The "Queen of the Fields", like other crops, is not immune to attacks from pests and diseases. In order to select successful methods and organize the fight against them, it is important to know what diseases and insects can infect corn.
Diseases of corn
Infection and development of various diseases of corn has several reasons:
- poor seed quality;
- small amount of knowledge and experience in growing a plant;
- lack of prevention and poor quality control of sources of diseases and pests.
All threats must be eliminated at an early stage, otherwise the chances of preserving even half of the crop are small.
Diplodiasis
The cause of the disease is the fungus Diplodia zeae Lev. The disease affects the entire plant completely. On the ground part of the corn, a white bloom appears, similar to cotton wool. These myceliums often cover the inner leaves of the cobs.
With this disease, the caryopses become brittle, acquire a light brown color, black dots prevail on them and on the cob shafts.
With an advanced disease, the stems of the plant become fragile, and cracking occurs. In the near-stem depressions of the leaves, brown spots are visible, from which, in wet weather, olive-colored mucus, containing the spores of the fungus, is released.
Fungal disease spreads in humid warm weather, so this period falls on the end of the vegetative phase of development of the ears - at the end of August and the beginning of September.
The main source of infection with this fungal disease is seeds. When planting, most of them rot in the ground, and on small shoots, the fungus matures and actively spreads. Affected corn is not suitable for storage and use.
Methods of dealing with diplodiosis are reduced to the following activities:
- Choose and use healthy seed.
- Before sowing, treat the material with fungicidal solutions.
- Apply spring feeding as planned.
- Stay within the harvest time of corn, dry the cobs to a moisture content of 16%.
- Clean the area after harvesting from the remnants of the vegetable part of the corn, plow the land.
- Observe the crop rotation.
Helminthosporium leaves
The causative agent of the disease is Bipolaris turcica Shoem. The spread of the disease begins with the lower leaves of the corn, eventually capturing the entire plant. The leaves dry up, and when the root is infected, which happens less often, the whole plant withers.
The disease is active in July-August. Brown spots with dark outlines appear on the corn, and when dry, the central part of the spot brightens.
As the disease progresses, the spots merge, occupying the entire leaf surface. The source of the disease is plant residues after harvest.
Prevention measures are the same as in the fight against all fungal diseases:
- crop rotation;
- seed quality;
- feeding with phosphorus-potassium fertilizers;
- adherence to sowing dates;
- deep autumn plowing of the land after harvesting.
Cladosporium
The causative agent of the disease is a fungus of the genus Cladosporium Link. Popularly, the disease is called "Olive rot" because of the color of myceliums.
When infected, the upper parts of the ears are more often affected. The cause of the disease lies in the infected planting material. The mushroom is active at an air temperature of 12 ° C.
Protection methods involve burning the remaining vegetable part of the corn, deep plowing of the land. Responsible approach to seed selection and sowing.
Wilt
The causative agent of the disease - Bacterium stewarti - affects the vascular system of plants, destroys the tissues of the parenchyma. Bacteria, spreading through the vessels, clog them with mucus and poison them with toxins. They can penetrate into the ears and tissues of seeds, from which they become shriveled. Both the entire ear and part of it are affected. Sweet corn is most susceptible to wilt contamination.
If yellow stripes appear on the leaves of corn, then this is a clear sign of wilt.
If a wilt is found on young plants, before the corn throws a panicle, they should be mowed and sent to silage production. Burn the rest of the plants, plow the land. It is necessary to observe the crop rotation, use only healthy seeds.
Dusty corn smut
The cause of the disease is the Ustiliago tritici fungus, which spreads in hot weather. It is impossible not to notice the black mold on the cobs and panicles. The fungus destroys them, although the ripened grain remains may not differ from healthy ones.
When touched by mold, black dust scatters, scattering the spores of the fungus. Partially washed away by rain and watering. When infected, the corn becomes bushy, lags behind in development, the ear does not ripen, but turns black and dries up.
The disease cannot be cured, the plants are destroyed by burning or burying them in the ground to a depth of more than 0.5 m. The place of growing corn for the next year needs to be changed.
Bubble smut
The causative agent of the disease is the mushroom Ustilago zeae. Bubble smut is a disease that affects the entire ground part of the plant. Pink or green rot appears on it, which grows over time, increasing in volume and changing color to gray. Ripening areoles burst, and spores scatter across the territory, infecting all large plantations.
This mushroom loves a dry and hot climate, so a culture sown later is more susceptible to disease. The corn yield is reduced by up to 50% with a blister smut infection.
For prophylaxis, seed treatment with potassium permanganate or special preparations is used. For example, "Ditox" has a wide spectrum of action and is not washed off by watering or rain within an hour after spraying. The introduction of complex fertilizers as nutrition for this agricultural crop is of great importance.
Choose varieties of corn and its hybrids that are resistant to disease, observe the crop rotation.
Fusarium
The cause of the disease is an imperfect Fusarium fungus that develops on corn during any of the growth stages. Visually determined by the presence of swollen irregularities on the stem of the plant, under which the fungus develops.
When planting infected seeds, covered with a layer of white-pink bloom, seedlings are poor, and the emerging corn is weak, slow-growing. The process of stem and root rotting begins when the corn cobs reach milk maturity. The leaves of the plant dry up, and the cobs gradually turn black.
Fusarium is active in cold weather with high humidity levels or in drought conditions at temperatures of about 30 ° C.
Remove diseased plants as early as possible, uprooting them from the ground and burning them. Mandatory autumn plowing and dressing of healthy seeds before planting.
Stem rot
A fungal disease, in which the leaves of corn turn gray-green, as the fungus multiplies, the plant becomes covered with a bloom of pink. Under its action, the leaves dry out and fall off, and the stem rots, becomes soft and breaks.
The fungus loves hot, dry weather. It develops with improperly organized watering and dense planting of plants. It is preserved in the vegetable part of the corn after harvesting the cobs.
Preventive measures are reduced to adherence to the technique and timing of planting, seed treatment with fungicidal solutions. After harvesting, it is necessary to clear the area from the remnants of corn and dig it up.
Maize pests
In addition to fungal and bacterial diseases, a high yield is threatened by various pests of corn. They damage the ground part of the plant and its root system. Another danger is the spread of fungal diseases by pests. Therefore, this problem requires an urgent and correct solution.
Root aphid
It spreads in hot weather without precipitation. It is a very small transparent white insect. It tolerates low temperatures well in winter.
When corn is attacked by root aphids, it lags behind in development, and the leaves turn yellow and dry out. Root aphids are carriers of fungal diseases. Therefore, if it is detected, plants should be treated with fungicidal agents.
If pests are abundant, then the fungal disease is in active form. Destruction of corn and subsequent cultivation of the land is recommended.
An important measure in the fight against root aphids is weed control. Seeds for sowing should be used only treated with insecticides. These include: "Aktara", "Mospilan", "Dantop" and others.
Wireworm
The wireworm larva looks like an orange-brown worm, shiny and smooth. Their vital activity takes place in the ground. They get inside the plant and feed on its sap. Corn dries out due to lack of nutrients. The insect is active during drought.
The wireworm prefers moist and acidic soils, with thickets of creeping wheatgrass and burdock.
To combat this pest, a lure method is used. Potato peels, straw, hay are placed in small holes and covered with a board. When the wireworm is trapped, it is collected and burned. This procedure is carried out several times.
When digging, the larvae end up on the surface of the earth, where they die during the first frost. Crop rotation will lead to the fact that when planting in the next season in place of corn unloved wireworm plants (mustard, buckwheat, legumes, etc.), most of the wireworm will die of hunger.
If such measures do not help to destroy the pest, then they resort to the use of chemicals. They are used strictly according to the instructions, since many of these drugs are toxic and unsafe for humans and the environment.
Preventive measures are reduced to weeding, watering the corn, dressing the seeds and applying fertilizers to boost plant growth and reduce soil acidity.
Stem moth
The danger to the plant is not caused by an adult moth, but by its caterpillar, which is colored yellow-green and reaches a length of 25 mm. Appears in dry weather with high air temperatures.
Caterpillars destroy young leaves, and then harm the ears and pistils, which is reflected in slowing growth and reducing crop yields. Such caterpillars are harvested manually or the corn is treated with special solutions ("Decis", "Stefesin"). Such treatment destroys insects, but harmful substances do not accumulate inside the plant.
The difficulty in dealing with the stem moth lies in the fact that the caterpillars live on the cob and inside the stems. Therefore, several drugs are often used in combination. For example, "Aktellik 50ES" and "Karate Zeon 050CS". Insects die from contact with insecticide and inhalation of its vapors.
If one treatment is not enough and the presence of tracks has only decreased, it is recommended to carry out another procedure.
Swedish fly
The larvae of the Swedish fly are dangerous for corn. They are a worm-like insect of white-yellow color up to 0.5 cm long. They tolerate humid and cold weather well. They eat the plant during germination.
The perforated leaves turn dark green, as the plant tries to heal itself and sends all its forces to damage. Summer generations feed on the tissues of milk cobs, causing irreparable damage to the crop. The damage caused affects the development of corn, the yield drops by 40-50%.
To prevent Swedish fly attacks, it is recommended:
- seed treatment before planting;
- on early shoots, treatment with the drugs "Tsiperon", "Sumi-alpha";
- the introduction of spring dressings to stimulate the active growth of corn;
- loosening, watering.
Most of the fungal diseases of corn are not treatable, and plant pests, in addition to their damage, spread dangerous spores. Therefore, preventive measures are of fundamental fundamental importance for growing crops and producing rich, healthy maize crops. Do not neglect knowledge of plant care and soil preparation before sowing and after harvesting.