Leaf, fruit, stem, scab spot, pepper scab disease prevention and treatment in greenhouse

pepper scab

I. Symptoms of harm:

It occurs in pepper seedlings, leaves, stems, fruits and other parts, and leaves occur generally. Seedling disease, water-like silvery white spots on cotyledons, gradually turning pale black concave disease spots; adult stage, diseased leaves primary water-like yellow-green spots, later expanded into irregular shape, dark brown edge, slightly raised, light color in the middle, slightly concave, rough surface, like scab. Several spots together were irregular large spots. Heavy damaged leaves, leaf margins, leaf tips become dry, cracked, and finally shed. If the disease occurs along the vein, it often causes leaf deformity.

Stem or fruit stalk disease, initially water-stained irregular stripes, then dark brown, raised, longitudinal crack, scab shape.

The fruit is damaged, initially black or dark brown raised dots, or herpes. The margin of the lesion is water-stained and slightly raised. The disease spot is round or long round black brown scab shape. There is a crack at the edge of the spot, and when it is wet, the middle spills pus.

II. Pathogen and route of transmission:

Pepper scab is caused by Xanthomonas spp. Pathogens can overwinter on the surface of seeds and become long-distance infectious sources, or overwinter in soil with diseased bodies. Field dispersal mainly depends on irrigation and farming practices. The bacteria can only invade from plant wounds and orifices. After the disease occurs, the infected part overflows with pus, which can be transmitted repeatedly.

III. Conditions of disease:

High temperature and humidity were the main conditions for inducing pepper scab, so the disease occurred seriously in greenhouse, with the lowest temperature of 5℃ and the optimum temperature of 27~30℃. Under high temperature and humidity, the disease spots expanded rapidly, pepper grew poorly, the field closed, and the disease was serious.

IV. Prevention and control measures:

1. Seed treatment. Pepper seeds can be soaked in warm soup at 55℃ for 10 minutes or soaked in agricultural streptomycin and neophytin for 30 minutes, or soaked in 1% copper sulfate for 5 minutes, washed and germinated. In addition, it can also be soaked in 1‰ potassium permanganate for 15 minutes, but it must be washed and then germinated.

2. Rotation. Rotation with other hosts except pepper, sweet pepper and tomato is carried out for 2~3 years.

3. Strengthen management. After pepper planting, it is necessary to loosen soil and topdressing in time to promote root development. In greenhouse cultivation, special attention should be paid to ventilation, cooling and moisture removal.

4. Chemical control. Available agents: 1:1:200 times Bordeaux mixture, streptomycin or neophytin 4000 times, 60% aluminum succinate (DTM) wettable powder 500 times solution, 77% copper-hydroxide (copper hydroxide) wettable powder 400~500 times spray. Choose one of the above agents, alternate medication, spray once every 7~10 days, and spray 2~3 times according to the condition.

5. Sick plants, sick leaves and sick peppers should be collected in time and taken outside the field for centralized destruction.