Accurate identification of cucumber cataplexy and the latest prevention and control technology
Winter to spring, all kinds of vegetables are beginning to prepare seedlings, due to the frequent occurrence of spring cold in spring, the weather is rainy, cold and humid, the temperature is changeable, resulting in a large area of cataplexy disease, often causing large areas of vegetable seedlings to die.
1. Symptoms of onset
1. Rotten seeds: After sowing, they are infected by pathogens before they germinate, resulting in rotten seeds.
2, rotten buds: seeds just germinated or before they are unearthed before they are invaded by germs and rott buds.
3. Cataplexy: seedlings are most susceptible to infection when 2-4 leaves, water-stained light yellow-green spots appear at the base or middle of the stem, and then become yellow-brown, and after the spots go around the stem for a week, the stem base overflows into a linear shape; when the seedlings are lodging in pieces, when the humidity is high, white cotton flocculent hyphae grow near the diseased plant.
Symptoms of onset of newly unearthed seedlings
The cotyledons have just developed symptoms of the seedlings
Symptoms of larger melon seedlings
2. Pathogens
The pathogens of vegetable plex are a variety of putrefactory molds (pythium spp.), all of which belong to the fungus of the subphylum of Flagella, and the more common ones are melon fruit rot mold and debali rot mold. The white cotton flocculent seen in the diseased part is the mycelium of the pathogen, filamentous without separation, and the hyphae produce irregularly shaped, petal-like or oval sporangia, which germinate to produce zoospores; the sexual reproduction of the pathogen produces spherical, thick-walled oviospores.
Third, the factors of occurrence
1, seedbed environment: low temperature, high humidity is conducive to the onset of the disease. Poor ventilation of the seedbed, insufficient light, and large humidity, which can easily induce cataplexy.
2, cultivation management: the application of unripe manure in the nutrient soil is conducive to the onset of disease; the seedlings are too dense, 1 to 2 seedlings at the true leaf stage, because the nutrition of the cotyledons has been basically used up, the new roots have not been solid, the self-nourishment ability of the true leaves is weak, the disease resistance is also weak, and it is also easy to be infected with this disease.
Fourth, the law of pathogenesis
1. The pathogen overwinters in the topsoil layer of 12-18 cm with oospores and survives in the soil for a long time. In the following spring, when the conditions are right, germination produces sporangia, and zoospores or diameter sprout tubes invade the host.
2. Fungi that live in saprophyte in the soil can also produce sporangia, and zoospores infect melon seedlings to cause cataplexy.
3. Reinfection in the field mainly relies on the production of sporangia and zoospores on the diseased seedlings, and the rhizomes close to the ground are attached by irrigation water or rainwater. After the invasion of the pathogen, it expands in the parenchymal cells of the cortex.
Fifth, prevention and control methods
1. Seedbed selection: choose land with high terrain, low groundwater level, good drainage, leeward to the sun, fertile soil and no germs.
2. Soilless seedlings: seedling tray, nutrient bowl and soilless substrate seedlings are adopted.
3, seedbed management: maintain suitable temperature and humidity, air temperature 20-25 °C, soil temperature 16-20 °C, enhance light. Prevent over-dense sowing, grow seedlings, and find diseased seedlings to be eradicated in time to increase ground temperature and reduce soil moisture. After the seedlings are unearthed, ventilation should be gradually strengthened, the air humidity should be reduced, and the soil should be cultivated in the middle of the cultivation. On cloudy, rainy and snowy days, it is also necessary to remove the grass and carry out a short period of ventilation and moisture removal around noon. If the temperature is too low to affect the ventilation, heating measures can be taken to increase the temperature and then ventilate. After the bad weather is clear, the grass on the installation cannot be fully uncovered, and pay attention to ventilation.
4. Seed treatment: Before sowing, it can be soaked in 55 °C warm water for 15 minutes and then germinated and sown. It is also possible to use 10% phenylethicazole suspension seed coating 10 ml, or 2.5% rochonitrile suspension agent 10 ml, or 6.25% fine nail & middot; 10 ml of 150-200 ml of water coated seeds of 10 ml of 10 ml of 3 kg of seeds can effectively prevent seedling stage cataplexy and seedling stage diseases such as standing blight and anthrax.
5. Biological control: when preparing the seedbed, 250 grams of "5406" bacteria are applied to each square meter of seedbed, which can inhibit the occurrence of cataplexy; or 250-300 grams of seeds are mixed with 5 grams of yielding bacteria and then sown. When it occurs individually or just occurs, it can be sprayed with 5% wellgangmycin aqueous agent 800-1000 times liquid, combined with wind and humidity.
6. Pharmaceutical prevention and treatment: at the beginning of the disease, 72.2% downy mildew hydrochloride water agent 600 times liquid, or 68% fine nail cream ling &middot can be selected; Manganese zinc water dispersible granules 600-800 times liquid, or 69% enoylmorpholine & middot; Manganese zinc wettable powder 600 times liquid and other spraying prevention, seedbed humidity, timely ventilation and moisture removal, every 7-10 days prevention and control, continuous prevention 2-3 times.