Prevention and control of celery spot blight in protective field
The celery spot blotch, also known as late blight, leaf blight, commonly known as fire dragon. The disease is distributed all over the country. In particular, the occurrence of celery in protected areas is more important than open field. It is an important disease of celery in winter and spring protected areas, and has a great impact on the yield and quality. It can continue to be damaged during the storage, transportation, and sale period after harvest.
First, the symptoms
The main damage to the leaves, followed by harm to the stems and petioles. Leaf damage, I mainly to small spots, lesions at the beginning of the oil immersed small spots, gradually expanded after the center of necrosis, late lesions more than no more than 3 mm, usually 0.5 to 2 mm, constant joint, middle yellow White, the edge is clearly yellow-brown, yellow halo around the lesion often, dense black spots in the center of the lesion. The lesions on petiole and stem were oblong, slightly sunken, slightly darker in color and scattered with black dots. Severe dry leaves and stems.
Second, the incidence of the law
The spotting of celery leaf spot is a fungal disease. The pathogenic bacteria mainly live in the seed coat or with the diseased body over the winter, and can live on them for 1 to 2 years. Through the spread of wind and rain, farm implements and agricultural activities can also be spread. Long-distance spread by seeds with bacteria. Low temperature and high humidity are conducive to the disease. The most suitable temperature of the disease is 20°C～25°C and the humidity is above 95%. In deep winter season, even cloudy days, frequent temperature fluctuations or daytime heat, nighttime condensation, Poor plant growth, irrigation, lack of timely ventilation and other factors can often lead to the rapid spread of the disease.
Third, disease control
1. Use resistant varieties. Choose the more resistant or disease-resistant varieties that are suitable for local cultivation, such as Celery 3, Jinqin, Dongqin, Jinnan Real-Qin.
2. Use sterile seeds or seeds for disinfection. Planted from disease-free plants. Seeds should be sterilized. When sterilized, they can be soaked in warm water of 48°C～49°C for 30 minutes, evenly stirred, and then immediately moved into cold water to cool, and then air dry the seeds.
3. Strengthen cultivation management. Strengthen the management of fertilizers and waters, apply basic fertilizers, apply fertilizers in time, and prevent fertilizer shortages. Do not flood irrigation, remove water after rain. Protected cultivation should pay attention to ventilation and dehumidification, to meet the celery Xiliang afraid of hot, hi moist afraid of dry growth requirements. During the day, the temperature is controlled between 15°C and 20°C. If the temperature is higher than 20°C, release the air in a timely manner. At night, the temperature should be controlled between 10°C and 15°C to reduce the temperature difference between day and night and reduce condensation. At the early stage of disease, the diseased leaves and the bottom stems and leaves should be removed in time, and after the harvest, the debris should be removed and deep-turned. Seriously implement 2 to 3 years of rotation.
4. Chemical control. With 45% of the chlorothalonil smoke agent or acetaminophen smoked shed, 150 grams per acre dispersed 5 to 6 lit, fumigation overnight, once every 10 days. Spray 70% of mancozeb WP 600 times or 50% carbendazim WP 600 to 800 times or 85% of Trichloroisocyanuric Acid Soluble Powder 1000 to 1500 times, every 7~ 10 times a day, continuous spray 2 to 3 times have a good preventive and therapeutic effect.