Every gardener faces some problems with the garden at one time or another. Environmental problems, insects and diseases can create havoc among the plants and often leave the grower stumped.
The best way gardeners have prevented problems has been to carefully examine the garden at least once a week. First a gardener looks at the entire space. Do the plants look healthy and vigorous? Is their color normal and bright? Then the grower examines a few plants closeup. Do they look healthy? Have they grown since the last examination? Do the leaves or any other plant parts show signs of nutrient problems? Taking a photographer’s x 4 or x 8 loupe, available at camera stores, the cultivator looks at the leaves of several plants. He asks, "Are there any abnormalities? Any insects or eggs on the undersides?"
The most common problems with plants are not pests. They are over watering, under watering and over-fertilization.
When the medium is waterlogged the roots cannot obtain enough oxygen. At the same time, anaerobic bacteria, which are active in oxygen free environments, attack the roots and produce ammonia. Plant leaves may curl under from lack of oxygen. Waterlogged medium is not usually a problem for hydroponic gardeners but may occur in a some planting mixes. One solution is to water the plant less.
Roots have a harder time drawing water as the medium dries. During the light hours, the need for water is especially acute. If the roots have no moisture; first the bottom leaves and then the entire plant starts to wilt. Water must be added before the leaves die, which can be only a matter of hours. The old myth that water stressing the plant increases potency is not relevant to indoor cultivation.
Slight chronic over fertilizing can cause the leaves to curl either upward or underneath. Heavy over fertilizing can cause the plant to wilt in a matter of minutes. When the soil medium has a higher concentration of salts (nutrients) than the plant, it draws water from the plant. The only solution growers reported to this problem is to get rid of the excess nutrient by rinsing it out. Once the plant starts to wilt, a few minutes may mean life or death.
THE PESTS
The best way to deal with pests is to prevent them from infecting the garden. A smart gardener never goes to the indoor garden after being in the yard or around outdoor plants. S/he may inadvertently carry in pests. While they are kept in check naturally outdoors, they have a field day indoors in a much less hostile environment. Healthy plants should be kept away from infected plants and should not be handled after handling infected ones. The pests most likely to infect an indoor garden are mites, white flies and aphids.
MITES
Mites are not insects but arachnids, related to spiders. They are very small and look like small brown, red or black dots on the undersides of leaves. A blemish can be seen on the top side of the leaf where they have been sucking. The infection may not be noticed until after there are 10-50 of these on a leaf. Using a magnifier they will be noticed walking around on their eight legs when they are not sucking the plant dry. Mites thrive in a dry environment. High humidity and low temperatures slow them down.
There are two major problems with mites. First, they breed very quickly every 8-14 days and they like large families. Secondly, they are hard to control. Before budding a soap dip or the homemade bug killer will knock down the population. Then pyrethrum and soap sprays will keep it low. Growers realize that the idea is not to expect to eliminate them, but to keep the population down so that it does little damage to the crop. Once established; mite predators, which are other mites which feed on their cousins, keep the population totally under control it may take several introductions to get them started There are several different species of predator mites, each does best at a slightly different temperature range. Some growers introduce mixed populations, others just one species.
APHIDS
Aphids are oval looking insects about 1/16 of an inch long that come in a rainbow of colors including white, green, red brown and black. They are soft skinned and are often farmed by ants which squeeze them for their "honeydew" which is a sugar concentrate. Aphids suck on plants looking for protein. The excess sugars are exuded onto plants and these areas become hot spots for fungal and other infections. Aphids breed very quickly, and like warm, dry climates. They are very susceptible to pyrethrum and dry up from soap sprays. The home made spray a grower developed works wonders against them.
WHITEFLIES
Whiteflies look just like a housefly except they are only about 1/5-1/10 the size and are all white. They fly around the plants when they are disturbed. Whiteflies are susceptible to pyrethrum, but the best control is with Trichogamma wasps, which get them under control in just a few weeks.
Trichogamma wasps are about ¼ the size of a white fly and are harmless to humans and pests but not to whiteflies. They parasitize the larger whitefly egg, laying their egg inside it. Once released they fly around and live in the garden but are rarely seen. Until wasps are introduced the aphid population is kept in check using pyrethrum sprays. The wasps are susceptible to sprays so growers do not spray for several days before release.
Pesticides
In the past few years there have been giant strides made in the development of safe pesticides for indoor use. A few companies produce safe insecticides in aerosol form which release a measured spray periodically. The aerosols use environmentally safe propellants.
Concerned growers never use pesticides which are recommended only for ornamentals. What this really means is that it is NOT RECOMMENDED for food crops. The best pesticides to use are natural ones which have a short life, or simple non-toxic ones which often act by physical or simple chemical rather than biological means. Some growers have found a few safe pesticides which are available at plant and grow stores. They said they helped to eliminate pest problems.
- Pyrethrum based insecticides and miticides. Pyrethrum is a broad spectrum insecticide produced by the pyrethrum, a flower closely related to the chrysanthemum. It is toxic to cold-blooded animals including fish. Insects and mites are all susceptible. It seems to have no effects on warm-blooded animals and once it is used it quickly loses its activity. Pyrethrum based insecticides usually state that they can be safely used up to the time of harvest.
- Soap based insecticides and miticides use the ingredients in soap to physically dry out and incapacitate the pests. These sprays usually come in trigger type bottles. After using, the soap residue dries. Then it can be rinsed off the plant, Liquid soaps found in the supermarket such as Ivorytm and Dr. Bronnerstm Peppermint or Eucalyptus can also be used. They are usually diluted at the rate of ½ teaspoon per quart of water.
- Biological controls. Some pests have natural predators which keep them under control. Predatory mites keep mites under control. Whiteflies are easily controlled using the trichogamma wasp, which lays its egg in the fly egg. These wasps are very tiny, do not bite or sting and are non-social, they do not have nests. Once they are released, they are hard to find because they are so small. But they do a great job and are the best control for white flies.
- A grower’s homemade spray which he said works well has the following recipe.
- 1 quart water
- 3 ounces strong onion, peeled
- 2 ounces fresh garlic
- 2 tobacco cigarettes (remove paper)
- 1/8 teaspoon dish washing detergent
- 4 ounces denatured alcohol
- 2 tablespoons buttermilk
- 1 Teaspoon Dr. Bronners Peppermint soap
- 3 ounces strong onion, peeled
- 1 quart water