A common pest that negatively affects the crops of agricultural and ornamental crops is a nematode. It not only inhibits the development of the plant, but can also cause its death. This pest is a tiny worm. It causes great economic damage to private and industrial farms.
Pest Description
Often in nature, an onion nematode is found. It causes rotting of root crops and other onion varieties. Both the root and the stem of the plant suffer.
After infection, the root crop becomes unfit for consumption. And deformation of the protective layer of the bulb often causes the development of secondary infections and diseases.
As indicated above, the onion nematode is a small worm. The body of the pest is white, threadlike. Length - up to 1.5 mm. On the front of the nematode’s body is a stylet — an organ in the form of a needle. With its sharp tip, the pest infects the soft parts of seeds and plants.
Dangerous parasites for crops
The nematode’s nutrition source is onion tissue and cell juice. Such a diet allows the pest to multiply inside the vegetable, to lay larvae in it. A female can lay several hundred larvae in one season. And favorable conditions contribute to the development of up to 6 generations of new pests.
An increase in population negatively affects sowing. The damage to the crop can be colossal. Active reproduction of the parasite can continue even during storage of the crop.
Scientists claim that the onion nematode is a type of roundworm, which, like parasites, is considered the most common in the world. This worm is especially common in temperate regions. These are ideal conditions for his survival. It has been proven that during seeding infection, the parasite can destroy almost 80% of the total crop.
In addition to onion nematodes, in the fields you can find less common varieties of this pest. Often this worm infects carrots, garlic, legumes and potatoes.
Life cycle features
Onion nematode is a type of worm. Like most of them, this parasite is migratory. Throughout its entire period of existence, the parasite constantly changes its habitat. Sometimes a plant does die from exhaustion.
The development of the nematode occurs in the egg, which the adult female lays in the soil or plant. After growth, which lasts very little time, the first molt occurs. A larva appears. From this moment, the pest begins to parasitize. It feeds on the surface layer of the rhizome, the sap of the plant or its internal part. The development of an individual lasts about 1.5 months. During this period, the pest molts 4 times, gradually changing one stage after another.
After mating with the male, the female lays eggs again in the most comfortable conditions.
The life cycle of a nematode lasts 4-8 weeks. During this time, many other larvae may appear that can quickly destroy the entire onion planting.
Ideal conditions for the development of an individual is a moderately moist soil, warmed up to a temperature of 15-20 o C. When the onset of cold weather, the nematode falls into suspended animation. In this case, the worm can be present both inside the plant and on its surface or in the soil. In this state, the pest can be up to 5 years.
Soil is the temporary habitat of the worm. All stages of its development occur inside the root crop. At the same time, in one bulb can be simultaneously up to 15,000 individuals who will feed on the juices and tissues of the plant.
Worm Nutrition Features
An onion nematode is a type of roundworm that has a stitching mouthpart. As soon as the worm is near the plant or inside it, the parasite pierces its tissue with a stylet. Thanks to its digestive enzyme, the individual begins to consume plant nutrients. This substance disrupts the normal development of the rhizome and its functioning. After some time, this can lead to a halt in the growth of the plant and its further death.
In fact, nematodes are finicky in nutrition. They selectively approach food. In dead and weak tissues, they cannot parasitize, therefore, after complete depletion of the bulb, they immediately move to a healthy, full-fledged root crop. Such migration also contributes to the rapid destruction of the entire crop. Therefore, it is necessary to timely detect the defeat of the crop with an onion nematode. Measures to combat this parasite are quite diverse.
Signs of crop failure
The parasite of the plant can be seen at any stage of plant development. The defeat of the onion by the nematode can be seen by such external signs:
- The surface of the bulb is loose, the structure is rotten.
- The stem and leaves are underdeveloped, stunted.
- Leaves dry, do not recover after watering. The color of greenery changes.
- There are cracks all over the husk; it quickly falls off at any touch.
- The bottom becomes soft, it may fall away.
At an early stage of infection, the first leaf is bent, slightly swollen. Over time, the bulb grows, and these changes become more noticeable and pronounced.
Later infection is more difficult to detect. In this case, whitish spots appear on the bulbs, the skin flakes become fleshy and thickened.
The active life of the parasite changes the color of the onion tissue from white to gray or dark brown. Cavities between the scales appear, and the root crop becomes loose and soft. Foliage turns yellow, curls.
How to deal with a nematode?
As you can see, the onion nematode can bring a lot of trouble. Control measures consist of comprehensive procedures. After all, this worm for a long time can be in the soil in a state of suspended animation, without showing any activity. But often the infection of crops occurs in the spring, when favorable conditions for development are around. Often at this time there is a sufficient parasite population on the site. So, it is possible to predict the appearance of nematodes:
- using chemicals;
- annually changing ornamental or vegetable crops for growing on a specific plot of land;
- observing the rules of storage of the crop;
- processing seed, carefully selecting seeds.
If the seed is already affected by nematodes, experts advise the use of chemicals that affect the parasite at any stage of development.
Drugs for the fight
So, how to deal with the onion nematode? The most reliable and popular means to destroy the pest population is recalcite. This drug is oxygen-containing. Often it is used as fertilizer, but can be used to combat microorganisms. This drug allows you to destroy not only adults and sexually mature individuals, but also nematode cysts with eggs.
Use the product only in dry weather, treating the entire sowing area immediately before planting in 7 days. Recalcite is used at the rate of 250 g / m 2 .
Often, carbamide is used to combat the onion nematode stem. It is introduced into the soil immediately a month before sowing. Make the drug at the rate of 100 g / m 2 .
Ammonia water is very rarely used. This tool not only helps in pest control, but also allows you to saturate the soil with nitrogen. The required dose of the substance is 250 g / m 2 .
Folk ways of struggle
Many summer residents prefer to use their own, environmental control measures - folk remedies. Onion nematode, according to studies, after such procedures may partially disappear from the territory. But nevertheless, folk remedies are considered by specialists to be an ineffective method. So, let's look at several popular ways that modern summer residents use.
- Seeds must be poured with hot water (temperature about 45 degrees) and left for 1 hour. After complete drying, the bulbs are ready for planting.
- You can also decontaminate the seed by pouring it with infusion of wood ash for 2 hours. Before planting, the seeds must dry.
- Before planting, the bulbs can be warmed in the oven at a temperature of 42-45 degrees. It is advisable to perform the procedure 10 hours before disembarkation.
- You can disinfect bulbs by pouring them with a solution of potassium permanganate or formalin. Planting stock should be in the solution for about a day.
- Some summer residents use a 1% salt solution.
Although experts claim the low effectiveness of folk remedies in the fight against nematodes, they can be safely used to prevent infection of the site. Such manipulations will avoid mass infection, which means that the crop will be saved.
Prevention of infection with nematodes
One of the most reliable ways to obtain and preserve the crop is to prevent infection. Regular treatment of the plot minimizes the likelihood of developing onion nematodes. Photos of the affected plants clearly demonstrate that vegetables become unfit for food. Prevention consists of the following activities:
- It is imperative to regularly change the landing site of a particular crop. This alternation allows not only to protect plants from pests, but also to improve the condition of the soil.
- Before planting, seed must be treated with special disinfectants. It can even be hot water. The most commonly used chemicals.
- Immediately after harvesting, it is necessary to clean the area from plant debris, weeds and diseased plants.
- After harvesting, the soil is dug up and inorganic fertilizers are applied.
- If the site is affected by nematodes, it is necessary to use high-quality chemicals. They will be able to eliminate 100% of the pests.
- Be sure to follow the rules and conditions of storage of the crop. Pay attention to humidity, temperature and lighting in the room where the crop is stored. After all, the larvae of the parasite can be in the plant for a long time, and then become more active.
Correct preventive measures will allow not only to obtain and preserve the crop, but also to reduce the risk of soil contamination by other pests.
Regular processing of the plot, constant monitoring of the state of the plants - this is the key to obtaining a healthy, good harvest.
Varieties of onions and nematodes
To date, there is no onion variety that is resistant to the effects of this parasite. But Bamberger's bow is less susceptible to this pest. But the onion variety Bessonovsky, on the contrary, is unstable. Therefore, the main thing is not only to choose high-quality, proven seed, but also to regularly monitor the state of seedlings.
Conclusion
The onion nematode is a small parasite that is almost invisible to the naked eye. The danger of this roundworm lies in the fact that it can be in a state of suspended animation for a long time both in the soil and in the seed. Therefore, special attention should be paid to preventive measures that indicate how to deal with the onion nematode. So you save not only a quality crop, but also the soil health of your personal plot.
If infection with nematodes has already occurred, it is recommended to immediately use special effective chemicals. They allow you to completely destroy all individuals that affected root crops.