Symptoms and control of white rust of hollow cabbage

Asparagus, formerly known as Yongcai, also known as rattan, water spinach, water spinach, arenaria, urn vegetable, empty cauliflower, bamboo leaf cabbage, white trumpet-shaped flower its stem center is empty, so it is called "hollow vegetable". It is widely cultivated as vegetables in rural areas of southern China.

Botanical characteristics of asparagus

Rabdosia angustifolia is a trailing plant with shallow root distribution, whisker root system and strong regeneration ability. Stem trailing, round and hollow, soft, green or lavender, stem 1-2 cm thick. The stem has nodes, each node in addition to axillary buds, but also can grow adventitious roots, Internode length of 3.5 to 5 cm, the longest up to 7 cm. Cotyledons opposite, horseshoe-shaped. True leaves alternate, smooth, entire, extremely pointed, veins reticulate, midrib obviously raised, leaves lanceolate, long oval or heart-shaped. The width of the leaf is 8 cm 10 cm, the widest is 14 cm, the leaf length is 13 cm 17 cm, and the longest is 22 cm. The petiole is longer, about 12-15 cm, and the longest is 17 cm. Hollow is concave, the fruit is a capsule, nearly round, the seed is dark brown, and the dry grain weighs 32-37 grams. Asparagus propagates by seeds or tender stems, while in the north it propagates by seeds.

Due to the high temperature and heavy rain after summer, asparagus is prone to a kind of white rust, which seriously affects the production efficiency of asparagus, so what are the symptoms of white rust and how to prevent it?

What is white rust?

White rust is mainly harmful to leaves. At the initial stage of the disease, there are white nearly round to irregular blister spots slightly raised on the back of the leaves, that is, spore piles. Its surface is slightly glossy, some on a leaf as many as dozens of blister spots, mature blister epidermis rupture, scattered white powder, that is, pathogen sporangia.

Symptoms of white rust of hollow cabbage: the disease spot grows on the back of the leaf, the leaf front appears yellowish to yellow spot, then gradually turns brown, the disease spot expands, and the back of the leaf produces white protuberant blister spot, which is nearly round or oval to irregular, and sometimes heals into larger blister spots. In the later stage, the blister spot ruptures and spreads out white impotent sporangia. When the leaves are seriously damaged, the disease spots are dense, the diseased leaves are deformed, and the leaves fall off.

The prevention and control of white rust of hollow cabbage has the following three points:

First, rotation with other vegetable varieties for 2 to 3 years.

Second, before sowing, seed sterilization should be carried out according to the proportion of 100kg seeds with 300g metalaxyl; third, at the initial stage of the disease, 6000 to 7000 times solution of 50% nail cream copper wettable powder, or 8000 times solution of 72.2% Prik water agent, can be sprayed once every 7 to 10 days. To infect again. Rain Water and insects can also spread, but whether seeds can be spread remains to be studied. Cool and wet at night, warm during the day, heavy fog, and the condition of sticky and wet soil is conducive to the occurrence and prevalence of the disease.

III. Prevention and control methods

1) choose disease-free seeds and seed treatment: select disease-free land to keep seeds, soak the newly bought seeds in 50 ℃ warm water for 25 minutes, cool and sow.

2) strengthen the management of garden fields: select plots with high terrain, good drainage and ventilation for planting. Apply enough fertilizer and increase the application of phosphorus and potassium fertilizer. Irrigate properly so as not to make the green onion floor too wet. If you find a diseased plant, remove it and bury it in time. After harvest, the disease and residue were thoroughly removed, concentrated treatment, and deep ploughing was carried out to reduce the source of bacteria.

3) Chemical control: spray at the initial stage of the disease, once every 7-10 days, 3-4 times in a row. The commonly used agents are 1240,300 Bordeaux solution, 40% aluminum ethyl phosphate wettable powder 200300 times, 25% metalaxyl wettable powder 1000 times, 75% chlorothalonil wettable powder 500,600 times, 65% Dysen zinc wettable powder 500700 times, 64% poison alum, M8 wettable powder 500x. 66.5% Pulic water agent 700-1000 times.