Integrated control of cucumber downy mildew

Cucumber, cucumber genus of Cucurbitaceae. Also known as cucumber and cucumber. The color of the fruit is oil green or emerald green, with soft spines on the surface. It is widely cultivated in all parts of China and is now widely cultivated in temperate and tropical regions. Cucumber likes warmth and is not resistant to cold, so it is one of the main greenhouse products.

Morphological characteristics of Cucumber

Annual trailing or climbing herbs; stems and branches elongated, furrowed, white hispid. Tendrils fine, undivided, white pilose. Petiole slightly scabrous, hispid, 10-16 (- 20) cm long; leaf blade broadly ovate-cordate, membranous, 7-20 cm long and wide, both surfaces very rough, hispid, 3-5 angles or lobes, lobes triangular, dentate, sometimes margin ciliate, apex acute or acuminate, base curved semicircular, 2-3 cm wide, 2-2.5 cm deep, sometimes base backward. Monoecious.

Male flowers: constant clusters in leaf axils; pedicels slender, 0.5-1.5 cm long, puberulent; calyx tube narrowly campanulate or subcylindric, 8-10 mm long, densely white villous, calyx lobes subulate, spreading, nearly as long as calyx tube; Corolla yellow-white, ca. 2 cm, Corolla lobes oblong-lanceolate, acute Stamens 3, filaments nearly absent, anthers 3-4 mm long, connective protruding, ca. 1 mm.

Female flowers: solitary or sparsely clustered; pedicels stout, pilose, 1-2 cm long; ovary fusiform, scabrid, with small spiny protuberances. Fruit oblong or cylindrical, 10-30 (- 50) cm long, yellowish green when ripe, rough surface, with prickly verrucous protuberances, extremely sparse and nearly smooth. Seeds small, narrowly ovate, white, without margin, subacute at both ends, ca. 5-10 mm. Flowering and fruiting in summer.

Growth Environment of Cucumber

Temperature: cucumbers like to be warm and not resistant to cold. The suitable temperature for fertility is 10-32 ℃. Generally, the growth is the best at 25: 32 ℃ in daytime and 15: 18 ℃ at night, the most suitable ground temperature is 20: 25 ℃, and the lowest is about 15 ℃. The most suitable temperature difference between day and night is 10: 15 ℃. The photosynthesis of cucumber was poor at 35 ℃, high temperature obstacle appeared at 45 ℃, and the cucumber was frozen to death at-20 ℃. If the seedlings were refined at low temperature, they could withstand the low temperature of 3 ℃.

Light: South China type varieties are more sensitive to short-day sunshine, while North China type varieties are not strict on the length of sunshine, and have become sunshine neutral plants, with light saturation point of 55000 lux and light compensation point of 1500 lux. Most varieties grow well under the condition of 8-11 hours of short-day sunshine.

Moisture: high yield and high water demand of cucumber. The suitable soil moisture is 60-90%. The moisture in the seedling stage should not be too much, and the soil moisture is 60-70%. In the result period, sufficient water must be supplied, and the soil moisture should be 80-90%. The suitable air relative humidity of cucumber is 60-90%. If the air relative humidity is too high, it is easy to get sick, resulting in a reduction in production.

Soil: cucumbers like wet but not resistant to waterlogging, like fertilizer but not resistant to fertilizer, it is appropriate to choose fertile soil rich in organic matter. The soil between pH 5.5 and 7.2 is generally preferred, but the pH value of 6.5 is the best.

Integrated control of cucumber downy mildew

Downy mildew is one of the main diseases of cucumber, which occurs from seedling stage to adult stage. The most susceptible period is after melon fruiting, when the air humidity is high and pathogens exist.

Symptoms of cucumber downy mildew: downy mildew is a high-temperature and high-humidity disease, which is also called Happy Horse dry due to its rapid disease. it is usually serious from March to April in spring, with chlorosis of mesophyll, polygonal brown spots limited by leaf veins, and gray-black (purple-black) mildew layer on the back of leaves. It causes the leaves to dry up and fall off quickly until the plant dies.

Comprehensive control methods of cucumber downy mildew:

Downy mildew is mainly prevented. Selection of disease-resistant varieties, control of field humidity, timely removal of old diseased leaves, ventilation and light transmission.

At the initial stage of the disease, 72% Kelou wettable powder 600x solution, 72.2% Pulicol water agent 400x liquid, 68.75% Yi Bao 1000 times liquid, and 25% Amisi 1500 times liquid foliar spray were used. You can also use Anke, Silver Farley, Pinrun, Baitai and so on. Once every 10 days, rotated for 2 or 3 times in a row.

The main results are as follows: 1. It is one of the important means to control diseases in greenhouse by using high temperature. This method can be used to control many kinds of diseases, such as downy mildew, powdery mildew, angular spot, gray mold, scab and so on. The specific method is around noon on a sunny day, after pouring through the water, the greenhouse will be sealed to raise the temperature, and when the temperature reaches 45: 46 ℃, the temperature will be maintained for 1.5 hours, then slowly ventilated and lowered the temperature. Pay attention to the thermometer mercury ball and the highest point of the plant at the same level when the shed is stuffy. You can also water the shed the day before, and then water it when the shed is over.

2. Medicament control: use 66.8% moldy doc wettable powder 70000x liquid, 75g Kangling 1500 times liquid, and add 300x white sugar and vinegar to control downy mildew; when mixed corner spot disease, 77% can kill wettable particulate powder 400x liquid. In recent years, a new type of agent, such as 10% Kejia suspension, whose ingredient is cyanofrozole, is a new imported drug, which is used to prevent downy mildew in cucumbers, melons and grapes. It is generally sprayed 2 times 3 times after planting slow seedlings, with 2000 times liquid, with an interval of 7 to 10 days. It can also be used as a therapeutic agent. 1000-1500 times liquid is used at the initial stage of the disease, 2 times continuously for 3 times, with an interval of 7 days to 10 days. The drug lasts for 10 to 14 days, and rainfall does not affect the efficacy 1 hour after application. It can be mixed with most pesticides and fungicides, such as 53% Jinlei 500 times solution, to increase internal absorption and conductivity.

In addition, 42% trichloroisocyanuric acid soluble powder is also promoted in recent years, which is also a new type of exterminator for the prevention and control of downy mildew in vegetables. The trade name is Kexijing. It is a broad-spectrum, internal absorption and therapeutic fungicide. Cucumber downy mildew spray with 3000-4000 times liquid, and 0.5% aminooligosaccharide water agent (Stirling) 1000 times liquid, not only cure the disease, but also improve the immunity of the plant. Spray liquid must be sprayed evenly, so that the back of the leaf with medicine, after the drug to check whether the mildew layer of leaf back disease spot is dry to death, generally should be used 2 times 3 times.