How to prevent and control red root in kidney beans? Solutions for roots that turn red, shrivel, and produce no new roots

Red root in kidney beans

   I. Symptom characteristics:

    Looking at the growth of kidney beans, the lower leaves begin to turn yellow and thin from bottom to top, and the growth vigor is relatively weak. When the plant is pulled out, the kidney bean roots are found to be red or shriveled, with very few roots or no new roots, and some roots have red strip-like lesions on the main root. Kidney beans grow slowly, and in severe cases, pod setting is affected, with flower and pod drop occurring.

    II. Causes of the disease:

    1. Root suffocation. Excessive watering leads to overly high soil moisture, and poor water and air permeability in the soil is unfavorable for normal root growth of kidney beans. Poor root growth then leads to underdeveloped roots, commonly known as "root suffocation." In severe cases, the entire root system peels or the fine roots decrease.

    2. Root burn. This is caused by fertilizers and pesticides. Excessive or unreasonable fertilization leads to root burn, and in a few cases it is related to organic fertilizer in the base fertilizer not being fully decomposed. In addition, when planting, if too much fungicide for preventing red root or nematicide is applied in the holes, or if it is not spread evenly, the excessive pesticide dose can also cause root burn in kidney beans.

    3. Overdense planting. Kidney beans are planted relatively densely, and some holes even contain 5-7 seeds, resulting in nutrient competition among plants. In general, kidney beans more often develop red root after wounds first appear and then become infected by pathogens.

    4. Too-low soil temperature. When the soil temperature is too low, the suitable soil temperature required for root growth cannot be ensured, resulting in poor root growth, difficulty in producing fine roots, and a tendency for roots to turn red.

    5. Root rot. Under overly high moisture conditions, legume roots are easily infected by root rot pathogens, resulting in red root.

    6. Anthracnose. Legume roots develop red root due to anthracnose infection, generally accompanied by red sunken spots on the stems above the soil surface and red linear spots on the veins on the underside of leaves.

    How to prevent and control red root in kidney beans:

    1. Root drenching. "Deep roots, lush leaves." Only when the roots are good can kidney beans grow well. Therefore, the roots must be well nourished. It is recommended to drench the roots once every half month to 1 month. Choose any one pesticide such as thiophanate-methyl, hymexazol, or bromothalonil, add a rooting agent, and drench the roots. This can effectively reduce plant death. Note that the dosage should be relatively large; at the adult plant stage, 4 liang to half a jin of water can be used. Note that kidney beans around diseased plants should be root-drenched 2-3 times continuously, which can effectively control disease development.

    2. Watering and fertilizing. Water with small amounts and frequent irrigation, apply fertilizer in small amounts and multiple times, and also reduce the application rate of chemical fertilizers. It is recommended to apply humic acid fertilizers or root-promoting fertilizers, which can maximize the guarantee of normal root growth. Be careful to reduce the application rate of chemical fertilizers to avoid root damage or root burn, and at the same time appropriately reduce poor root growth caused by too-low soil temperature.

    3. Foliar fertilizer spraying. Foliar fertilizers containing medium and trace elements such as calcium, magnesium, and iron can be sprayed on the leaves to promote normal leaf growth and, to a certain extent, improve the resistance of kidney beans to adverse environmental conditions.

    4. Remove diseased plants. Promptly remove kidney beans that have already developed the disease. At the same time, quicklime can be spread into the soil around the removed kidney beans to disinfect the soil, kill pathogens, and avoid large-scale infection and damage from kidney bean Verticillium wilt.

    5. Hole application of pesticides. Be careful to mix the pesticide with soil. Generally, mix at a ratio of pesticide to soil of 1:10. Note that the dosage should not be too large, which can reduce pesticide damage caused by excessive or uneven application.

    6. Properly sparse planting. This can reduce root competition in kidney beans caused by overly dense planting, avoid insufficient nutrient supply, and provide a suitable growth environment for the roots.