Sunflower diseases and measures to combat them: how to neutralize an invisible enemy
Oilseeds are the most productive in the world, but they are most susceptible to all kinds of fungal diseases. Therefore, in order to protect your crop, you need to know the most common sunflower diseases and measures to combat them. Indeed, if several specimens become infected, then this can lead to the destruction of all crops. Fungal or viral microorganisms multiply quickly and spread over great distances. In this regard, it is necessary to learn to recognize the ominous symptoms of diseases in the early stages of their development.
Sunflower diseases and control measures: a cheat sheet for an agronomist
The main reasons for the active development of harmful microorganisms:
- Weather. Constant humidity and heat lead to their rapid reproduction.
- Natural features of the area. The quality, composition and structure of the soil affects the life of the spores.
- Violation of agricultural technology. If you do not adhere to the rules of planting crops, do not harvest in time weeds and do not treat the plantings with chemicals, then contamination cannot be avoided.
- Improper harvesting. Plant residues contribute to the development of sunflower diseases and control measures are canceled out.
Considering these 4 factors, many farmers were able to save up to 80% of the harvest. However, fungal spores are so tenacious that you cannot get rid of them. Mostly pathogenic microorganisms live in the soil. It is she who is the breeding ground for such harmful colonies. Therefore, you need to know your invisible enemies by sight.
In most cases, farmers can sow already infected planting material. Therefore, it is better to buy hybrid varieties of crops that are immune to fungal infections.
Downy mildew of sunflower - death with a white tint
The causative agents of the disease enter plants through the ground. As usual, the remains of infected crops together with mycosis spores overwinter in the soil. In spring, young seedling roots absorb nutrients from the soil along with pathogenic pests.
The characteristic features of sunflower downy mildew are:
- short stature, lethargy of sprouts;
- thickened stem;
- shortened internodes;
- corrugated leaves;
- highlighted veins on deciduous plates;
- grayish-white bloom under the leaves.
There are several forms of development of this disease. It all depends on the moment the culture is infected. If this happened at the germination stage, then the sprouts do not even have time to fully develop. The first signs of the withering process: thick stems, dwarfism and white bloom. Sometimes the mycelium infects adult specimens. As a result, the veins of the leaves change their shade, and myceliums appear on their back side.
There are also hidden forms of manifestation powdery mildew:
- longitudinal opening of the stem will show the presence of mycosis (the cut will have a white-brown color);
- during flowering, dried areas of plant fibers appear on the caps;
- the seeds are infected, although outwardly there are no signs.
In such cases, powerful fungicides for sunflower are most often used, which inhibit the development of infection.Before sowing, seeds are recommended to be etched with Protect. For 1 ton of planting material, up to 12 liters of working fluid are consumed.
The farmer's arsenal should contain one of such fungicides as Efatol, Derozal, Karbezim, Amistar-extra and Thanos. Spraying is carried out during the growing season with a working solution consumption of 200-400 l / ha.
Fomoz of sunflower - chestnut shade of death
The remaining parts of the plant or sown seeds can be infected with a dangerous disease - sunflower phomosis. Mycosis develops at high humidity, but moderate temperature (the ability to reproduce is lost when
+ 30˚С). Symptoms of lesion can be seen at the germination stage, with 5-8 leaves, or already on adult specimens.
The main signs of phomosis:
- leaves are covered with spots in the form of necrosis of a chestnut shade with a golden edging;
- dead areas of black appear on the stems (in the places where the leaves are attached);
- flower hats gradually darken, but they do not have a decay process.
If the defeat of phomosis occurs at an early stage of sunflower development, then in the end it quickly dries up and dies. At the same time, the culture does not even have time to form seed ovaries.
During the growing season, crops are treated with fungicides such as Derosal and Impact-K. In addition, experts advise you to follow the technique crop rotation... To do this, you need to keep a strict record of the crops planted in the field.
Sunflower White Rot - Vanilla Cradle of Death
Fungal microorganisms affect the sunflower at all stages of its development. In the lower part of the trunk, a cotton or flocculent coating is formed. Over time, the infected parts of the oil plant become dark brown.
Sunflower white rot often affects it:
- root system (processes acquire a soft structure);
- stems (the trunk becomes covered with gray-brown spots and becomes brittle);
- the back side of flower caps (light brown necrosis protrudes on them);
- seeds (darken).
This infectious disease is considered the most dangerous and destructive in agriculture. Due to the rapid development of mycelium, farmers lose almost 60% of the crop. Regrettably, charged specimens cannot be cured. The best method of dealing with sunflower sclerotinosis is prevention. For this, the seeds of the culture are treated with fungicidal agents before planting.
As the crops grow, they are sprayed several times with powerful preparations:
- Vesuvius;
- Glyphos Super;
- Chistopol;
- Click Duo;
- Dominator.
These are just a few of the sunflower diseases and how to control them. Still, you need to know that the oilseed crop suffers from bacterial wilting, broomrape, phomopsis and altenariosis. The best defense against them is to prevent their occurrence.