Tomato chlorovirus is an important disease in tomato production. The symptoms of the disease are very similar to those of physiology and malnutrition. Delays and preventions are often caused by misdiagnosis. Tomato leaves infected with the virus become brittle, and fruit quality and yield are reduced. The fruit is small, the taste is poor, and the commodity is declining. The virus has the characteristics of latent infestation. The seedlings sometimes have no symptoms after being infected with the virus. Symptoms do not appear until 3 weeks later, which increases the risk of the virus spreading and spreading through seedlings. At present, the virus has been in a major outbreak in Beijing, Hebei, Shandong and other regions and must be given sufficient attention. According to a survey conducted in the Shouguang planting area, most of the tomato varieties are not resistant to tomato chlorovirus, and the disease is also more endangered in the facility. The incidence of disease, field diagnosis and prevention and control measures are currently less experienced, and production needs urgently to strengthen the Viral research.

I. Field symptoms After infected with tomato chlorovirus at the seedling stage, there was a partial green spot between leaves and veins. The symptoms were not obvious and it was difficult to identify. 15 days after the colonization of tomato, if the conditions are appropriate, it can show the onset of symptoms, mainly manifested as plant diapause, short and thin, the top leaves yellow, the lower mature leaf veins slightly retreat.

The flowering period begins 40 to 50 days after the colonization of tomato, and the virus begins to show obvious symptoms in tomato. The middle and lower leaves first appeared symptoms and gradually developed upwards. The middle leaves had slight greenish yellowing between the veins. The bottom leaves showed obvious leaf degeneration and yellowing. The veins were dark green. The susceptible leaves were brittle and easily broken. The leaves were yellow and suspicious. The lack of disease.

Entering the result period, the symptoms of the virus on the tomato further exacerbated. The whole tomato of the susceptible tomato showed symptoms of chlorotic yellowing. The fruit was small and the color was white, and it could not expand normally. The leaves also showed obvious symptoms of chlorotic yellowing between the veins, the edges slightly rolled up, and red-brown small necrotic spots appeared locally. In the later period, the veins are dark green, veins are greenish and yellow, thick and brittle and easy to fold, and finally the leaves are dry and fall off; the fruits are small and begin to turn mature, causing the tomatoes to lose their commodity value, and when severe, cause the occurrence of absolute production.

Second, the incidence of the law of tomato in Shandong Province is an annual production of the crop, the virus occurred in Shandong Province anniversary. Through 3 years of investigation, it has been found that overwintering and early spring cultivation is the peak period of tomato chlorophage virus in April-May, and late autumn cultivation is the peak of tomato chlorophora virus occurrence in August-September. The temperature in April and April in Shandong Province has rapidly risen with less rainfall, making the tomato susceptible to the virus, and the climatic conditions at this stage also facilitate the propagation of virus-borne mediators Bemisia tabaci and whitefly, becoming the highest incidence of tomato chloroviruses. From June to July, rainfall increased, and the virus entered a low incidence period. From August to September, high temperatures and reduced rainfall reduced the virus into a high-transmission period. From October to March, the temperature was low and it was also low in the virus. Issue date.

Third, comprehensive prevention and control technology

1. Adjust the sowing and planting period appropriately

Affected by virus infection at the seedling stage and early flowering stage have a greater impact on yield and quality. The incidence of late infection is lighter and less harmful. Therefore, the prevention of tomato infection in the early stage is the key to disease prevention and control. Planting time should try to avoid the peak activity of whiteflies. The high temperature and dry weather conditions are favorable for the occurrence, reproduction and transmission of B. tabaci and whitefly. Therefore, according to the specific situation of each place, the timing of planting the tomato in early spring and delaying the time of late autumn tomato rinsing can be avoided. The occurrence of whitefly is of great significance for the prevention and control of the virus.

2. Strengthen field cultivation management

Strengthen cultivation and management, strengthen fertilizer and water management after planting, promote tomato plants to grow robustly, increase their resistance to disease, pay attention to ventilation, avoid high temperatures in the shed. Combine the pruning to find the diseased plants in time and remove them immediately. In addition, weeds and diseased plants are cleared in time to reduce the host plants of the whitefly.

3. Prevention and control of mediators

Physical prevention and control, nursery shed must be prepared in advance to prevent the intrusion of tomato chlorovirus, seedling stage infection tomato chlorovirus is the direct cause of tomato production, therefore, nursery shed should be separated from the planting studio, choose to stay away from pink The location of the nursery can be concentrated. The 50-60 mesh insect net can cover the entire nursery shed, or the nursery shed can be divided into different size net rooms. Pay attention to closing the entrance in a timely manner, and the yellow sticky trap board (referred to as the yellow board) will be trapped on the seedling bed. And monitor adult whitefly. The air outlets before the planting shed and the air outlets at the roof cover 50-60 mesh insect nets to prevent the invasion of whiteflies and reduce the introduction of external viruses. A certain number of yellow plates can be hung in the planting shed, which can not only alert the occurrence of the mediator but also trap and kill virus spread mediators.

4. Chemical prevention and control

The seedlings were sprayed with 10% imidacloprid wettable powder 2000 times for 3 days before transplanting to prevent the insect seedlings from moving into the greenhouse. After the planting, if sputum is found sporadically, it is necessary to spray pesticides to prevent the spread of mediators. The agents that can be used are: 25% buprofezin (Pentazoyl) WP 1500 times, 10% imidacloprid WP 2000 times Liquid, 25% thiamethoxam (Aketai) water dispersible granules 2500 times, 1.8% avermectin EC 1500 times. Spray once every 5-7 days, alternately use drugs, spraying must be done evenly when spraying. Isothermal smoke agents and other aerosols can also be used in the booth.

5. Use of plant production regulators and antiviral drugs

In the early growth stage of tomato, foliar fertilizers containing zinc, boron and calcium can be sprayed on the leaves to promote the vigorous growth of the tomato, increase the disease resistance of the plants, and reduce the damage of the tomato chlorovirus. After the tomato is infected with the virus, virucidal agents such as moroxydine hydrochloride, ribavirin (ribavirin) and phytoalexin can be used to mitigate the hazards.

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