Symptoms and Control Methods of Carrot Leaf Blight

Carrot is a vegetable with relatively high nutritional value, especially suitable for the elderly and children to eat, and its carotene content is relatively high among vegetables. In recent years, the profitability of carrot cultivation has fluctuated, but with proper management, yields are generally not a problem. However, carrots are also relatively prone to diseases, such as the common carrot leaf blight, a disease that is more likely to occur in September, especially in plants that are relatively weak in growth or under extensive management. So what are the symptoms of carrot leaf blight? How to control it?

I. What are the symptoms of carrot leaf blight?

If a carrot is affected by leaf blight, it will first show on the leaf surface, with small brown, round spots. As time goes on, they gradually spread and become large angular spots, turning light brown or grayish white, but the edges remain dark brown, and many small black dots will appear inside the spots, which are the pycnidia of leaf blight. On the hairy leaves of carrot leaves, obvious markings generally do not appear; on the hairless side the markings are more obvious, and such markings will cause the carrot leaves to slowly turn yellow until they dry up and fall off.

So where does this pathogen come from? It falls onto the ground surface and into the soil through diseased plant residues, then overwinters underground, and its seeds also carry this pathogen, all of which can transmit the leaf blight. After the pycnidia of the leaf spot pathogen absorb water, conidia gush out and spread through wind, rain and irrigation water, then invade through the leaf stomata or by penetrating the epidermis. Leaf blight reinfection is relatively frequent, so the disease develops very quickly. This is because this pathogen very much likes warm, humid environments.

II. How to control carrot leaf blight?

First, when planting carrots, good seeds must be selected, because this disease can be transmitted through seeds, so comprehensive disinfection measures should be taken before planting carrots. You can choose thiram plus new high-fat film for seed dressing; for the specific usage method, it is recommended to consult the farmers' market. This agent can drive away underground pests and diseases, reduce the occurrence of virus transmission, and will not affect its respiration, and can increase the germination rate of carrot seeds.

Second, strengthen routine field management. When planting carrots, sufficient base fertilizer must be given, and then appropriate topdressing should be applied. Usually, phosphate fertilizer and potassium fertilizer can be selected as the main fertilizers for topdressing. Water scientifically at ordinary times, and do a good job of loosening the soil after watering, so that the humidity in the field can be well controlled. After rain, drain excess accumulated water in time to avoid waterlogging and root rot and other phenomena.

Third, actively use medication to treat leaf blight. Once the disease occurs, the consequences are very serious, so pay attention to observation at ordinary times and apply medication in time to avoid infecting more plants.