How to control the white rust of amaranth by shedding leaves and swollen stems

Incidence regularity and symptoms of white rust of amaranth

White rust of amaranth

The main results are as follows: 1. the pathogen of white rust mainly overwintered with the diseased remains of amaranth in the soil, and produced conidiospores or direct infection in the following year. Perennial continuous cropping, low terrain, poor drainage, easy to accumulate water after rain, high planting density, often flooded irrigation, serious disease.

2. Amaranth is prone to white rust during the growing period, such as continuous rain, sunny day after rain, high temperature and humidity, dense plant growth, partial application of nitrogen fertilizer and so on.

3. Amaranth white rust harms the leaves. At the initial stage of the disease, yellow stains appear on the front of the leaves, yellowish green to yellow spots, then develop into sunken maculae, irregular shape, white blister spores are produced on the back of the leaves, round to amorphous. The blister spore pile ruptured and scattered white sporangia. In severe cases, blister spots are densely covered on the leaves or connected, and the leaves are uneven, which can easily cause the leaves to fall off. When the stem was killed, it was swollen and deformed, which was 1-1.5 times thicker than the normal stem.

Control methods of white rust of amaranth

1. It is best to carry out rotation with crops such as Gramineae, select disease-resistant varieties, and do not carry out rotation. Before sowing, 4000 grams of seedbed code is used per mu (resistance to repeated cropping, seed dressing, repelling underground diseases and pests and isolating virus infection), which does not affect the function of germination and swelling, can strengthen soil respiration, improve seed germination rate, and at the same time, it is best to use strip sowing or ridge cropping to strictly control seed consumption and sowing density. It helps to prevent the occurrence of white rust.

2. Select the fields with flat terrain and not easy to accumulate water, strengthen the management of fertilizer and water, promote the robust growth of plants, drain the stagnant water in the field in time after rain, and plant sparsely.

3. The growing period of amaranth should include time seedlings and thinning of over-dense seedlings, so as to facilitate ventilation, drainage and humidity reduction, reasonable irrigation, small water frequently irrigated, not flood irrigation, formula fertilization, pay attention to the application of boron fertilizer, phosphate fertilizer and potassium fertilizer, avoid partial application of nitrogen fertilizer, formula fertilization can enhance the stress resistance of amaranth, and timely spray 150ml potassium dihydrogen phosphate to make the stem of amaranth stout, leaves fat, and improve the natural taste of amaranth.

4. Chemical control: from the onset of amaranth white rust to the early stage of the disease, 150 ml of 58% Remicol-Manganese-zinc wettable powder, 60 ml of Baitai (pyrazolyl ester) or 64% poisonous alum 150 ml mixed with 50 kg of water were sprayed evenly, once every 5 days and 3 times in a row, and the use of drugs was prohibited 7 days before harvest.