Nematodes are a real disaster. They are very small and difficult to notice, but the consequences of such inattention will cost you dearly. These worms can ruin the harvest of both garden crops and garden crops. They are very fond of parasitizing on indoor plants. Let’s figure out what these pests are, and how to deal with them.
Carrots affected by nematodes. Farmer Burea-Uinsurance.com Government of Western Australia
General description of nematodes
Nematodes, or Roundworms (Nematoda, Nematodes) – a type of worms (according to other classifications, nematodes are a class of the type of roundworms, which also includes gastric worms).
One of the largest types in the animal kingdom. About 30 species have been described, but the real diversity is much higher. Based on the rate of description of new species and the degree of specialization of insect parasites, it can be assumed that the real number of species is about 000.
Many types of nematodes are parasites of plants, animals and humans (roundworm, trichinella, hookworm, rishta, etc.). Free-living people live in the seas, fresh water bodies and soil. They cause nematode diseases of plants, in animals and humans – nematodes.
The body length of nematodes is from 80 microns to 8 m (this is the length of the parasite Placentonema gigantissima, which lives in the placenta of the sperm whale). The body of nematodes has a fusiform shape, tapering at the ends. In cross-section, the body is round and has bilateral symmetry.
Varieties of nematodes – plant parasites
Nematode plant diseases are caused by a number of harmful plant-eating nematodes. Found in many wild and cultivated plants. Most often, the external signs of nematode lesions of plants are manifested by a slowdown in the emergence of seedlings, the growth and development of seedlings, weak flowering, partial (sometimes significant) death of plants at a young age, a decrease or loss of yield.
In the process of feeding, nematodes violate the integrity of the roots, thereby facilitating the penetration of pathogenic fungi, bacteria and viruses into the plant. The introduction of nematodes into the roots of plants usually causes strong branching of the root system and rotting away of small roots, the formation of galls of various shapes, pointed swellings, ulcers, leading to the death of the roots.
Stem and leaf nematodes
Stem and leaf nematodes cause fusiform thickening of the stems, underdevelopment of the leaf blade and its deformation. Leaves affected by leaf nematode are covered with dry necrotic spots of irregular shape, located in a chaotic manner. Most often, leaf nematodes damage garden strawberries, nephrolepis, chrysanthemum. The stem nematode is found on vegetable crops: onions and garlic, parsley, parsnips, tomatoes, radishes, and cucumbers.
Nematodes. Farmer Burea-Uinsurance.com CSIRO
The beet disease caused by the nematode was called beet fatigue (beet fatigue) of the soil, since its appearance was attributed to the depletion of the soil and its depletion in potassium salts; but then the true cause of the disease was clarified thanks to the research of Kuhn and others.
The harm caused by the nematode consists in the browning of the leaves and in a decrease in the size and weight (by 2-3 times) of the root of the plant, and the latter often completely rot. The amount of sugar in diseased beetroot is reduced by more than 6%. With the colossal fertility of the nematode, it can very much harm beet plantations.
Roundworm of the Heterodcridae family. Body length about 1 mm. It parasitizes on the roots of potatoes (less often on tubers), tomatoes, and sometimes on black nightshade. The potato nematode is found in Europe, Asia, North and South America, Africa and Australia.
Development from a larva to an adult individual of a potato nematode takes place in the tissues of the root (tuber) of the plant. Worm-like transparent males crawl out of the root into the soil. Females remain attached to the root (tuber) with the head end; the swollen body, covered with a thick cuticle, protrudes outward.
After fertilization, the male dies, and the female forms over 1000 eggs, which remain in the mother’s body, which turns into a cyst after her death. In the spring, the larvae emerge from the cyst and invade the roots of plants.
The potato nematode inhibits the development of potatoes, significantly reducing the yield; with severe infection, tubers are not formed or only 1-3 small tubers grow.
Filamentous worms are a large group of parasitic worms of the nematode class that cause galls on plant roots.
Males are vermiform (length up to 2 mm), females are swollen, egg-shaped (length is about 1 mm). They are polyphagous, infect over 2 thousand species of plants (including vegetables and industrial crops, ornamental and herbaceous plants, trees and shrubs).
Development takes 19-45 days. The female inside the gall lays up to 2 thousand eggs during her life. The larva of the nematode developing in the egg passes the first molt in the egg, hatches, penetrates the root and intensively feeds on the juices of the host plant, turning into an immobile female or a mobile male leaving the gall in search of a female.
The growth and development of the nematode is facilitated by moderate soil moisture and temperatures in the range of 20-30 ° C. In some growing areas, soil pH levels of 5.5-5.8 are favorable for nematode development. Other factors such as soil type and organic fertilization also affect the life cycle of the nematode.
External signs of plant damage by nematodes
Plants affected by nematodes are stunted, tend to curl in warm weather, and form very few fine roots. Small lesions appear on the roots, rounded or elongated in shape. At first, these lesions are dull yellow in color, then, as the disease progresses, they become darker brown. Depending on the degree of damage, infected plants grow poorly and show signs of water and nutrient deficiency.
It should be remembered that in some plants small bulges or bulbs form on the roots. They serve to store nutrients. For example, arrowroot, chlorophytum.
Signs of tomato root nematode damage. Farmer Burea-Uinsurance.com Ohio State University
Signs of nematode damage on plant leaves. Farmer Burea-Uinsurance.com Clemson University
Signs of corn nematode infestation. Farmer Burea-Uinsurance.com Purdue University
Nematode control measures and methods of prevention
Crop rotation is one of the simplest ways to prevent the spread of nematodes on the site. Nematodes are pests of a specific plant and cannot feed on anything other than the host plant. Therefore, it is necessary to draw up a crop rotation scheme so that after infection with a nematode in the affected area for several years not to grow the affected crop.
During this period of time, the larvae of the nematode should gradually die. The difficulty in dealing with nematodes in this way is that they have the ability to remain viable for a sufficiently long period of time.
For planting, use only healthy plants, cuttings.
Spray indoor plants no later than five to six hours, the leaves after spraying should dry out before night.
If the room temperature is very low, keep the plants dry.
Some nematode species die when the soil dries out. They can be destroyed by scattering the soil in thin layers and letting it dry thoroughly.
To avoid nematode infestation of indoor plants, do not use untreated garden soil for indoor plants. Before use, the earth must be calcined or steamed.
Attention! Caution should be exercised when using potent nematode killing agents as they are highly toxic and can be dangerous.
Fight with systemic and contact poisons. The destruction of nematodes is carried out by spraying plants 2-4 times with an interval of 3-5 days with a 0,02% solution of mercaptophos, lindane (ruskamine) or phosphamide (BI-58, RAGOR). However, they do not kill eggs in their hard chitinous shells. When the poison wears off over time, the parasites will hatch.
One way to deal with a nematode is heat treatment of roots… The affected plant is removed from the ground, the roots are washed from the ground. Then the roots, and for a short time the whole plant can be bathed in water at a temperature of 50-55 ° C. This temperature exposure is one of the most reliable means of root pest control, because the optimum temperature for nematode reproduction is 18-24 ° C, and at temperatures above 50 ° C the nematode dies.
This temperature is safe for plants and reliably destroys pests.
The eggs of nematodes are the most resistant to changes in living conditions. There is still no reliable data on the duration of the heat exposure: it ranges from 5 to 20 minutes.
Everyone can imagine how laborious the hot bath described above is. Many amateurs in such cases, in case of plant diseases with a nematode, simply cut off the roots. It costs the plant considerable strength to form new roots. Therefore, heat treatment is preferable.
Small doses of contact poisons containing verkema-ruskamine should be mixed into the ground. The systematic implementation of these operations will completely clean up even a large collection.
How do you deal with this scourge? We will be glad to hear your recommendations in the comments to the article or on our Forum.