Natural Pest Control

After all the effort of growing young seedlings and watching fruit ripen, there is nothing more disheartening than seeing them attacked and eaten by garden pests.

Most garden pests can be controlled by natural means, eliminating the need for pesticides or chemical use. This could be very important for the health of the people eating the food.

There is some evidence that chemical pesticides are very harmful for human health. One of these indicators is the over 70,000 accidental exposures to these chemicals in the USA alone.

Another is a few landmark papers that relate pesticide use to a variety of cancers. Is this evidence conclusive? The petro chemical industry would say no. But when the risk is your own family’s health, is it worth it?

Using chemical pesticides in hydroponics is far more dangerous than using these chemicals on soil based crops. Their data about decay often requires soil microbes to be present, also a given temperature and moisture level.

In hydroponics we have no, or at least much reduced, soil and soil microbes so we cannot rely on their claims of decay and elimination of the pesticide even under the best of environmental conditions. Where a soil based crop may reduce and decay the pesticide, our crops could accumulate it.

Early commercial hydroponic crops used chemical pesticides to control insects, often in greenhouse conditions. A Dutch company called Koppert started to market beneficial insect control in greenhouses and changed this practice.

The company owner, Jan Koppert, developed an allergy to many chemical pesticides. He decided to experiment with controlling spider mites with a predatory mite. The company is now the international leader in integrated pest management.

Natural Pests for Control

Koppert has an established routine for controlling insects in the greenhouse. They even sell bumble bees to ensure that the crops get pollinated. These small decorative houses are bought by commercial growers and placed throughout the large greenhouses. Before the bumble bees, the growers carefully pollinated their plants by placing a vibrator on each plant to make the top pollen fall on the bottom fruit. This time consuming process is now replaced by the bumble bees, who do not damage the plants and appear to never miss a blossom.

Koppert’s control of other insects includes bringing beneficial insects into the greenhouse to prey on the bad guys who eat our crops. These include mites, white fly and aphids. While koppert has several types of controls, one of the most popular is strips of paper clipped to tomato stalks that have wasp eggs on them. A grower carefully clips these papers on plants in strategic distances and on a timetable to keep the wasps hatching. The wasps are an effective control against white fly. Similar strategies are used for aphids and other insects.

In simplified hydroponics, our gardens are usually outdoors where we cannot count on our beneficial insects staying in place. So we rely on two basic methods of control: prevention and then sprays made of household materials.

Prevention

In commercial gardens, a yellow sticky card is used as a trap for white fly and some other flying insects. The yellow attracts the insect looking for blossoms, and then the sticky substance traps them.

Yellow Cards

In simplified gardens we construct a large yellow sticky card, usually at least one square foot and often even larger. This wood and plastic construction is then smeared with motor oil to catch the insects. The cards are placed throughout the garden, especially on the edges.

Blue Cards

We also make a similar card of blue plastic to attack other insects, such as thrips. Thrips are very small black insects that fly into your garden. If you have an infected area, they can be found by placing a white piece of paper under a plant and shaking it to remove insects. Tiny black spots are probably thrips. Blue cards placed in the garden should control them.

Water Bags

There is one other control which is very effective for flying insects. Clear plastic bags filled with water and hung around the garden repel insects. The compound eye of most insects gets confused by the multiple reflections of the plastic and they fly away, probably to someone else’s garden that does not have plastic water filled bags.

Sticky Tape

How aphids usually get into your garden is that ants bring them into the garden and deposit them on the leaves of the plant. The ants will later come back and milk the aphids for their honeydew. So the aphids basically function as the ants’ cows.

Controlling ants in your garden controls most aphids, so protecting the growers from the ants controls the aphids. Wrap any legs of table growers or grower supports with a sticky tape. Tanglefoot is a commercial product.

In some seasons, some types of aphids can also fly. For that time, repelling plants and sprays can help.

Magnetic Tape

One of the more difficult pests to control is seed eating birds that invade the garden and eat seeds or seedlings.

The most effective control we have found is taking an old magnetic tape like that used in cassette tapes and stringing the brown tape liberally around the growers. This may require building a superstructure of some kind to hang the tape. The tape strings down like confetti from above and the birds are repelled by the flying and the reflective surfaces.

Repelling Plants

Several of the aromatic plants are effective at repelling insects. They are usually not very effective on their own, because the range of protection depends upon things like winds. But in combination with the sticky cards, a garden starts to be more pest-free.

Basil is the number one favorite garden plant to place on edges and corners to repel insects. This is also a favorite herb for foods such as pesto and basil tea. Even small gardens should have a few plants.

There are several medicinal or culinary plants that also repel insects, such as caraway, yarrow, fennel, mint and cilantro. A few of these can be planted in the garden.

Garlic and onion repel aphids, so these can be planted around the plants that attract aphids, such as tomato and bell pepper.

Prevention Sprays

A basic method of garden protection is to spray the garden once a week with a prevention spray. We use several in gardens but the best appears to be a garlic spray.

Garlic Spray

Garlic spray is used with a spray bottle, and applied over the leaves of the plants. The residue usually lasts about a week, but if the plants are outside and exposed to heavy rainfall the garlic spray could be reapplied.

Garlic spray is made by grinding or mashing about 30 cloves of garlic. These are placed in a glass container and covered with boiling water. The container is then covered and kept for about five days. This makes the garlic concentrate.

A spray is made by adding three tablespoons of the garlic mix per half liter of water (pint). This is then sprayed on the garden plants.

There are several other sprays made to prevent insects, but garlic seems to be the most effective, and it can be easily grown in the garden.

What Happens When You Have Insects?

There are methods to control insects once they invade the garden.

Daily Inspection

Some flying moths, especially the white cabbage moth, will come into the garden and lay eggs that take about five days to hatch. Once they hatch they will turn into a worm that will invade the roots of the plant.

There is a five day period where the eggs can be found and removed. They are usually easily spotted, and then scooped out of the growing media. A garden owner should always be inspecting the surface of the media for eggs of insects.

Daily inspection will also help to discover insects on your plants as they first arrive. At the first arrival, when there are just a few, the insects can usually be controlled with a soap spray.

Soap Spray For Killing Insects

A soap spray will often kill most soft bodied insects such as aphids and white fly larvae. It can kill adults too if they receive a full direct spray.

We make a soap spray from a dishwashing soap, such as Sunlight, Dr. Bonner’s Soap, or Castille hand soap. A tablespoon of soap concentrate is mixed with a liter (two cups) of water and sprayed on the insects. Spray undersides of infected leaves where the eggs or larvae might be hiding.

Recipe For Castille Soap

78 ounces olive oil

6 ounces coconut oil

6 ounces palm oil

24 ounces cold water

12 ounces lye crystals

Dissolve the lye in cold water. Do not use an aluminum container. Stir until dissolved and let cool.

Mix and warm the three oils. Then slowly pour the lye mixture into the oils.

A honey-like texture is formed in about 10 or 20 minutes when the lye is incorporated into the oils.

Scents and essential oils can be added when the soap is mixed.

When the soap is close to being ready to pour, it will usually start looking duller on top and form a bit of a fine ring around the edges of the bowl or pan it’s in. It should have a satin finish and smooth texture... not be terribly grainy.

Pour this mixture into a wooden box that has been soaked in water and lined with a clean cotton cloth dipped in water and wrung nearly dry. Place in a protecting pan. Cover with a board or cardboard then with a rug or blanket to retain the heat while it is texturing out. Let it remain undisturbed for 24 hours - then cut and lift from mold.

The soap spray is not so effective when the plant is very infested with insects. That is because it is so very hard to get them all with the spray. A heavily infested plants should be removed from the garden, put into water for a few minutes and then left outside to see if it recovers. Most plants will still be infested and have to be destroyed.

Killing Aphids

Aphids, once on the plant, are very difficult to get rid of. A female aphid can have 50 daughters asexually, and those can also reproduce asexually. Without control, aphids often win the battle for the garden.

In simplified hydroponics we make a spray of hot pepper with seeds, ground and added to water with a soap. The spray is applied three times a day for three days, then two times a day for the next five days.

Powdery Mildew, Fungus Infections

The best spray we have found to control these types of diseases is a spray of half milk, half water. It seems that milk has natural disease fighters that can kill mold and mildew. This can be cow milk, or goat milk, but should be diluted. Pasteurized milk may not be as effective.

There are several more specific sprays that can be made to control specific insects and diseases. The Hydroponics and Microfarms CDROM lists 28 different sprays with recipes.

Other Sprays

Almost all sprays used to repel insects are made in a manner similar to garlic spray. A strong tea is made from the substance and then used as a spray in the garden. Extra tea is kept in clearly marked bottles.

Tobacco Spray

The stems of tobacco plants are mashed, placed in jar with hot water for five days. Use three tablespoons per half liter of water. Especially good for white fly.

Hot Pepper Spray

The peppers are mashed and placed in a container of hot water for five days. The spray is made from three tablespoons of hot pepper mash per half liter of water.

Worm Castings Tea

The worm castings used from the worm farm for a hydroponic nutrient can be used as an insect spray when sprayed onto plants. The tea is made with worm castings soaked in water. The tea is strained through cheesecloth to remove particles that can clog your sprayer.

Oil Spray

An oil spray will kill young larvae and eggs, but it must be sprayed directly on them. It can be made of any vegetable oil and water.

Caution:

Many of the insect sprays are also poisonous to humans. Of all the sprays, garlic will probably be the safest, but treat all as poisons and keep out of the reach of children.

Natural Predators

Many insects and animals eat insects, and some can be encouraged to make their homes in or near your garden. If you can obtain a balance, they will be able to keep the insects in control.

Ladybugs

Ladybugs feed on aphids and will patrol the garden to find them. Lady bugs make their homes in older rotting wood logs. If a lady bug home can be provided in the garden, it will help keep aphids down.

Predator Wasps

Encarsia formosa is a wasp in the US and Canada that is a natural predator of white fly. The larvae can be purchased and then released into your hydroponic garden.

The wasp controls the white fly by laying its eggs in the white fly larvae. This keeps the white fly population in check, and the fly and wasp should remain in balance, if both are in the garden.

Bats

Bats eat at night, and they will eat several thousand insects. They are especially effective in keeping moths out of the garden. A bat house can be built and placed near the garden. Bat guano is also an organic hydroponic nutrient.

Lizards

There are lizards that feed on insects. They can be encouraged to make a home in the garden and will patrol the beds for insects.

Spiders

The common house spider eats flying insects and will be especially effective against house flies. They should be allowed to make their homes among the garden growers.

Koppert Company website http:://www.koppert.com. Natural Sprays Hydroponics and Microfarm CDROM, www.carbon.org