Tomatoes, as the most widely cultivated and popular vegetable crop in the world, may be attacked by a variety of diseases throughout their growth cycle, which can seriously affect yield and quality. These diseases have a wide variety of forms and different forms, causing varying degrees of damage to the growth and development of tomatoes. The following will provide an in-depth analysis of several common tomato diseases and their prevention and control methods.
First of all, early blight, also known as brown spot, is a common fungal disease in the early growth period of tomatoes. In the early stages, round or near-round brown lesions appear on the leaves, and as the disease progresses, the lesions** turn grayish-white and the edges appear blackish-brown. For the prevention and control of early blight, the primary strategy is to choose disease-resistant varieties to fundamentally reduce the possibility of disease occurrence. In addition, it is important to have a proper crop rotation system to avoid continuous planting of tomatoes and solanaceae crops to avoid the accumulation of large amounts of pathogenic bacteria in the soil. The strengthening of field management should not be neglected, such as timely removal of diseased residues and scientific fertilization to improve the disease resistance of plants. In the early stage of the disease, high-efficiency fungicides such as carbendazim and thiophanate-methyl can be sprayed for chemical control.
Secondly, late blight mainly harms the leaves and fruits of tomatoes, and the initial symptoms are water-stained dark green lesions, and when the humidity is high, a white mold layer can even be seen on the surface of the lesions. For the prevention and control of late blight, it is also necessary to give priority to the selection of disease-resistant varieties, and reasonably control the planting density, ensure the ventilation and light transmission conditions in the field, and reduce the breeding environment of diseases. Once the diseased plant is found, it should be removed in time and sprayed with agents such as silver farry, frosturea, manganese zinc and other agents to prevent the further spread of the disease.
Leaf mildew is characterized by the formation of gray to purplish-brown mold layer on the back of the leaf and yellowing and green patches on the front. The key to the prevention and control of leaf mold is to select disease-resistant varieties and plant them appropriately to improve ventilation conditions and inhibit the reproduction of pathogens. When the initial symptoms of the disease are found, action should be taken quickly to spray and control with pesticides such as azoxystrobin and flusilazole.
In addition, gray mold mainly affects flowers, fruits and leaves, and gray-brown mold layer can be seen in the diseased part, especially in humid environment. In this regard, we need to avoid excessive humidity in the shed through reasonable dense planting, and at the same time use plastic film mulching to reduce soil moisture evaporation, and pay attention to strengthening ventilation and moisture drainage during the flowering and fruiting period. Once the disease occurs, it can be effectively prevented and treated with drugs such as pyrimide and pyrimethylamine in the early stage.
As for viral diseases, they mainly include mosaic virus disease, stripe virus disease, etc., and the diseased plants show symptoms such as leaf deformation, mosaic and leaf shrinkage. The prevention and control of viral diseases should start from the source, select disease-resistant varieties, eliminate viruses - aphids and other insects, and strictly plant quarantine to prevent the introduction of diseased seedlings into the field. When a diseased strain is found, it must be uprooted and destroyed immediately to prevent the spread of the disease.
Finally, wilt (bacterial wilt) is a devastating soil-borne disease in which diseased plants tend to wilt rapidly in a short period of time until they die, and the vascular bundles of rhizomes turn brown. To prevent and control Fusarium wilt, a strict crop rotation system should be implemented to prevent continuous cropping with Solanaceae cropsChoose disease-free seeds and soil, and use pesticides such as chlormetyl and dixone to dress seeds or disinfect soil before sowingIn the early stage of the disease, chlorobromoisocyanuric acid, copper ammonia and other agents can be applied by root irrigation**.
The various disease control measures mentioned above need to be applied flexibly according to local climatic conditions, soil conditions and regulations on the use of pesticides. In fact, we advocate the concept of comprehensive prevention and control, that is, the integration of improved breeding, agricultural control, biological control and other means to form a comprehensive and systematic prevention and control system, in order to minimize the occurrence and spread of various diseases, ensure the healthy development of the tomato industry, and provide more high-quality tomato products for human beings.