Pollution-free prevention and control of pepper blight

Symptoms of damage in the field

The incidence peak of sweet (hot) pepper blight cultivated in open field is from the middle of July to the end of August, which is a fungal disease, and the incidence rate of vegetable field is more than 85%. The pathogen has a short incubation period, rapid infection and rapid spread. if it is light, it will reduce production by 30%. In severe cases, it will die in a large area, with a dead plant rate of 20% to 80%, or even no production, resulting in devastating disasters. Symptoms: there are obvious central diseased plants in the disease area, the plant wilted at the initial stage of the disease, the leaves and fruits did not fall off, and did not change color. Careful observation showed that the base of the stem of the plant turned brown in a week, even constricted. In severe cases, the upper stems, leaves and fruits are infected, and when the humidity is high, the fruit produces a white mildew layer, which still hangs on the branches after drying and wrinkling. After the leaves were seriously infected, the dark green watery spot expanded rapidly and the soft rot became light brown after drying, and the fruit leaves were easy to fall off at this time. The stem is easy to occur first in some branches of the root, and the cortex softens and decays easily when it is serious.

Second, the cause of the disease

1. Climatic conditions are the decisive factors for the occurrence and epidemic of epidemic diseases. When the air temperature is suitable, the average daytime temperature is 25 ℃ and the night temperature is 11 ℃. It is cloudy and rainy or foggy or dewy for many days, and the field is hot and humid. Sweet (spicy) pepper blight is easy to occur and spread rapidly, resulting in a pandemic.

two。 The resistance of varieties is poor.

3. Seeds or seedlings carry bacteria. Seeds or seedlings with pathogenic bacteria are the main sources of primary infection. After transplanting diseased seedlings, the pathogen spreads to other plants with the help of soil water. Other plants can also be infected by tillage and Rain Water to form central diseased plants and expand infection to nearby plants.

4. The continuous stubble is serious. Continuous cropping will cause the pathogens overwintering in the soil and the disease residue to continue to infect the pepper body in the second year.

5. Improper selection of parcels. The land with low-lying terrain, poor drainage and heavy soil viscosity is conducive to the occurrence and epidemic of the disease.

6. Improper cultivation and management. Partial application of nitrogen fertilizer, high planting density, poor soil preparation quality, untimely ploughing, serious grass shortage, weak seedling growth, flood irrigation, stagnant water in the field and no timely prevention are also important factors of the disease.

III. Pollution-free prevention and control

Carrying out the policy of "prevention first, comprehensive control" to control sweet (spicy) pepper diseases, insect pests and weeds is a key strategy for pollution-free vegetable production. In comprehensive control, we should take agricultural control as the basis, take measures according to time and local conditions, and make rational use of chemical control, biological control, physical control and other measures.

(1) Agricultural prevention and control

1. Choose disease-resistant varieties. Under the premise of selecting marketable and suitable local varieties, varieties with high yield, high quality, disease and insect resistance and strong stress resistance should be planted. For example, red sweet pepper No. 1 and red pepper king are resistant to blight and Fusarium wilt, but the resistant varieties are less resistant to downy mildew and powdery mildew.

two。 Choose the right place. Select the plot with good regional ecology, far away from pollution sources, clean air and irrigation water, convenient drainage and irrigation, deep, loose and fertile loam or sandy loam, pH 6.0-7.5. The previous stubble is turned over in autumn for wheat and bean stubble or corn stubble. The previous crop should not be selected as eggplant fruit, potato and melon crop plots, and special attention should be paid to avoid the plots where the residual pesticides were used too long last year.

3. Cultivate disease-free and strong seedlings. (1) seed disinfection: soak the seeds in 52 ℃ warm water for 15 minutes, or pour 1 kg of seeds into 98% concentrated sulfuric acid 80 ml and stir thoroughly for 5 minutes for 6 minutes. After rinsing with clean water, soak for 4-8 hours to accelerate germination and sow seeds. (2) raising seedlings in disease-free soil: select fertile soil that has not planted eggplant fruits, melons and potatoes, and mix fully mature farm manure as seedling soil to cultivate disease-free seedlings. (3) medicament treatment of seedbed soil: 1 gram of Luheng No. 1 and 50% Fumishuang 5 grams of fine soil were mixed well with 20 kg of fine soil per square meter, then 1 beat 3 was sprinkled on the border surface, and the remaining 2 prime 3 was used as sowing cover soil. (4) after emergence, the seedbed was sprayed with 40% ethyl phosphate aluminum 300 times solution or 25% pyrethromycin 800 times solution, and 50% nail cream copper 500 times solution was sprayed twice 10 days before transplanting, which can prevent bacteria from entering the field.

4. Improve cultivation measures and strengthen field management. (1) turning the ground in autumn with a depth of 18cm and 22cm, leveling and raking fine. (2) to apply fertilizer scientifically, the fertilizer requirement of sweet (hot) pepper is potassium ≥ nitrogen > phosphorus. For every 1000 kilograms of commercial pepper, 3.54kg of nitrogen, 1.03kg of phosphorus pentoxide and 3.38kg of potassium oxide are needed. Take high-quality farm manure as the base fertilizer, increase the application of potash fertilizer, timely topdressing to promote seedling and attack fruit fertilizer, pay attention to the use of micro-fertilizer. (3) High ridge cultivation covered with plastic film. (4) strengthen field management, plough deeply and kill weeds in time, enhance pepper resistance, remove diseased plants in time and take them out of the field for destruction, and sterilize the diseased holes with quicklime. (5) to master the cultivation characteristics of the cultivated varieties and achieve the improved varieties and methods.

(2) Chemical control

1. Focus on prevention, that is, spraying with protective agents before the occurrence of the disease, focusing on the base of the rhizome. It is recommended to use 600 × 800 times of green milk copper, sprayed for 2 times for 3 times, which has both protective and therapeutic effects, which can basically ensure that the disease will not occur.

two。 The disease field can be sprayed with imported Prik 500 times, or 64% antiseptic alum 400 times solution, or 58% Ruidu mold manganese zinc 500 times solution, or 25% ethyl phosphorus aluminum 300 times solution, cross-administered to prevent bacteria from developing drug resistance.

3. To master the pesticide safety interval, it is forbidden to use medicine 8-10 days before fruit harvest in summer and autumn, or commercial pepper is not harvested until 10 days after drug use.