Cucumber anthracnose disease can be triggered from the seedling stage to the adult stage of cucumber. The seedlings are affected, and semi-elliptical brown spots appear on the edge of the cotyledons. The orange-yellow point-like gums are formed, that is, the conidia discs and sub-points of the pathogens. Spores. The base of the stems of the heavy seedlings became yellowish brown and gradually shrunk, causing the seedlings to collapse. The lesions on the leaves are nearly round, with a diameter of 4 to 18 mm. The humidity in the greenhouse is large, and the lesions are light gray to reddish brown, slightly moist, and the leaves are dry.
Symptoms often have different phenotypes under high or low temperature conditions and are easily confused with leaf spot. The lesions on the main vine and petiole are elliptical, yellow-brown, slightly concave. In severe cases, the lesions are connected and surround the main vine, causing some or all of the plants to die. Melon strip disease, the lesion is nearly round, initially pale green, followed by yellow-brown, or dark brown, the diseased part is slightly sunken, the surface has pink sticky, often cracked later. Amber flow glue sometimes appears on petiole or melon strips.
Law of onset
Cucumber anthracnose mainly lives on the seeds with mycelium or sclerotia, or overwinter in the field with diseased plants, and can also survive on old wood in greenhouse or plastic greenhouse. The pathogen after wintering produces a large number of conidia and becomes the source of initial infection. In addition, the mycelium that is latent on the seed can also directly invade the cotyledon, leading to the onset of seedling stage. The conidia of the pathogen spread through the rainwater, the spore germination is moderately 22~27°C, the growth of the pathogen is 24°C, and the growth stops below 8°C below 30°C. 10 ~ 30 ° C can be ill, of which 24 ° C incidence. Humidity is an important factor inducing this disease. In the suitable temperature range, the air humidity is high, easy to onset, the relative humidity is 87% to 98%, the temperature is 24 °C, the incubation period is 3 days, and the relative humidity is less than 54%.
In the early spring, the plastic shed has low temperature, high humidity, a large number of water droplets on the leaf surface, cucumber spitting water or leaf surface condensation, and the humidity condition of the disease is often in a state of satisfaction and is popular.
In the open field, the disease is different. The south is from May to June, and the north is from July to September. It is easy to occur under low temperature and rainy conditions. The temperature is over 30%, the relative humidity is lower than 60%, and the disease develops slowly. In addition, the use of non-expanding cultivation methods and continuous cropping, excessive nitrogen fertilizer, flood irrigation, poor ventilation, and plant weakness are severe.
Control method
(1) Select resistant varieties. Such as Jinyan No. 4, Protected Area No. 1, Protected Area No. 2, 9206, Early Qing No. 2, Zhongnong 1101, Xiafeng No. 1. In addition, Zhongnong No. 5 and Xia Qing No. 2 are more resistant to disease. Use disease-free seeds to keep seeds from disease-free melons, soak seeds for 50 minutes at 50-51 °C for 20 minutes, or 50 mL for 10% fluroxycazole suspension for 50 kg seeds, diluted with 0.25-0.5 kg water. Evenly mix the seeds after the liquid medicine, and then germination or live broadcast after drying.
(2) For more than 3 years of rotation, the disease-free soil or seedbed soil disinfection should be selected for the seedbed to reduce the initial infection source. Covering with plastic film can reduce the chance of spreading bacteria and reduce the damage; increase the application of phosphorus and potassium fertilizer to improve the disease resistance of plants.
(3) Strengthen the humidity management of the room temperature. After 7 days of low temperature treatment, cucumber seedlings can develop resistance to anthracnose, and the induced resistance lasts for 8 days. Ecological control in the shed, that is, ventilation and drainage, so that the humidity in the shed is kept below 70%, reducing leaf surface condensation and spitting. Field operations such as disease removal, tying vines, harvesting, etc. should be carried out after the dew is dried, reducing the spread of human transmission.
(4) The plastic shed or greenhouse is applied by the smoke method or the dust method. In the evening, use 45% bactericidal bactericide , 250g once every 667 square meters, or spray 6.5% methyl sulphide and mildew dust, 5% chlorothalonil dust or 8% gram of anthrax dust. 667 square meters 1 time 1kg. Once every 9 to 11 days, use continuously or alternately.
(5) Spraying 25% prochloraz emulsifiable concentrate 1000 times solution or 50% prochloraz and manganese salt WP 1500 times solution, 60% Fu·Fu Zinc WP 7000 times solution, 40% in the early stage of the disease Dolfu bromide wettable powder 800 times solution, 1% polymycin water 300 times solution, 68.75% oxazolone manganese zinc water dispersion granule 800 times solution, 70% propyl zinc wettable powder 600 times solution, 30% phenylthiazinium emulsifiable concentrate 1000 times solution, 50% ether oxystrobin dry suspension agent 3000 times solution, 70% daisen dry suspension agent 600 times solution, 2.5% flavonoids suspension agent 1000 times solution, Once every 7 to 10 days, continuous control 2 to 3 times.
(6) Planting cucumber with soil added with manure can significantly inhibit the occurrence of anthracnose, and the relative control effect is 76.9%.
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