and much of
the humid Southeastern United States.

Even within a single state, climatic factors vary
with altitude, nearness to bodies of water, slope of the
land, etc. These differences also affect plant suscepti-
bility to problems and limit the effectiveness of
organic controls as well as chemical controls.

There are also annual climatic differences which
affect host and pest. An organic control measure that
works well one year may not work well the following
year because of this climatic variation.

Population Cycles

Natural populations tend to expand until they are
limited by their food supply or by another organism.
An insect species, for example, may have only
scattered individuals in an area, but have ample food.
Its numbers increase rapidly for a few years and it
becomes abundant. It then either consumes most of
the available food or becomes infested by a disease
organism and most individuals die. The remaining
scattered population then begins a new cycle. The
significance of this for organic gardeners is that a pest
may be much more severe in one year than in another.
It is difficult to determine how well an organic control
is working because of these natural population cycles.



Inability to Tolerate Damage

Many organic control methods rely on maintain-
ing an equilibrium between pest and host. This means
the organic gardener frequently must be willing to
tolerate some damage. How much damage will be
tolerated depends on the individual and also on
whether or not any produce is to be sold. Consumers
frequently complain if even a single insect or fraction
of an insect is found, and lawsuits are not unknown.

Cost of Organically-Grown Vegetables

It would seem, at first, that not using agricultural
chemicals or commercial fertilizers would reduce the
cost of organically grown vegetables. This is seldom
the case. Organic vegetables are often more expensive
than traditionally grown vegetables for several
reasons.

First, organic sources of nutrients or organic pest
control measures are often more expensive than
traditional sources. Second, marketable yields are
frequently less with organic production. Lastly,
organic produce may not store or ship as well as
traditional produce.

Sources of Nutrients and Organic Matter

Organic production frequently relies, at least
partially, on manure, organic material and nutrients
brought in from outside the growing area. These
resources are limited and may restrict the expansion
of organically-grown vegetables. Increased use of
cover crops, green manure crops, crop rotation, etc.
can minimize the effect of the limitations of natural
resources.

Despite the limitations of organic gardening, there
are many proven techniques that will reduce the need
for artificial pesticides and improve soils without
artificial fertilizers. We will now examine some of
these.

ALtarati^e Msans of Bbsc Cfcrtzol
Choose Vegetables and Varieties Wisely

A few vegetables can frequently be grown
without serious damage from insects and diseases.
Examples include beets, carrots, garlic, okra, onions,
radishes and many herbs. Many other vegetables are
susceptible to frequent attack by a number of insect or
disease organisms.



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Grow Resistant Varieties

The University of Tennessee Agricultural Exten-
sion Service factsheet SP277-K, "Disease Resistance
in Recommended Vegetable Varieties for Home
Gardens," lists more than 50 varieties of 21 veg-
etables reported as resistant to one or more diseases.
Many of these varieties have resistance to three or
more diseases. It is important to remember that
resistance is not immunity. A resistant variety will
probably not totally escape a pest, but may be at-
tacked later or bear a fair crop despite being attacked
by the pest. Selecting vegetable varieties resistant to
several pests is well worthwhile if you desire to
reduce the use of plant protective chemicals.

Grow Hybrid Varieties

Hybrid varieties are often more pest resistant than
non-hybrid varieties. This is because hybrids are
crosses of true breeding lines. They are frequently
selected to contain specific pest resistance from both
parent lines. Hybrids also tend to be high-yielding,
earlier-bearing and longer-living than non-hybrid
vegetables, when grown under favorable conditions.
Their increased vigor may permit them to tolerate or
outgrow a minor attack.

Unfortunately, many organic gardeners prefer
non-hybrid varieties. Hybrid varieties do require
favorable growing conditions to reach their full
potential. They also must be grown from purchased
seed, which is expensive because of the labor in-
volved in making the crosses necessary to produce the
seed. Plants grown from seed saved from hybrid
varieties will vary in numerous characteristics rather
than being identical to the parent plants. Saving seed
of hybrid varieties is not recommended.

Despite these disadvantages, hybrid vegetables
are generally a wise choice for gardeners. They have
increased vigor, pest resistance and longevity, and
seem to be equal in taste and nutrition to non-hybrid
varieties. The fruit, in fact, frequently has improved
shelf life and improvements in both appearance and
quality.

Obtain Quality Seed and Transplants

A last consideration in the choice of vegetables
and varieties is the source of the vegetable seed or
transplants. Seed collected locally may carry a wide
range of diseases. It may not be true to type and will
not germinate well unless it is stored properly.

Commercially produced seed is much less likely
to carry diseases, because the seed are produced in
areas having low humidity where diseases and insects



are much less common. Also, obviously diseased or
off-type plants are rogued out before they produce
seed. These seed are also packed and stored properly,
so they will germinate well.

Inspect transplants for the presence of insects,
leaf spots or yellowing and dying leaves. Never
purchase transplants showing signs of insect infesta-
tion or diseases. Young, vigorously growing trans-
plants in individual cells of a cell pack are likely to
grow most vigorously; bare-root and older plants,
least vigorously. Inspect the roots of bare -root plants
and do not buy them if the roots have dried and died.

Use Cultural Controls

A wide range of cultural techniques can be used
to reduce problems of home gardens. Methods of
control vary considerably from one pest to another,
depending on the kind of pest, the vegetable affected
and the interaction of the two. The damage or loss of
one or a few plants is usually considered insignificant.
Control measures are generally aimed at saving the
majority of the crop rather than individual plants.
Most control measures aim at helping plants avoid
contact with pests, as well as eradicating or reducing
the numbers of pests in the area. These methods
include sanitation, proper row spacing, varying
planting dates and seeding rate, crop rotation, planting
on raised beds, adding to soil organic matter, using
mulches, irrigating properly and many others. Most
cultural pest control methods are effective against
more than one type of pest. Gardeners should be
familiar with them and use as many as possible.




Figure 1. Control weeds mechanically while they are
small to reduce the need for herbicides.



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Eliminate Plant Debris

Many insects and diseases survive on plant
residues. Their numbers decrease markedly as the
decay process proceeds. Begin by maintaining the
garden area free from plant debris. Mow or mechani-
cally remove weeds before they produce seed. Indi-
vidual plants of some weeds can produce as many as
a million seed. Remove dead, dying and spent veg-
etable plants from the garden or chop them into pieces
and turn them under as soon as harvest is complete.
This will speed up decay and reduce potential for
disease and insect buildup by removing overwintering
sites of insects and diseases.

Multiple plowings or tillings will not only insure
that all plant residues are worked into the soil where
they will rapidly decay, but will mechanically elimi-
nate many soil insects such as grubworms, cutworms
and wireworms. Working the soil several times is
especially important in gardens that have previously
been in sod for several years, as soil insects are likely
to be present in the sod in large numbers. Weed seeds
will germinate as they are brought to the surface and
be killed as the soil is worked. This can reduce future
weed problems.

Soil free from surface plant debris and organic
mulches will also dry out earlier in the spring so it can
be worked and planted. This is important because
cool-season crops must be planted early if they are to
mature before summer heat halts their growth and
reduces yield and quality.

Increase Soil Organic Matter

Turning plant debris under also increases soil
organic matter. This is discussed in considerable
detail in the "Managing Soils Organically" section of
this publication (p 17). The primary concern here is
the effect of soil organic matter on nematode popula-
tions. Increasing soil organic matter has been widely
reported to reduce nematode populations. Organic
matter apparently enhances the environment for other
organisms that feed on nematodes or directly inhibits
their growth. Plantings of wheat, oats, cereal rye or
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