The viral disease of zucchini has become an important disease in production in recent years. According to surveys in Xiangshui and surrounding areas, the average incidence rate of zucchini virus disease is more than 25%, a few sheds reach 100%, and the incidence of field blocks can reduce production by about 30%, and the income of vegetable farmers is greatly reduced. To this end, according to the results of recent surveys and studies, and with reference to relevant information, analysis and sort out the comprehensive prevention and treatment technology of the zucchini virus disease for reference.
1 Symptoms, Pathogens, Pathways and Conditions of Squash Virus Disease
1.1 symptoms
The main symptoms of zucchini virus disease are yellow, floral and fern leaves. Yellowing plants are thin, yellow leaves become smaller, new stems tend to be finely twisted, and the apex of the plant is shortened between nodes, and the flower is small and does not stretch. In the initial stage of the mosaic type, green mosaic spots appeared on the top leaves, and the mosaic spots of dark green and light green were seen everywhere on the leaves. The leaves were uneven, the leaves were small and shrunken, and the internodes of the leaves became shorter. The fern leaf type shows a new leaf that is long and narrow, shrinking and twisting, slow growth, thin and small plants, and sometimes the parietal leaves do not grow in clusters. The incidence of fruit before flowering, poor flower development, difficult to set fruit. After onset of fruit set, fruit development is not good, easy to form deformed fruit, serious fruit is small, uneven surface, low yield, poor product rate.
1.2 Pathogens and routes of transmission
According to studies, the squash virus disease is mainly caused by the infection of cucumber mosaic virus (CMV), watermelon mosaic virus (WMV), and pumpkin mosaic virus (SqMV). The virus spreads mainly through seeds, while insects and spurs pass infections and sap to contaminate insects. Cleanup of diseased leaves, pollination, fruit picking and other agricultural activities in the fields are also one of the routes of infection.
1.3 Incidence conditions
High temperature and drought are the main conditions of the disease. Before the greenhouse, cucumbers, melons, and other crops, or adjacent to the melon crops, intercropping are also susceptible to disease; squash in the greenhouse lack of fat, extensive management, weak growth of the plants are often more severe. Virus disease in summer can occur in greenhouses. It occurs mildly in winter and spring, and is severe in summer and autumn. Viral diseases often show symptoms when plants enter the flowering stage. At this time, the disease often causes irreparable damage.
2 Integrated control of virus disease in greenhouses
2.1 Selection of disease-resistant varieties
At present, there are few varieties of squash that are cultivated in China. According to the survey, the early-generation cultivars are more resistant to viral diseases.
2.2 Seed disinfection
After sunny day at 10-15 o'clock in the afternoon, soak the seeds with warm water of 55°C for 15 minutes (minutes), remove them and soak them with 1% potassium permanganate solution for 20 minutes, or soak them with 10% trisodium phosphate solution for 15 minutes. Wash out and dry to sow.
2.3 Pay attention to mouth arrangement
The zucchini should not be planted in the shed where the melons are planted in the front rakes. The sheds should not be interspersed and be used as other melon crops.
2.4 Implementation of High Temperature
About 15 days before transplanting the cucurbit planting sheds, the sheds were covered with plastic film, and the sheds were sealed to increase the toxic temperature of the virus in the shed as much as 60° C. to kill the poison source in the sheds. It is important to worry about greenhouse crops.
2.5 Shade net nursery
Autumn delay in the cultivation of zucchini, nursery when the best use of silver-gray shade net cover, both anti-high temperature, moisture, but also to prevent locusts and keep melon harm.
2.6 Pay attention to pest control
Due to the high temperature inside the shed, the growth and development cycle of locusts and slugs is short, the generation overlaps severely, pests are often fierce, and should be completely controlled from the seedling stage. The medicine can be selected with 20% chrysanthemum cream 1500 times, or 25% anti-mite. 2500 times solution or 40% dimethoate 1000 times solution can be used alternately. The silver-gray mulching is used for planting until it avoids the effect of embarrassment.
2.7 Strengthen Water Management
For each 667m2 greenhouse, 5,000 kg of organic fertilizer with good quality and 50 kg of phosphate fertilizer were used as base fertilizer. Applying nitrogenous fertilizers at seedling stage and increasing phosphorus and potassium fertilizers can increase the disease resistance of plants. When the plants enter the flower budding stage, combined with spraying, foliar spraying of Huimanfeng and other foliar fertilizers to promote growth, increase plant anti-virus capacity; and pay attention to proper watering, increase soil moisture. When the initial symptoms appear in the plants, the application of nitrogenous fertilizers should be increased.
2.8 Prevent contact infection
When carrying out agricultural operations in the shed, it is best to use a 0.5% potassium permanganate solution to disinfect the cutters used for harvesting fruit from the healthy plants and the diseased plants. Do not knock or trample the stems and leaves to prevent transmission of diseases. Individual plants can be removed at the time of onset to control the source of infection.
2.9 Chemical Control
In the early stage of disease, 20% virus A wettable powder 400 times liquid or NS83 virus resistance inducer 60 times liquid spray, or spray 1.5% epidemiological emulsion 800 times, spraying once every 7 days, continuous prevention and treatment 2-3 times In addition, spraying 1000 times potassium permanganate also has a certain control effect.
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