Onion pests control measures
Despite its acute character, the bow – «create» delicate and very vulnerable to diseases.
Culprits of disease – fungi, bacteria and viruses affect this valuable vegetable crop during the growth of plants and during storage.
Basically onion is suffering from a fungal disease, which include: Sakova and wet rot, downy mildew (downy mildew), cercopis, Anthracnose, Fusarium (rot of stems), green and black mold. Fungi reproduce by pieces of mycelium or spores.
The fungi help wind rain and insects that carry the spores from infected plants to healthy ones.
The plot mushrooms come from infected planting material and seeds; can survive in soil for up to several years.
Downy mildew is a widespread fungal disease that affects the entire plant — from the top to the roots.
Stimulating the disease the fungus overwinters in the bulbs of the hair, a stowaway and remaining in the soil and on plant debris and in seed material.
The disease is dangerous for its «secretive character» diseased bulbs are well preserved and in appearance does not differ from healthy.
After planting of infected planting material in the soil (sevka or turnips), a parasitic mycelium awakens from its winter slumber and gets to the intercellular spaces of leaves and arrows. This path continues up to 3-4 weeks.
Sick plant easily recognized by pale green spots, which gradually increased and covered by mycelium – rough touch of grayish purple.
Over time, the affected leaves turn yellow, wilt and dry up. The disease is causes irreparable harm to the testes.
Hands of a diseased plant turn yellow and cracked, the seeds become unviable or is not formed. As a result, the plant dies.
When the so-called secondary lesions when the spores from a diseased plant to a healthy fall, pathogenic infection and dry the leaves, penetrates into the follicle, where he holds the winter.
The disease progresses in a poorly ventilated places, with high humidity and moderate air temperatures from + 15°C to + 20°C.
Like any disease, the disease is easier to prevent than to cure. Measures are uncomplicated and even novice gardeners:
- — a place to land Luka choose a Sunny and well-ventilated (ideally, the direction of the beds from North to South);
- — separate the cultivation of different types of onions and testes;
- — timely removal of weeds, thinning crops (provides good ventilation of the crop);
- — alternate culture (re-farming in one place not earlier than through 3– 4 years);
- — use for planting high-quality, disinfected material (warming up planting the bulbs at a temperature of 45°C for 8-9 hours or blowing hot air, not later than 1 month before planting);
- — harvesting in warm,dry weather;- tab on the storage of well-dried onions (with the dry covering scales);- the destruction (burning) of crop residues;- post-harvest soil digging.
At the first sign of the disease the plants sprayed with one of the fungicidal drugs: mixture (1% ), copper oxychloride ( 30g. on 10 l of water), cinabon (0,4 % — 40 g per 10 liters of water).
The treatment is carried out regularly once in 10 — 12 days, but not later than 15-20 days prior to harvest. Testes treated to prevent, regardless of whether symptoms of the disease, and onions on a feather, on the contrary, it is strictly forbidden to spray chemicals.
In addition to the treatment with fungicides, planting periodically inspect and remove affected plants.
The defeat of plants by Cercospora «tell» appeared on the leaves the spots are grey-brown with yellow edging.
Anthracnose will be felt in black or dark green pads on the leaves. Struggling with these diseases like downy mildew.
Smut Luke strikes young onion (crops the first year). The leaves of diseased plants are covered with streaks of gray, of which there is a lot of black spores of the fungus.
In appearance they resemble glued in clumps. In severe cases the plant, a slurry of the spores can be detected on the bulbs.
Fungus «thrives in the soil, from where it falls on the plants. When sowing seeds, soil disinfected with lime with the addition of sulphur (50 g. of sulfur and 100 g of lime per 10 square meters).
The seeds themselves are coated with special substance TMTD (tirama), has protective and healing properties and is able to suppress the germination of spores of pathogenic.
Considerable damage to crops and other causes ubiquitous «onion problem» – rot. Onion bulbs are affected by gray (sheykovoy) rot, white rot, and rot the stems.
Sakova rot is the main enemy of onions harvested for storage. The infection occurs in the final stage of plant growth, when it starts to loose leaves, and at harvest, and the disease manifests itself in all its glory during storage (after 1 – 1.5 months after harvest).
In onion, the infection penetrates through the neck, where the tissue softens, acquires a yellow tint and become watery.
Under the top is dry (opaque) gray scales formed velvety plaque with small black tubercles. Gradually the bulbs are covered by a continuous black crust and shrivel.
Rotting of roots, and covering the stems of the onion a white fluffy coating with black dots will make themselves known head blight, also called white rot, and rot the stems.
The disease manifests itself by yellowing and withering of leaves and if the plant does not die, it is a parasitic fungus continues its activities in a stowaway follicles.
In the initial stages of lesion wet rot fungus «hides» under the outer layer of scales that have no obvious damage.
The defeat of the disease indicates the presence of a pink spot the end of the stem of the plant. Gradually diseased bulbs become brown color, soften and become slimy. Affected follicles produce the characteristic putrid odor.
Sources of disease — infected planting material and crop residues. When storing the harvest, the infection is easily transmitted from diseased bulbs to healthy, penetrating into them through Donets, or neck.
Excessive soil moisture and air, harvesting not ripe onions, as well as harvesting in rainy weather favors the development and spread of the disease.
Black mold strikes the bow much less than rot. The disease develops during storage, education, fluffy patches of black.
As a result, the infected pulp of the bulb cavity softens and turns into a powdery mass. «Contribute to» the development of the disease podmorazhivanie and mechanical damage to the follicles.
To protect crops from any kind of rot and mold will help:
- — collection and dispatch for storage Mature onions (leaves turn yellow, and the bulb – form a dense covering of scales);
- — harvesting in warm, dry weather;- post-harvest drying onions (at least a week at a temperature of about 30 C, with good ventilation or over);
- leaving the long neck (circumcision of withered leaves at a distance of 3-6 cm from the bulb);
- — drying and disinfection of storage before planting of the crop;
- — ensuring appropriate storage conditions of the crop (temperature from 0 to 2, the humidity level of 75-80%, without sharp fluctuations);
- — periodic inspection of the bulbs and removing the infected.
Early maturing varieties of onions and with a variety of dark scales, less prostrate to decay. Well kept grade – Strigunovskiy, Spassky, Bessonovskiy, Rostov.
Bacteriosis of onion refers to the so-called bacterial diseases, pathogens which bacteria. The «victim» of pathogenic bacteria penetrate the wound.
The disease affects onion sets, and seed. The leaves and arrows of plants turn yellow and die, the bulbs turn into a slimy mass and produce a sharp unpleasant smell.
«Spread» bacteria onion pests: nematodes, onion hurchalla and onion fly. Infection persists in infected bulbs, on plant debris and in the soil (about three to four years).
«Viral attack» Luke is unusual for the disease name, mosaic. It affects the leaves of all types of onions. Across the sheet appear bright narrow stripes.
The leaves themselves become corrugated, lose their shape and droop. Diseased plants strongly lag behind in growth, the inflorescence bent.
Spreading the virus with the juice of diseased plants mites, aphids and nematodes, and storage uses onion, which gains an elongated shape.
Struggle with bacterial blight and mosaic in the same way as with downy mildew, and rot: crop rotation, seed treatment, removal of infected plants, use high-quality, healthy planting material.