In recent years, there has been a large-scale promotion of pollution-free celery in the suburbs of Ji'an City. In particular, in areas where various protection facilities are cultivated and continuously planted, spotting of celery, leaf blight, virus disease, and leaf spot disease are widespread, often leading to reduced production and quality of celery, and even to a devastating decline.
1 Severe disease symptoms
1.1 Blight
The etiological agent is the bacterium of the genus Chitosan, which is a fungus belonging to the subphylum Fungi. The main damage to the celery leaves, followed by the petiole and stem and so on. When the leaves were damaged, light brown oily spots first appeared, and then gradually expanded. The lesions showed two types. The small spot lesions were smaller, the diameter was 2-3 mm, the edges were brown, and the middle of the lesions were white. Circle yellow halo, spot on the edge of a lot of small black spots, namely conidia; large spot lesions, up to 3-10mm in diameter, lesions darker in color, the middle was grayish brown, edge Red-brown, generally no yellow halos, less black spots on the lesions. Plant leaves that were damaged by spot blight suffered from premature leaf dryness, impeded plant growth, and had poor commodity quality.
1.2 Viral disease
The pathogens are viruses such as cucumber mosaic virus, alfalfa mosaic virus, and celery macular virus. The main damage to the leaves, the early stage of the disease showed yellow and green mottled, and later brown withered. Another symptom is the presence of green, yellow, or light green ring-shaped radial lesions on the edges of diseased leaves. The edge of the lesion is obvious, and many small spots are scattered throughout the entire leaf. The damaged plants grew poorly in leaves, curled up and curled up, distorted and stopped growing, and the whole plant was short and severely reduced in yield.
1.3 Leaf spot
The pathogen is a semi-mycotic fungus. At the beginning of the onset of the disease, water-stained yellow-brown spots appeared, which gradually developed into round or irregular shapes. The spots quickly turned brown or gray-brown. The edges were yellowish-brown, slightly bulging, and the lesions expanded into pieces. Caused dead leaves. The lesions on the petioles and stems were mostly strips, brown and slightly sunken. Gray sparse mold layer appeared on the lesion under high temperature and high humidity conditions, namely the conidial stem and conidia of the pathogen. When the mold layer is washed away when water is encountered, the mold layer will soon disappear when exposed to sunlight.
2 Comprehensive prevention and control methods adopted by China Agricultural Network
2.1 Agricultural Technology Prevention and Control
2.1.1 selection of disease resistant varieties. Such as Jinnan real celery, Italian summer celery, Kaifeng glass celery and other varieties.
2.1.2 Select disease-free seeds for sowing, sowing and seed disinfection. The best use of seeds for more than 2 years, because the bacteria can only survive on the seed for 1 year, the new species to be soaked in warm water at about 48 °C for 30 minutes, and then cooled with cold water for 5-10 minutes, dried after sowing.
2.1.3 The incidence of heavy land plots should be changed over 2-3 years.
2.1.4 Strengthen cultivation management. Timely drainage and flood control, no flooding irrigation when watering; pay attention to increase the application of phosphorus and potassium fertilizers; rational dense planting, strengthen ventilation and dehumidification: timely removal of diseased leaves at the onset of the disease, remove the body of the disease to be buried or burned.
2,2 Chemical control
2.2.1 spot blight. It was sprayed with 70% mancozeb or sprayed with 75% chlorothalonil wettable powder 600 times. Greenhouses can also use 45% chlorothalonil smoke agents, Baiyue smoke and other fumigation, 667m2 greenhouses for each dose of 0.2-0.25kg. In the evening when the greenhouse is closed, the control effect is better.
2.2.2 Viral disease. In the early stage of disease, 25% of virus A600-700 times, 0.1% of zinc sulfate, 15% of virus will be WP 1000 times, 1.5% of ED 800-1000 times or 20% of leaflet enemy 600 -800 times liquid spray control, spray once every 7-10 days, even spray 3-4 times.
2.2.3 Leaf spot. At the beginning of the disease, 50% carbendazim or 75% mancozeb powder 500 times, 75% chlorothalonil 600 times sprayed, sprayed once every 10-15 days, and sprayed 2-3 times.
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