One of the most dangerous plant pests is nematodes (roundworms). They are microscopic in size, live in roots, stems, leaves and even fruits, and reproduce very quickly. Gall nematodes - pests that live in their roots - pose a great threat to plants. Penetrating into the tissue, parasites contribute to the formation of growths and swelling in them (galls), from where their name came from. What this is and how to deal with them will be discussed in the article.
Description
In nature, there are approximately thirty species of these worms. Some of them affect plants, others - animals, and others - humans. Further we will talk only about gall nematodes parasitizing in the roots of plants:
- Male nematodes are motile, in contrast to spindle-shaped immobile females. Their body is worm-shaped, 0.5–2 mm long, narrowed in front and rounded at the back.
- Larvae resemble the shape of a male, but smaller. The back of the body is more transparent and pointed.
- Eggs are microscopic, white in color. The female lays them in the so-called egg bags, consisting of a gelatinous film. One such bag contains a huge number of them.
At the end of the front of the gall nematodes (photo in the article) is a mouth opening, inside of which there is a stiff needle called a stylet. Using this apparatus, they pierce the root of the plant and suck out the juices. The worms have a small head, moving lips and tiny eyes. Outside, the body is covered with an impermeable but flexible cuticle, very resistant to chemicals.
Biology of Roundworms
They reproduce in two ways:
- The female is located on the root surface and lays eggs in a sac, the larvae of which first enter the soil, and then make their way into the root system of the host plant, after which it becomes infected.
- The female is completely located in the root tissues and lays eggs inside it. Hatched larvae move along the tissues of the root and settle in it for nutrition and development. They are no longer affected by biological methods of protection.
It should be noted that the larvae from the roots under favorable conditions are able to move across all organs of the plant.
The defeat of the root nematode
The most suitable conditions for their reproduction is increased soil moisture and air temperature above 18 degrees. The formation period of the root gall nematode is about a month. It can reproduce up to six generations a year. Pest affected plants have the following symptoms:
- depressed look;
- leaf curl;
- growth cessation;
- the formation of galls of a yellow hue;
- regrowth of many filiform roots (root beard).
It is very important to distinguish the galls of a diseased plant from natural thickenings of white color that retain moisture.
Where does the gall nematode come from
Nematode infection occurs through the soil and planting material. But it is quite possible to introduce tiny parasites using contaminated equipment, pots, and even with drops of water draining from the damaged plant when watering.
Nematodes can be found not only in the land of the garden plot, but also in the forest, composts and humus. And even purchased soil using greenhouse untreated soil can contain them.
Parasites on cucumbers
Tiny worms have terrible gluttony and fertility. They quickly and in large quantities accumulate in the soil, especially when the crop is planted in one place. Most gall nematodes on cucumbers, as well as tomatoes. Parasites, creating small thickenings in the roots, lay eggs, from which larvae appear, devouring everything around them. Eating the roots, the worms do not allow the cucumber to develop, depriving it of the ability to eat normally. The roots of the plant affected by the nematode become watery, with thickening of a brownish tint. The branches weaken, the leaves fall and the cucumbers die.
The difficulty lies in the fact that the pest due to its small size is very difficult to detect at an early stage of development. For prevention, we must not forget about crop rotation, changing crop cultivation on the site annually. Where these parasites appeared, plant garlic or cabbage instead of cucumbers. Nematodes do not tolerate these plants.
Open ground nematodes
In the European part with a temperate climate in open ground, two species of gall nematodes are observed:
- Birch - settles only on the roots of birch and is not particularly dangerous.
- North - lives in legumes, umbrellas, nightshade, buttercups and Asteraceae. Although the pest affects a huge number of plants, it does not pose a great threat to annuals. This species has only one generation per year and does not have time to settle in the roots of the plant in order to greatly weaken it.
Soon we should expect a new parasite on the territory of our country - the Colombian gall nematode. They already managed to bring it to Europe, and it successfully harms carrots, potatoes, beets, peas and many other crops of open and closed ground. As a result of damage, the specific weight of tubers decreases, and yield decreases. Losses reach up to 80%. It hibernates in the roots of cultivated plants and weeds, and is in the soil at the stage of eggs. Such a parasite reproduces sexually and asexually. The life cycle lasts up to four weeks.
Nematodes that are absent in Russia
There are four types of these pests that cause plant diseases, but are still absent in Russia. These include: Colombian, root, false Colombian and false gall. The countries from which they can be entered are Ecuador, America, Mexico, Chile.
One of the most dangerous and multi-eating is the root. The exact circle of its host plants has not yet been fully identified, but it is noted that the pest infects economically significant crops: beans, soy, eggplant, cucumbers, watermelons and tomatoes.
No less dangerous is the false gall nematode. Its main owners are potatoes and sugar beets. Infection with this species is possible through planting material (rhizomes, tubers) and soil. Worms of this kind form galls. They are most noticeable on sugar beets, from the thickenings of which come out numerous small roots. Symptoms of the disease appear on the fifth day after infection.
How to fight?
To combat the gall nematode, the following tools are used:
- Chemicals are the most effective: Rogor, Nemafos, Bi-58, Dimetoat. According to the instructions, the substance is dissolved, and the soil is treated with the resulting mixture. This procedure is carried out several times a season, because poisons kill only adults.
- Biological agents. Such substances are composed of natural components, therefore they are not harmful to plants and humans. Often use "Nematofagin." Before use, you must familiarize yourself with the instructions and clearly follow its instructions.
- Heat treatment. The plant is extracted from the soil, a part of the strongly affected roots is cut off, where galls are formed. Rhizome is immersed in water with a temperature of 50 degrees for five minutes. The soil is replaced with another, having a loose composition, adding an anti-nematode drug to it.
With a severe defeat, the plant is simply burned so that the pests do not find another victim.
Preventive actions
It is very difficult to detect and get rid of nematodes, so it is best to take care of preventive measures and prevent the appearance of these parasites. To do this, you must:
- thoroughly conduct autumn tillage;
- destroy weeds on time;
- Do not place plants with a closed root system from botanical gardens, greenhouses and shops in greenhouses;
- carry out cleaning of fallen leaves;
- observe crop rotation;
- regularly loosen the soil;
- fertilize the soil with organic matter;
- carry out periodically abundant irrigation of the land with subsequent drying;
- try not to overmoisten the soil.
One of the modern ways to protect greenhouses from pests is the use of sulfur drafts.
Conclusion
Parasites living in the roots of plants are dangerous pests, which can be difficult to detect. The main manifestations of the disease are the enlargements and swelling that appear on the root system. Having revealed such neoplasms, they conduct microscopic studies, because they are not always provoked by the presence of nematodes.