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Cover Cropping

Note:  Fall seeding is tricky, because we try to leave our peppers and some greens in the ground till the last possible moment.  Mike, the master soil man, discovered that tillilng is not necessary in the black plastic rows, because the soil is perfect for seeding after the plastic is removed.  We used winter rye for our first cover crop in 2003 and, thanks to a warm spell late in October, the grass grew to about 3" tall.

Some legumes can add up to 500 kilograms of nitrogen per 
hectare to the soil,alleviating the need for fertilizer and 
lessening the chance of water pollution(USDA, ARS, Plant 
Genetic Conservation Resources Unit)
1.  Cornell Univ. Extension,  Ecogardening Factsheet #9, Spring 1993
At the end of the growing season you may be ready to rest, but your garden is not. One final effort can make a big difference: cover cropping. Even small gardens will benefit from the use of cover crops, or "green manures". Tilling, weeding, harvesting and foot traffic of most home gardens tends to destroy soil structure. Planting cover crops is an easy way to revitalize the soil, and help soil tilth and subsequent plant growth. Cover crops are planted in vacant space and worked into the soil after they grow instead of being eaten. They provide a number of advantages to the otherwise wasteful use of space during your garden's off-season.

Cover crops help to retain the soil, lessen erosion, and decrease the impact of precipitation on the garden by slowing the runoff of water. They also reduce mineral leaching and compaction, and suppress perennial and winter annual weed growth. The top growth adds organic matter when it is tilled into the garden soil. The cover crop's root system also provides organic matter and opens passageways that help improve air and water movement in the soil.

Success in the growth of cover crops requires proper selection of the kind of cover crop, correct timing of seeding, and good management techniques. There are many traditional cover crops to select from, including annual ryegrass, winter rye, winter wheat, oats, white clover, sweet clover, hairy vetch and buckwheat. Grasses are easier to grow than legumes such as clover because they germinate more quickly and do not require inoculation. Small seeded crops are more difficult to establish than large seeded types such as oats and buckwheat. In poorly drained areas, grasses may be easier to get started. Winter rye and ryegrass grow in a very dense habit and are much more effective at shading out weeds than oats or small seeded legumes. Availability of seed and cost are other important considerations.

If sections of the garden are free during late spring or early summer, clovers, fescue or buckwheat can be planted. If garden space is available in August, barley, annual ryegrass, oats, and clover can be successfully established. The last date when cover crops can be planted in New York will vary with the region, but most New York gardeners should plan to plant cover crops by the end of September. By the beginning of October, only rye and winter wheat can be productively started.

Cover crops such as annual ryegrass, oats, and buckwheat do not overwinter. These crops are the easiest to work with when spring arrives since their tops have died back curing the winter. Perennial ryegrass and winter rye produce a massive amount of top growth in the spring and may be difficult to incorporate. However, perennial grasses are an advantage in wet areas, since the soil will dry more rapidly than a soil with winterkilled crops. If this is the case, before the leaves grow too tall in the spring they should be cut back once with a mower or scythe.

Given all of the above information, how does one choose? For New York conditions, annual ryegrass should be considered first for a garden cover crop. It is a vigorous grower with an extensive root system that occupies the same root zone as the garden plants. Winter rye is another good choice that is best for late planting.

To plant a cover crop, rake the garden area smooth and remove debris or large stones. Broadcast the seed according to the rates on the chart below. Lightly rake again, and water in the cover crop with your hose set at a fine mist.

The following chart provides an overview of the cover crops at a glance. Seed can be purchased at your local garden center or farm store.

 POPULAR AND USEFUL CHOICES OF COVER CROPS

  Vigor of
germina- tion &
establish- ment
Seed cost to plant (1000 sq.ft) Time of planting Over-winter ability Growth amount Ease of
incorpor- ation
Soil structure improve- ment Applic. rate; oz/ 100sq ft Comments
Annual Ryegrass *** * Aug - Sept NO ** **  *** 2 Overall an easy crop to establish
Perennial Ryegrass ** ** Aug-mid Sept *** ** * ** 1 Faster establishment than other perennials. Extensive root system
Winter Rye *** ** Aug - Oct *** *** * ** 3 Can Grow at low pH and at cool temperatures
Oats ***  ** Aug - Sept NO * *** * 4 Requires good soil drainage, but tolerates low pH
Winter Wheat *** ** Aug - Oct *** *** * ** 3 Requires fertile soil; avoid wet or low pH soil
Sweet Clover * * Summer *** *** ** ** 1 Better with high pH than other clovers
White Clover * *(*) Summer *** * *** ** 1 Good for low pH soil, treat with inoculant
Tall Fescue * *** Spring *** * ** ** 1 Persistent, may become weedlike
Buckwheat *** ** Spring NO ** *** * Do not allow to mature,or reseeding will occur

*** = Relatively High

** = Moderate

* = Relatively Low

 Note: Packages of Ryegrass Usually Contain a Mixture of Annual & Perennial Types


 

 

2.  Cover Cropping, USDA Extension  
WINTER RYE (Common)(968): Secale cereale Hardiest winter
cover crop - to prevent soil erosion and add organic matter. If rye grain or straw is
desired, sow in fall for mid-summer harvest. For green manure, sow anytime spring through
mid-fall at 4-6 lbs. per 1000 sq. ft. (2 bushels per acre). 
BUCKWHEAT (Common)(966): Fagopyrum esculentum
 For summer green manure - sow in late May through July and till in
about a month later when flowering has begun. For grain harvest, sow 3 mo. before fall
frost; harvest after killing frost. Planting rate: 2-3 lbs. per 1000 sq. ft. (60 lbs. per
acre), one-fifth less when planting for grain harvest. 
OATS (Ogle)(971): Avena sativa
Quick growing green manure crop - sow anytime of year. For winter cover sow by early
September here, slightly later further south; the heavy stubble will prevent erosion and
oats will not re-grow in the spring like winter rye. Sow at 3-4 lbs./1000 sq. ft., or
about 3 bu./acre. Sow in early spring for grain. 

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Minimum Chemical Gardening Author: Diane Relf, Extension
Specialist, Environmental Horticulture, Virginia Tech Publication Number 426-366,
August 1996 
Introduction Home gardeners often use more pesticides per square
foot in their gardens than farmers do in the fields, thinking that if a little is good,
more will be better. This is a serious mistake, and a misuse of pesticides. Over-use of
pesticides has a number of adverse effects: it makes your food less safe to eat,
especially if there are residues at harvest time; it makes handling the plants more
dangerous; beneficial insects, earthworms, birds, even pets may be harmed or killed along
with the "bad guys;" each time the gardener sprays, she or he is exposed to the
dangers of inhalation or absorption of the toxin; pesticides used near water may
contaminate the water supply; continuous use of certain pesticides may induce resistance
in the pests, thus requiring the gardener to switch to more toxic substances; some
pesticides do not break down easily and can remain in the environment for years. The
growing public concern over the use and misuse of pesticides has led increasing numbers of
home gardeners to seek means of "natural" pest control. Although some people do
not have the time or knowledge to practice all the available alternative methods for
controlling pests, there are many cultural practices which will help reduce losses.
Because the gardener does not have to live up to perfect market standards, pesticide use
may be reduced to a minimum with a little research and effort. And, if the choice is
between minor insect damage and a possible pesticide residue, consider accepting the
visible blemish you can cut out.

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Soil Preparation Maintain a slightly acid soil (around pH 6.5). If in doubt,
have an analysis done of your soil through your local Extension Office, by a private lab, or with
a soil test kit. The appropriate pH allows vegetable plants to have access to all the
necessary soil nutrients and provides a suitable environment for earthworms and
microorganisms. Build a biologically active, healthy soil through regular addition of
organic matter. Compost and manure can be incorporated into the soil and various mulches
such as leaves and grass clippings can be applied on the surface. Organic matter is
essential for providing good soil structure, moisture infiltration and retention, and
gradual release of plant nutrients. Regular addition of organic matter to garden soil can
totally eliminate the need for chemical fertilizers, although moderate use of chemical
fertilizers is helpful during a transition period until sufficient soil organic matter
content has been obtained. Addition of organic matter has also been shown to be effective
in suppressing many soil-borne plant pathogens by encouraging beneficial microorganisms.
By improving the general conditions for plant growth (i.e., moisture retention, improved
soil aeration, and soil fertility), the addition of organic matter helps reduce various
stresses on plants which make them susceptible to pathogens and insect pests. 
Grow winter annual cover crops to provide additional organic matter without the
effort of hauling, fix free nitrogen from the air, reduce loss of soluble plant growth
nutrients through leaching, and provide a bright patch of greenery during the winter
months. A mixture of rye grain and hairy vetch makes a good winter annual cover crop if
seeded at a rate of 2 lbs rye and 1 lb of hairy vetch per 1,000 sq ft of garden. After the
summer garden crops have been harvested, stalks and vines should be removed and composted,
and the garden lightly tilled to prepare a seedbed. The cover crop seed can be broadcast
and raked lightly with a leaf rake to cover the seed. If possible, irrigate after planting
and then every 4-7 days until the crop has emerged. Be sure to inoculate the hairy vetch
seed with Rhizobium bacteria to enable the vetch to fix nitrogen. Pour the seed into a
bucket with a small amount of vetch inoculant (available in garden stores) and add enough
water to dampen the seed. Mix thoroughly and plant. Winter annual cover crops can be
planted as late as Oct. 15-25. In the spring, mow the cover crop with a lawn mower set at
the highest setting prior to tilling. Till in the cover crop at least two weeks prior to
planting garden crops. During spring and summer, as areas of the garden are harvested,
plant a summer cover crop of buckwheat. This crop grows quickly, maturing in less than
thirty days. Let the buckwheat flower, but incorporate prior to seed set. When diseased
plant material is added to compost to be used on your garden, delay using the compost
until all has decayed beyond recognition. Compost piles should be hot (140 degrees F.) to
kill disease organisms, insect eggs, and weed seeds. Till in the fall to expose those
stages of pests which live near the surface of the soil to natural enemies and weather,
and to destroy insects in crop residues. Plant winter annual cover crops whenever
possible. If you do not till in the fall, do so early enough in the spring to give
remaining vegetation time to degrade before planting time.

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Plant Selection
 Plant crops that are suited to the soil and climate. If you do plant vegetables or fruits that are not normally grown in 
your area, do your best to provide necessary conditions. For example, watermelon prefers a light, warm, well-drained soil;
don't try to plant in heavy clay without first adding copious amounts of compost or other
soil-lightening material, and allow the soil to warm up before seeding or setting plants
out. Use disease-free, certified seed, if available. Select disease-resistant vegetable
and fruit varieties. Select plants that are sturdy and have well-developed root systems.
Diseases and insects in young seedlings may start in greenhouses or plant beds and cause
heavy losses in the garden. Buy plants from a reputable grower who can assure you that
they are disease- and insect-free, or grow your own from seed.

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Cultural Practices 

The most effective and most important of all practices is to observe what is going on
in the garden! Many serious disease or insect problems can be halted or slowed down early
by the gardener who knows what to look for and regularly visits the garden for the purpose
of trouble-shooting. 

Water in the morning so that plants have time to dry before the cool evening. Drip 
irrigation prevents foliage from getting wet at all when watering. For plants susceptible
to fungus infections, such as late blight on tomatoes, leave extra space between them to 
allow good air flow; orient rows so that prevailing winds will help foliage dry quickly
after a rain or watering. While this may reduce the number of plants per square foot, 
you may still get higher yields because of reduced disease problems.

Use interplantings as opposed to solid plantings of a crop. This can slow the spread of 
diseases and pests, giving you more time to deal with them. Thin young plants to a proper 
stand. Overcrowding causes weak growth and subsequent insect and disease problems. 
Keep down weeds and grass.
They often harbor pests and compete for nutrients and water. 

Leaf mulches are extremely effective for weed control. Use a mulch to reduce soil splash,
which brings soil-borne diseases into contact with lower leaves. 
Rotate your garden plot, if you can. Do not grow the same kind of produce in the same 
place each year.  Use related crops in one site only once every three or four years. Some
related crops are as follows: (a) chives, garlic, leeks, onions, shallots; (b) beets,
Swiss chard, spinach;(c) cabbage, cauliflower, kale, collards, Brussels sprouts, broccoli,
kohlrabi, turnips, rutabagas, Chinese cabbage, mustard; (d) peas, broad beans, snap beans,
lima beans; (e) carrots, parsley, celery, celeriac, parsnips; (f) potatoes, eggplant,
tomatoes, peppers; (g) pumpkins, squash, watermelons, cucumbers, muskmelons; and (h)endive,
salsify, lettuce.
Avoid injury to vegetable plants. Cuts, bruises, cracks and
insect damage are often the site for infection by disease-causing organisms. In cases
where fruits are difficult to remove (such as cucumbers and watermelons), cut them off
instead of pulling them off the plant. If you cultivate your garden, avoid cutting into
the plant roots. Stay out of the garden when the plants are wet with rain or dew to
prevent spreading diseases. 

Do not use tobacco products such as cigarettes or cigars when working in the garden. 
Tomatoes, pepper, and eggplant are susceptible to a mosaic virus disease common in tobacco
and may be spread by your hands.
Remove infected leaves from diseased plants as soon as you observe them. Dispose of
severely diseased plants before they contaminate others. 
Clean up crop refuse as soon as you are finished harvesting if possible. Keep old sacks,
baskets, decaying vegetables, and other rubbish which may harbor insects and diseases out of the garden.
Staking plants or planting them in wire cages prevents the fruit from coming in contact 
with the soil. This also helps prevent fruit rots. Caging helps reduce sun scald often 
seen in staked tomatoes, since caged plants do not require as much pruning, leaving a 
heavier foliage cover. Place boards or a light, open mulch such as straw beneath melons
lying on the ground to prevent rotting. 
Time plantings in such a way that the majority of your crop will avoid the peak of insect
infestations. For example, plant squash as early as possible to avoid borers, which lay
eggs in July. Keep a record of the dates insect problems occur. Also, by planting
warm-weather crops after the soil has warmed, you will avoid problems with seed and root
rots; growth will be more vigorous, as well. 
Inspect plants for egg clusters, bean beetles, and
caterpillars and other insects as often as possible. Hand-pick as many as you can.
Knocking insects and egg clusters into a coffee can with a small amount of water in it and
then pouring boiling water over them is a way to kill insects if you don't like squashing
them. Kerosene is often recommended, but there is a disposal problem once you have
finished; besides, water is cheaper.

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Alternatives
Take advantage of the biological control already taking place in your garden by
encouraging natural predators, such as preying mantises, ladybugs, lacewings, ground
beetles, and others. Purchased natural predators are often ineffective, however, since
they tend not to remain in the place where they are put. Research the likes and dislikes
of these helpers as to foods, habitat, etc. Provide these conditions where possible.

Learn to recognize the eggs and larvae of the beneficial insects and avoid harming them.

For example, the tomato hornworm is often seen with a number of white egg cases, a little
larger than a grain of rice, on its back. These were laid by a parasitic wasp. The
hornworm will die and more wasps will emerge. Obviously, it is to your advantage to leave
the worm in the garden, moving it to another place if it is doing a lot of damage.


Spiders, toads, and dragonflies are beneficial and should not be a source of fright to the
gardener; in most cases they are harmless to people. Use various insect traps to reduce
the insect population levels. Upturned flower pots, bamboo lengths, boards, etc. will trap
earwigs and sowbugs; collect them every morning and feed to pet frogs, toads, turtles, and
fish, or destroy with boiling water. Slugs can also be caught by these means and can be
killed. 

Indoors, white flies can be caught with sticky yellow traps, made with boards
painted yellow and lightly coated with oil or grease. There are also commercial sticky
traps available through some catalogs. 

Although several Japanese beetle traps are on the market which are effective at attracting
beetles, use of these traps has not been shown to be effective in preventing Japanese 
beetle injury to garden plants, since the traps attract beetles from a wide area.
Similarly, light traps and electric "zapper" traps operated at night can capture or kill
a large number of insects; however, these devices are indiscriminant -- they kill
beneficial as well as pest insects -- and will not aid in control of insect pests
 
Natural pesticidal products are available as an alternative to synthetic chemical
formulations. Some of the botanical pesticides are fairly toxic to fish and other
cold-blooded creatures and should be treated with care. Safety clothing should be worn
when spraying these even though their toxicity is low to warm-blooded animals. The
botanical insecticides break down readily in soil and are not stored in plant or animal
tissue. Often their effects are not as long-lasting as those of synthetic pesticides.
Apply insecticides locally, to take care of a specific pest problem, instead of blanketing
the entire garden. 

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INSECTICIDE USE AGAINST 
Pyrethrum: Pickleworms, aphids,
leafhoppers, spider mites, harlequin bugs, cabbageworms, Mexican bean beetles, flea
beetles, flies, squash bugs 
Rotenone: Colorado potato beetle,
Mexican bean beetle, Japanese beetle, flea beetles, cucumber beetles, spittlebugs, aphids,
potato beetles, mites, carpenter ants, cabbage worms, loopers, fleas 
Ryania: Codling moths, corn earworm, Oriental fruit moth, potato aphids, onion, thrips, 

corn earworms, 
Sabadilla:
Armyworms, Harlequin bugs, stink bugs, cucumber beetles, leafhoppers, cabbage loopers,
blister beetles Some of these products may be very difficult to find. In addition to the
botanical insecticides, some biological products can help in the battle against insects.
Bacillus thuringiensis is an effective product commonly used against moth larvae.
B.t., as it is known, is a bacteria that produces a toxin quite lethal to caterpillars,
but nontoxic to beneficial insects and mammals. B.t. is most effective on young larvae.
Presently, there is research underway to develop strains that work against other types of
insect larvae. Another biocontrol product which is just becoming available to gardeners is
grasshopper spore; it is not proven for small-scale use, but may help gardeners reduce
damage by grasshoppers.
Commercial insecticidal soap, a special
formulation of fatty acids, has been proven effective against aphids, leafhoppers,
mealybugs, mites, pear psylla, thrips, and whiteflies.
Homemade soap sprays
also work to some extent: use three tablespoons of soap flakes (not detergent) per gallon
of water and spray on plants till dripping. 
Repellent sprays,
such as garlic sprays and bug sprays (made from a puree of bugs), have been found useful
by some gardeners, but their effectiveness is questionable. Some researchers believe that
bug sprays may work if a disease is present in the insect, which is spread through the
spray to other insects. 
Various materials can be used to physically block or
repel insects and keep them from damaging the plants. Place wood ash,
cardboard tubes, or orange juice cans around seedlings to keep cutworms away from plant
stems. Use paper bags over ears of corn to keep birds and insects out; do not cover until
pollination is complete. Net-covered cages over young seedlings will help prevent insect,
bird, and rabbit damage. Where slugs are a problem, use methods described under trapping
above, and try to create drier conditions. Heavy mulches may sometimes encourage slugs.
Spread crushed eggshells or hydrated lime around affected plants. 
Enlist the aid of birds in your garden. In rural areas, chickens, guineas, and other 
domestic fowl are released in unused areas of the garden to eat grubs and insects. Wild 
birds will also help, but aren't as controllable. If you encourage wild birds you will 
have to protect ripening fruit (and even some vegetables); use bird netting or scare 
devices (aluminum pans banging in the breeze are fairly effective). Overall, birds do 
more good than harm. Consider planting shrubs and trees with fruits that attract them.