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Killing Nematodes Naturally E-mail
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Monday, 02 July 2007
Killing Nematodes Naturally


Countryside & Small Stock Journal

By Johnny Papaya Burns

Nematodes are the unseen menace (eelworm) in elephants, whales, gnats and even minnows; all have nematodes in their bodies. Nematodes can thrive in such varied environments from the most arid desert to farmlands to the icy saltiness of arctic seas. But they thrive in such ideal conditions in Florida.

Nematodes (or roundworms) are so small that 8,000 can lie on one single thumbnail without overlapping. But some up to 30 feet long have been found in whales.

The nematodes, which bother us gardeners the most, live off plant juices and animal fluids. Some of them (not enough) are cannibalistic. More than 30 species attack man, the hookworms being the most familiar ones. Under a microscope, the very small nematodes are seen as a wormlike almost transparent creature devoid of eyes, ears, nose, or brain. It has no blood or skeleton and is responsible for millions of dollars in crop losses each year. They are very destructive when they get around the roots of your tomatoes, sucking the juices from your plant until it withers and dies.

Varieties of nematodes:

1. Ectoparasites live in the soil but outside the plant.

2. Endoparasites live partially or entirely inside the plant.

Both types insert a needle-like spear called a stylet into the plant to extract juices. The Ectoparasites usually have a longer stylet.

Nematodes usually spends their lifetime in a small area moving only a few inches to a foot in a year, but they travel and spread, and we unwittingly help to spread them. They are carried great distances on the dirt of shoes, in the soil of potted plants, even in running water.

Some experts say, for every plant on Earth, there is at least one nematode that will attack it. There are 10,000 species of nematodes known to man. Farmers or at least most of them are fighting an uphill battle trying to develop nematode resistant plants only to find that a new species often pops up to feed on these supposedly resistant crops. These species were probably there all the time just waiting for a plant of their liking to come along for them to attack.

Dr. Gerald W. Thorne, plant pathologist at the University of Wisconsin writes: "Because of nematodes, we have not realized the fullest possible production from our gardens and farms. Our successful control of them would help the world's ever increasing need for food."

On hot summer days nematode infected succulent plants tend to wilt more rapidly than healthy plants but usually recover when the temperatures become cooler. Yellowing of foliage and "dieback" of branches or shoots may also be a common occurrence with nematode infestation.

Nematode control without poison

When quantities of organic fertilizers, compost, mulch, seaweed or foliar nutritional sprays are used, the humus will destroy the nematodes.

The man most responsible for this important research is Dr. C.L. Dudington, senior lecturer in the field of botany at the Regan Street Polytechnic in London, England. Back in 1951 Dr. Dudington performed his first experiments, conducted in flowerpots on a roof in Central London to learn the value of a combination of organic materials and fungus cultures. Later he performed field tests with farm crops, mostly cereals and potatoes. All his experiments clearly showed that nematodes can be controlled by building up concentrations of beneficial fungi and organic matter in the soil around the plants.

Beneficial fungi

The beneficial fungi are closely related to the blue mold penicillium but are invisible to the naked eye. They achieve their results by virtually eating nematodes alive.

Botanists refer to them as precious fungi and also as "fungi imperfecta" (they have no sex life). There have been 48 different species of such nematode eaters isolated. They can be grown in the laboratory artificially with considerable ease if proper facilities are available.

In their natural state, these fungi grow in decomposing vegetable matter.(compost) and manure, especially rabbit and chicken.

The fungi are quite widespread, easily isolated, harmless to crops, animals and humans, but to nematodes they are killers.

How the fungi do their work

The fungi destroy nematodes in a number of ways. In some cases the fine threads of the fungus have branches which form loops and these loops in turn form three-dimensional networks, something like crumpled wire netting. This network secretes a sticky fluid when they come into contact with the nematodes and the nematode is caught as effectively as a fly in a spider web. After the fungus catches the nematode it then sends branches into its body or grows into it and simply absorbs its tissue.

Another way in which fungus traps nematodes is by sticky branches which reproduce rapidly and form little circular loops in which the nematode is trapped.

The third way the fungi works consists of sticky knots at the end of stalks. These knots hold the nematode and form a structure inside which spreads out and destroys it.

The fourth way is by the formation of a constricting ring of three cells on a stalk. The nematode gets its "nose in a noose" or ring accidentally; the cell swells and the ring closes.

Benefits from compost and mulch

The advantages of controlling nematodes by fungi and organic matter are many. There are lots of chemical killers of nematodes but the poisons are not so selective, they do not just kill the destructive nematode but also beneficial soil bacteria and the helpful earthworm, the gardener's best friend. If you use poisons you could end up with dead soil, and natural soil is teeming with millions of beneficial creatures in balance. Also, these chemical killers are quite expensive to purchase and they do not feed your soil or your plants as good compost and mulches do. Compost and mulches are free for the asking, and a little work. When the mulches decay it feeds the earthworms and beneficial bacteria. The earthworm's droppings are the world's best fertilizer. Charles Darwin called the earthworm the intestines of the soil. The earthworm also aerates soil. Where you see lots of earthworms you know your soil is alive, rich and healthy.

To be truly effective chemical killers must be thoroughly mixed into the top nine inches of soil which is something like 1,000 tons per acre, so if you think of compost as work, think of that load.

Mulch against the root knot nematode

A report came from the University of Florida Agricultural Experiment Station over 20 years ago revealing the value of humus against nematodes. Some plants found to be susceptible to nematode injury that benefited from mulching were okra, tomatoes, peppers, eggplant, squash, cantaloupes, watermelons, beans, celery and lettuce. Vegetables (plant) matter decays rapidly, especially during warm weather. Things like grass clippings, weeds, and leaves are all excellent mulch, as well as kitchen scraps such as coffee grounds, vegetable peelings, eggshells and even sawdust adds organic matter. Fungus develops in this rotting vegetable matter and has been seen by a number of investigators to trap nematodes and destroy them.

Dr. Dudington took small plots which previous tests had shown to contain suitable fungi and they were artificially infested with nematodes by adding infested soil.

Half the plots were then treated by digging in chopped cabbage leaves while the control plots were left untreated, i.e. no cabbage leaves.

The results were, in Dr. Dudington's words, "quite dramatic." A perfectly healthy crop was harvested in the plots where cabbage leaf mulch or compost was used, but the control plots had severe nematode damage to the plants grown there. The plots were sampled by taking plants at the seedling stage and counting the nematodes in the roots while soil samples from the plots were also tested for fungus activity. These samplings showed far fewer nematodes in the treated (cabbage leaves) roots, where the activity of fungus was correspondingly greater.

But perhaps the most decisive of all the trials was held in Lincolnshire with farmyard manure. The land tested was heavily infested by potato root nematode and had been officially ruled as unfit for growing potatoes. The plot was treated with manure and fungus and it produced an excellent crop of potatoes while the untreated plot was a complete failure.

Our nematode friends

Not all nematodes are "baddies," some are beneficial to us. Some nematodes attack grubs, root maggots, cutworms and the "bad" nematodes instead of fruit trees and vegetable plants. I once purchased what I was told was several million beneficial nematodes (I couldn't see them as they are too minute to view without the aid of a microscope). These beneficial nematodes do not occur naturally in sufficient numbers to offer the level of control needed, but science has come to our aid, we can buy them to use as a natural pest control. This beneficial army of nematodes can travel through moist soil seeking out of the soft bodies of insect larvae, making for happy gardening naturally.

The beneficial nematodes are so tiny their little bodies dry out and they will die quickly if exposed to the air or sun. They live primarily underground in darkness and are generally ineffective against surface pests. The beneficial nematodes occur naturally in soils throughout the world and are exempt from EPA control. Water plants to keep them alive. If they are left in the sun or otherwise mistreated during shipment they could be DOA. They are sent by airfreight but they should be sent out on Monday so they won't be held over on a weekend. You're working with a living organism being used as an insecticide, so they require great care in handling.

We still have a lot to learn about nematodes. Perhaps the most crucial factor for the success of beneficial nematodes is soil moisture. You should water thoroughly before and after applying the nematode solution to your land. Dry soil means certain death to your good nematodes. Niles Kinerk of Gardens Alive recommends applying one-half to one inch of water daily for three days after application. Before applying the nematodes all plastic or heavy mulches should be removed or raked back. The mulch can be replaced after application.

It is best to apply the nematodes in the evening as they are very sensitive to ultraviolet light. They move best in sandy loam soil and very slowly in clay. Use double strength to control such insects as root maggots, grubs and mole crickets in lawns.

These nematodes are beneficial to gardeners and farmers alike. They, like lizards, frogs, wasps, toads and birds, are truly a living insecticide, seeking out insect hosts and entering their bodies through natural openings.

The beneficial nematodes are shipped when dormant and arrive in a moist medium that looks like Styrofoam or polyfoam that you mix with water for application. When they arrive, place the sealed container in your refrigerator until you are ready to use them but don't wait too long to put them to work for you--their effectiveness may decline in just two or three weeks. (I am using them against the papaya fruit wasps that lay their eggs in the papaya fruit.) Once they are mixed with water they are viable only a very short time, so don't try to save some for later application once you have mixed them. It is better to spray them on the ground around your plants and hose them down.

Sources of beneficial nematodes:

The following mail order companies offer Steinernema corpocapsae nematodes (brand names include Bio Safe and Scan Mask):

* Gardens Alive, 5100 Schenley Place, Lawrenceburg, IN 47025; 812-537-8650;

* Peaceful Valley Farm Supply, PO Box 2209, Grass Valley, CA 95945; 916-272-4769; www.groworganic. com

* Richter's Goodwood, Ontario, Canada LOC 1A0; 905-640-6677;

* Ringer Corp., 9959 Valley View Rd., Eden Prairie, MN 55344; 612-703-3300

So when you garden, use compost, manure and mulch. I'll bet you were not aware of all that activity going on in your garden right beneath your very feet.

Europeans and Asians have used seaweed as mulch for hundreds of years. I use a liquid seaweed nutritional foliar spray on all my plants especially my papayas, citrus and banana trees. The plants feed through their stomata, an opening on the underside of their leaves.

The cost of the spray is very low, about 5 cents per gallon after the water is added. I cover my large lot of 1/3 acre every couple of weeks for less than $1. The seaweed contains about 60 trace minerals that feed the plants, like a vitamin-mineral supplement. The plants are healthier, a little more resistant to drought, disease, insect attack and frost damage. A strong healthy vigorous plant only gets that way when it comes or grows in a healthy and balanced soil.

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