Timely prevention and control of rust of growing leek

Leek rust mainly infects leaves and pedicels, initially produces yellow dots on the epidermis, and gradually develops into orange blister spots with spindle or oval eminence, and there is often a yellow halo around the spot. Blister expansion is larger, to its epidermis rupture, scattered orange powder, that is, summer spores. Both sides of the leaves can get sick and start to spot. Farmers in Guangdong often call it "ink shit". After the summer spores are scattered, they call it "rust color". The biggest feature of the disease is that it develops rapidly and comes fiercely. When the disease is serious, blisters are covered with leaves, lose edible value, and cannot be put on the market for sale. resulting in greater economic losses.

The pathogen of leek rust is onion stalk rust, which is a highly parasitic higher fungus, which can infect many kinds of Liliaceae besides leek. Winter spores are generally not produced in South China, and their parasitism and overwintering are not found. they are transferred and infected by summer spores every year, and with the help of airflow transmission, the wet water film on the plant epidermis is the most likely to germinate and directly invade through the epidermis. In general, in autumn, winter and spring in Guangdong, the weather is warm and humid, especially in drizzle or dewy foggy weather. If the variety has poor disease resistance, too much nitrogen fertilizer is applied. The disease is more serious when the planting is too dense and the potash fertilizer is insufficient.

Measures should be taken to prevent and cure the disease from the following aspects:

1. Reasonable close planting, cut as low as possible during harvest, and clean the border surface as far as possible to reduce pathogens in the field. Then spray 45% colloidal sulfur 400 times to disinfect the border surface.

2. Watering is not easy to get too wet, pay attention to field drainage after rain, adopt reasonable formula fertilization, and pay attention to increase the application of phosphorus and potassium fertilizer. Leek seedlings should be foliar sprayed with potassium dihydrogen phosphate or potassium sulfate to improve plant disease resistance.

3. Timely spraying prevention and treatment in the early stage of the disease, without delay, available medicaments are as follows: bacterial flax (40% wettable powder) 500ml 600x, spot powder or nitrilozole (12.5% EC) 1200ml 1500 times, triadimefon (20% EC) 1500Lue 2000 times, Dilitu (25% EC) 3000 times. The disease can be effectively controlled by spraying 1 Mel once every 10 days.