Cucumber bacterial horn spot can occur in both protected and open fields, which can cause yield reduction or even no harvest, and is a major disease of cucumber.
【Symptoms】Mainly harmful leaves, but also can infect stems, petioles, tendrils, fruits, seeds, etc. When the true leaves are infected, water-soaked greenish spots appear first, and the lesions are polygonal due to the restriction of leaf veins (Fig. 1), milky white pus can be seen on the dorsal lesions when the humidity is high (Fig. 2), and when the pus is dry, it is a white film or white powder, and the diseased parts are brittle and easy to perforate (Fig. 3). The stem and petiole are infected, and the water-soaked dots are formed first, and then strip-shaped lesions are formed along the direction of the stem groove, and the lesions are depressed and cracked in severe cases. The tendrils are infected, and in severe cases, the diseased part rots and the tendrils break. Fruit infection can form irregular or continuous lesions on the surface of the fruit, and the flesh near the vascular bundle inside the fruit becomes brown, and when the humidity is high in the later stage, the diseased part produces a large amount of pus, which is in the shape of water beads, and the fruit is soft rot and has a peculiar smell.
The lesions are polygonal
When the humidity is high, there will be milky white pus
Late lesion perforation
【Pathogenesis】The pathogen overwinters in the soil, on diseased residues or seeds, and becomes the source of infection at the beginning of the next year. Germs are spread through rainwater, irrigation water, or farming practices. Seed carriers can spread over long distances. The suitable temperature for the onset of the disease is 24~28 °C, the highest is 39 °C, the lowest is 4 °C, the relative humidity of the air is more than 80%, and the leaf surface is very easy to develop when there is a water film.
【Prevention and control methods】
1. Agricultural control:
Crop rotation with non-melon crops for more than 2 years. Choose disease-free seeds or sterilize them by blanching and soaking seeds; Adopt disease-free soil seedlings to cultivate disease-free strong seedlings; Timely removal of sick and disabled bodies to reduce pathogenic bacteria; Strengthen management, try to avoid high humidity environment, and use plastic film covering, timely ventilation and other methods to reduce humidity.
2. Pharmaceutical prevention and control:
72% agricultural streptomycin sulfate soluble powder 3000~4000 times; 88% hydratemycin soluble powder 1500~2000 times; 3% Zhongshengmycin wettable powder 600~800 times liquid; 600~800 times of 20% leaf dry azole wettable powder; 20% thiazole zinc suspension 300~500 times + 12% copper pine ester emulsifiable concentrate 600~800 times; 20% thioxene copper suspension 1000~1500 times; 20% azolone aqueous solution 1000~1500 times; 40% amber · aluminum · nail cream wettable powder 1000~1500 times liquid; 50% chlorobromoisocyanuric acid soluble powder 1500~2000 times; 36% trichloroisocyanuric acid wettable powder 1000~1500 times; 86.2% cuprous oxide wettable powder 2000~2500 times; 77% copper hydroxide wettable powder 800~1000 times liquid; For water spray, spray once every 5~7 days depending on the condition.
Source: Liaoning Agricultural Sciences