First, the symptoms
The seedlings are infected, yellow-white round spots on the cotyledons, and the whole leaves are dry after development; the stems are infected with water-soaked dark green fusiform spots, which are cracked and cracked, and the black mold layer grows when the humidity is large; The growth point is infected for 2 to 3 days, and the heartless seedlings are rotted into bald piles; the diseased leaves begin to produce chlorotic spots, which are nearly round, gradually enlarge and quickly dry up, forming round or nearly round yellow-white large lesions, disease After the perforation of the spot leaves a star-like edge, the periorbital leaves shrink; the dark green depression on the melon strip, the surface grows black mold layer, the lesion appears as a scab, stops growing, and forms a deformed melon.
Second, the conditions
The optimal temperature for onset is 20 ° C to 22 ° C, and the relative humidity is 90% or more. Therefore, even cloudy days, insufficient light, plant stagnation, excessive humidity, long-term heavy sputum and sowing of diseased seeds are important conditions for the onset of disease.
Third, prevention and treatment methods
1. Rotation. Rotating with non-cucurbitaceae vegetables for 2 to 3 years.
2. Use disease-free seeds and seed treatment. In addition to selecting resistant varieties, it is also necessary to use disease-free seeds. The diseased seeds need to be disinfected. They can be soaked in warm water at 50 °C for 30 minutes, and then taken out and cooled to germination. It can also be seeded with 50% carbendazim or captan WP which is 0.4% by weight of the seed.
3. The greenhouse uses sulphur powder to smoke. Before planting or nursery in the greenhouse, turn the ground, use 2.4 grams of sulfur per cubic meter of space, add 4.5 grams of sawdust and mix well, and then ignite the closed smoke for 1 night. After 7 to 10 days, seedlings or colonization can effectively kill the bacteria.
4. Strengthen greenhouse management to prevent disease from occurring. In the production period, flooding of large water is strictly forbidden, and dehumidification should be carried out by means of warming and dehumidification and high-temperature air release. The specific method is: after the scorpion is exposed every morning, the humidity in the shed can reach 90% to 100%. At this time, ventilation and moisture can not be taken. One of the reasons is that the greenhouse cucumber growth period must be 28 ° C ~ 33 ° C every morning is the most suitable high-yield temperature, the early release of low temperature is not conducive to high yield of cucumber; the second reason is that the indoor humidity can be reduced by 1 ° C 2% to 3%. Therefore, in the morning, when the temperature is low and the air is dehumidified, it is worse than the effect of warming and dehumidifying. Therefore, the correct way is to not release the wind immediately after the morning is revealed. It should be to close all the air outlets and let them warm up to 33 °C ~ 35 °C and then suddenly open the top air outlet for air release and dehumidification. However, when the temperature drops to 30 °C, the air vent is closed again, and when it exceeds 33 °C, the air is released. Every morning, 2 to 3 times of high temperature release, and in the afternoon, the temperature is reduced to 25 ° C ~ 28 ° C. This will greatly reduce the humidity, especially the nighttime humidity, and effectively control the occurrence of black spot disease and various diseases.
5. Drug control. When a diseased plant is found in the shed (the diseased seedling should be removed in time), 45% chlorothalonil aerosol should be used immediately for 1 time, and 40% DuPont Fuxing 8000 times spray or 50% chlorhexidine WP can be used. 1000 times liquid leaf spray, once every 7 days, pay attention to the use of drugs can get better results.
Steel elbows:
1. O. D: Seamless: From 1/2' up to 24' DN15-DN600;
Welded: From 26'up to 80' DN650-DN2000
2. W. T: SCH10, SCH20, SCH30, SCH40, STD, SCH80, XS, SCH120, SCH160, XXS
3. Material of Steel elbows: A234-WPB, A420-WPL6, A234-WP11, A234-WP5, A403-WP304, A403-WP304L, A403-WP316, A403-WP316L, SS304, SS304L, SS316, SS316L
5. Application Standard: ASTMB16.9, ASTM16.11ASTMB16.28, JISB2311/2220 DIN2617/2616/2615/2391 6. Connection: Hot formed, cold draw, welded
7. Types: Seamless and welded, LR & SR
8. End: Bevel, Plain, Thread, Socket
9. Steel elbows Surface Treatment:
1) sandblasting
2) paint black lacquer or transparent oil on surface to prevent corrosion.
10. Packing:
1) Seaworthy wooden box for fittings with size from 1/2" ~ 14"
2) Seaworthy wooden pallet for fittings with size above 14"
3) According to the packing requirement of clients
11. Steel elbows Capacity:
(1) 1000 tons/month pipe fittings.
(2) We always have a great stock of products in warehouse, which will help us to shorten delivery time once we confirming orders with clients.
We have adopted advanced production equipment and technologies to manufacture our Steel elbows, tees ,pipe caps, pipe bend Blind Flanges ,socket pipe union and seamless steel, which can not only improve product quality, but also save raw materials. Our products have high strength, good toughness and resistance to corrosion.
90 Degree Elbows,45 Degree Elbows,Long Radius Elbows,Short Radius Elbows
Cangzhou Fixed Star Steel Co.,Ltd , http://www.fixedstarpipe.com