When it comes to foods rich in dietary fiber, people often first think of celery. Celery is the most common green vegetable in our daily life, containing a large amount of protein, carbohydrates, fat, fiber, and various vitamins and minerals. It is an essential and delicious dish on the dining table of the common people. If planted improperly, diseases can occur. Like spot blight: Celery spot blight, also known as leaf blight, is widely distributed and can continue to occur during storage and transportation. At present, this disease has become an important disease of celery in winter and spring protected areas, which has a significant impact on yield and quality. Below is an explanation of the symptoms and prevention methods of celery spot blight:

1、 Symptoms

Celery spot blight mainly affects leaves, followed by petioles and stems. At the beginning, the disease spot on the leaf is a light brown oil stain like small spot. After enlargement, the outer edge of the disease spot is yellow brown, and the middle is yellow white to gray white, with obvious edges. There are many black small particles (conidia) on the disease spot, and there is often a yellow halo outside the disease spot. On the petiole and stem, the diseased spots are oblong, slightly concave, with obvious edges, brown, and light internal color. The spots are densely covered with obvious black granules.

2、 Prevention and control methods

1. Selecting disease-free seeds, collecting seeds from disease-free plants, or using aged seeds that have been around for more than 2 years, can have certain disease prevention effects.

2. If new seeds that have been stored for less than 1 year are used for seed disinfection, they must be disinfected. When disinfecting, warm water at 48-49 ℃ can be used to soak the seeds for 30 minutes. During soaking, stirring should be kept continuously. After soaking, cold water should be immediately poured into the water to cool down, and then air drying or germination sowing should be carried out. This method reduces the germination rate by about 10% after soaking the seeds.

3. Eliminate diseased residues in the field and rotate the affected areas for 2-3 years. Remove diseased leaves in the early stages of the disease. Disease residues in the field should be concentrated and composted or deeply buried.

4. Chemical prevention and control: When the height of celery seedlings is 2-3 centimeters, spraying should be started for protection, and spraying should be done every 7-10 days thereafter. Medications can be selected: 75% chlorothalonil wettable powder in 500-800 times the liquid, and 65% mancozeb wettable powder in 500 times the liquid; 50% Daisen ammonium 1000 times solution; 1: 0.5:200 Bordeaux liquid.

5. Strengthening cultivation management: Improving cultivation techniques can effectively control the occurrence and harm of diseases.

(1) Arrange sowing to avoid the disease period, changing the traditional method of sowing in spring and harvesting by splitting leaves in stages within the year to a method of arranging sowing and harvesting by stages to avoid the disease period. Early celery seedlings are raised in March, planted in mid April, and harvested in early June; The second crop of celery is sown in mid April and harvested in early July; The celery is sown before the fall and harvested in September. In this way, during the epidemic period of spot blight in July and August, early celery and second crop celery have already been harvested, while dormant celery seedlings are small, which is conducive to avoiding harm through field management.

(2) Select cultivation sites and control temperature and humidity. According to the characteristics of celery, which prefers to be warm and cool, but not scorching hot, and prefers to be moist and not dry, celery is planted in a cool black soil area. It is irrigated with small water every 3 days to control field temperature and humidity, reduce the harm of spot blight, and achieve a high yield of 13000 kilograms per acre.

(3) After applying sufficient base fertilizer, the early celery should be continuously watered with fecal water 3-4 times due to the low temperature in the cool weather. The seedlings should be about one foot tall before being watered with clean water; The second crop of celery is mainly treated with ammonium sulfate, followed by fecal water; Fu celery and autumn celery are topdressing with ammonium sulfate and water. If encountering heavy rain, scorching sun exposure, or improper management, which can easily lead to spot blight, it is necessary to promptly drain the field rainwater, irrigate with clean water, and apply more ammonium sulfate instead of fecal water.

(4) Plant densely and seedlings in a timely manner. Overdense planting or untimely removal of seedlings often leads to poor ventilation, high humidity between plants, and susceptibility to disease. The density should be 10-15 centimeters between rows, 10-15 centimeters between holes, and 6-10 plants per hole.