The pathogens of zucchini virus disease are pumpkin mosaic virus, tobacco ring spot virus, watermelon mosaic virus, cucumber mosaic virus and melon mosaic virus. Among them, the most important pathogens are cucumber mosaic virus and melon mosaic virus. There are many hosts and transmission routes of these viruses, which will lead to the large-scale occurrence of zucchini virus diseases.

1 The seeds themselves carry virus

If the seeds of zucchini are sowed directly without disinfection before sowing, the seeds themselves are very likely to carry virus and become the primary infection source of zucchini virus disease.

.2 There are viruses in fertilizers and soil

Modern agriculture advocates using less chemical fertilizers and more farmyard manure. However, when using farmyard manure, if the manure is applied blindly, it may carry the virus and infect the zucchini plants with the application of fertilizer. If zucchini is planted in the plot where virus disease occurred last year, and the plot is not sterilized before planting, there will be residual diseased plants in the soil from last year, and the viruses on these diseased plants will continue to infect new plants after finding new hosts.

3 insect transmission

A large part of the spread of zucchini virus disease is due to the intervention of aphids and whitefly. Through their flight, the pathogen of zucchini virus disease can be transmitted to healthy plants, resulting in a large-scale occurrence of zucchini virus disease, especially in dry, rainy and high temperature seasons, aphids and whitefly will multiply in large numbers, and virus diseases will also break out in a large area.

.4 Artificial transmission

The whole cultivation process of zucchini needs manual treatment. During the processes of tying vines, pruning, raking, dipping flowers and field management, viruses will be contaminated on operators and spread to other plants as they move, resulting in a large-scale occurrence of virus diseases.

prevention and control methods

.1 seed treatment before sowing

before sowing, the seeds of zucchini should be disinfected and germinated to prevent the seeds from being infected and becoming the primary source of infection. Specific operation process: firstly, soak the seeds in clean water, then soak them in 1% trisodium phosphate solution for 3 min after 4 h, then rinse the seeds with clean water and dry them in the air, and put them in a sterilized wet cloth, and after a period of time, the seeds will sprout.

2 Selecting resistant (tolerant) varieties

Planting resistant (tolerant) varieties is the most effective way to prevent and treat virus diseases. Only by improving the resistance (tolerance) of plants themselves, the losses caused by virus diseases will be lighter. At present, the varieties with strong disease resistance circulating in the market mainly include Zaoyu, Golden Coral, Xuehu No.1, Jasper, Dongyu, etc. These varieties not only have certain resistance (tolerance), but also have high yield and good comprehensive benefits, which can be popularized and cultivated in a large area.

.3 Strengthening field management

The zucchini planting field can be rotated with Gramineae crops, and it is forbidden to plant zucchini in the same field for years to prevent cross-infection of virus diseases and depletion of soil nutrients. Before sowing, the soil should be prepared, and the soil should be deeply ploughed, and the ploughing depth is generally about 1 cm. Applying sufficient base fertilizer can cultivate strong seedlings and strengthen the disease resistance of plants. It is necessary to regularly clean up the planting fields to reduce the number of other hosts of the virus and the living space of aphids, whiteflies and other insect vectors. Temperature management should be strengthened after the summer squash is planted. When the temperature is too high, water can be sprayed appropriately to reduce the temperature of the field. When the soil moisture content is high, the amount of nitrogen fertilizer should be reduced appropriately; After the zucchini bears fruit, the temperature should be raised appropriately, and the temperature should be kept at 25? 3℃ is conducive to the synthesis of organic substances, and the temperature should be appropriately reduced at night, and the general temperature should be kept at 15? 18 ℃。 When a diseased plant is found, it should be pulled out and burned or buried in time to prevent the pathogen from spreading to other healthy plants and causing the spread of the disease.

.4 spraying chemicals

at present, chemical control is the most common, and spraying chemicals has three main functions: one is to kill the vectors of diseases such as aphids and whiteflies and prevent the spread of diseases; The second is to kill the pathogen of zucchini virus disease and reduce the symptoms of the disease; The third is to enhance the disease resistance of plants. Pesticides for killing aphids and whiteflies should be sprayed as soon as possible. After the zucchini is planted, pesticides can be sprayed on the surface and around the field. Aketai water dispersible granules are generally used, and water should be diluted when used. In addition, 5% pymetrozine has a good insecticidal effect. Pesticides to kill virus pathogens should be sprayed in time, otherwise the effect will not be good. At the early stage of the disease, before the disease has spread in a large area, 5 times of 2% virus A wettable powder or 8 times of 1.5% Zhi Bing Ling EC should be used to spray the diseased plants, once a week and continuously for 3 times. Four weeks can effectively kill the virus and relieve the symptoms of the disease. To improve the disease resistance of zucchini plants, 7 5 times of phytoalexin solution or 6 times of Aiduo solution can be sprayed on all zucchini plants at the early stage of the disease to enhance their disease resistance.

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