In recent years, round and leaf blight on greenhouses and cucumbers has been very serious. According to the survey, the incidence rate has reached 80%, and the severely fast disease index has reached 52.2%, resulting in the dryness of cucumber leaves, which has a great impact. The yield and quality of cucumbers have hindered the development of cucumber production. In order to improve the yield, quality and economic benefits of cucumber, we studied cucumber bacterial leaf blight from 2003 to 2005.
symptom
Mainly for the cultivation of cucumber leaves in the greenhouse. The lesions are initially dark green water-immersed, round, 10 to 30 mm in diameter, then brown, and the disease is not obvious, and some lesions have yellow halos. When the humidity is high, the surface of the lesion has a dark brown layer of mold, that is, the conidia and conidia of the pathogen.
Law of onset
The pathogens mainly overwinter in the field with mycelium and diseased bodies. When the conditions are suitable, the conidia will be produced. The air will be sprayed back onto the host plant by the airflow. When the conditions are met, the conidia will germinate, invade from the stomata, and the initial infection will occur. After 2 to 3 days of incubation, the disease leaves will be produced. Conidia are re-infected by airflow. The development of pathogens is suitable for 25~28°C, high temperature and high humidity, especially in the rainy high temperature season. Humidity is an important factor inducing this disease. In the suitable temperature range, the air humidity is high, easy to occur, and the relative humidity is 85%. Above, the temperature is about 26 ° C, and the incubation period is 2 days. In addition, the vegetable plot is damp, the cucumber grows weak, the planting is too dense, the ventilation is poor, or the fertilizer is insufficient.
In the greenhouse protection area, cucumber round blight began to occur around April 20, and peak incidence occurred in May.
Integrated control technology
1. Eliminate the source of the pathogen for more than 2 years; remove the diseased body after harvesting, burn it or bury it deeply; turn it deep in time to eliminate the initial infection; find the diseased leaves in time during field growth to eliminate the source of reinfection Can effectively reduce the occurrence of diseases.
2. Cultivate strong seedlings using the densely punctured cucumber variety, the leaf age index is 5 to 6 true leaves, the plant height is 15 to 18 cm, the seedling age is 50 days, the leaves are dark green, the foliar surface is thick, and the disease-free healthy plants are colonized.
3. Adding organic fertilizers Organic fertilizers are the basis for the growth and development of cucumbers. Provide effective nutrient for cucumber growth and development, planting in the protected area with 20×100cm plant spacing, planting 5000kg high-quality organic fertilizer and 30kg diammonium phosphate as base fertilizer before planting, and open 50cm deep ditch according to the line spacing of 100cm before planting. Apply 40cm organic fertilizer in the ditch and apply diammonium phosphate on the organic fertilizer.
4, timely leaf surface topdressing cucumber round leaf blight prevention and control can only be effective to improve the plant's own disease resistance mechanism. After the plant is slowed down, 300 times of potassium dihydrogen phosphate is sprayed on the cucumber leaves every 7 days, so that the various organs of the cucumber can fully absorb the nutrients, ensure the nutrients needed for the growth and development of the plants, and thicken the leaves of the cucumbers. To inhibit the invasion of pathogenic bacteria; formula fertilization technology can also be used to spray 4,000 times solution of multi-effect solution or 7000 times solution of 1.4% sodium nitrite solution to improve the disease resistance of plants and effectively control the occurrence of round blight. popular.
5, the use of ground topdressing plants during the growth of organic fertilizers and inorganic fertilizers in the ratio of 2:1, the two are indispensable, after the harvest of the roots every 10 days per mu with water 20mL urea or ammonium sulfate water When cucumber grows 30 to 35 leaves, the heart is topped. When the heart is picked, 20 kg of decomposed soybeans are applied to ensure sufficient supply of various nutrients, which enhances the disease resistance of cucumber and improves the yield of cucumber.
6. Timely irrigation water is an essential condition for plant growth, which is the basis of cucumber growth and development. It lacks water, plants grow slowly, leaves become smaller, fruit is deformed, directly affects yield and output value. After ditching and filling small water, it can be “clearly poured, not poured, poured in the morning, not poured in the afternoonâ€. After the water has been infiltrated, it will be restored to its original position. After the cucumber plants are full, the ditch will be filled with water, and the soil in the ditch will be planted near the rhizosphere of the plant. The water will be poured once every 5 days, and timely cultivation will be beneficial to the cucumber. Growing.
Chemical control
(1) Fumigation fumigation kills pathogens If there is a long-term rainy weather, the indoor air humidity is relatively high, and the smoke method is more suitable. It is best to do it at night. 250g of porphyric acid clearing agent was placed in 5 places, ignited with a dark fire, closed at the time of smoking, and exposed in the morning on the second day. Once every 10 days, even smoke 3 times.
(2) Using high-efficiency, low-toxicity and low-residue pesticides to prevent and control the early spraying of the disease, spraying 27% copper high suspending agent 600 times liquid, 77% killing wettable powder 400-500 times liquid, 1: 1: 200 times Liquid Bordeaux mixture, 50% mixed sulfur suspension 500 times solution, 50% polysulfide suspension or 50% thiophanate-methyl WP 800 times solution, 60% anti-mildew ultra-wet WP 800 times solution, Once every 10 days or so, continuous control 2 to 3 times. Note that two or more drugs are used in rotation to delay the development of drug resistance, and the drug is stopped 3 days before harvesting.
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