Symptoms, Identification and Control of Kidney Bean Wilt Disease
The kidney bean is a warm-loving plant. The suitable temperature for growth is 15-25°C, and the suitable temperature for flowering and pod setting is 20-25°C. Low temperatures below 10°C or high temperatures above 30°C will affect growth and normal pollination and pod setting. It is a short-day plant, but most varieties are not strict about day length, and the cultivation season is mainly restricted by temperature. In the northwest and northeast regions of China, it is cultivated in spring and summer; in north China, the Yangtze River basin and south China, it is sown in spring and autumn.
The kidney bean is rich in nutrients, and the fresh beans also contain abundant vitamin C. In terms of nutritional composition, the protein content is higher than that of chicken, the calcium content is more than 7 times that of chicken, iron is 4 times, and the B vitamins are also higher than those of chicken.
The edible value of the kidney bean
Tender pods contain about 6% protein, 10% fiber, and 1-3% sugar. Dry bean seeds contain about 22.5% protein and 59.6% starch. The fresh tender pods can be eaten as a vegetable, and can also be dehydrated or canned. The kidney bean is also a rare high-potassium, high-magnesium, low-sodium food, and this characteristic is of great use in nutritional therapy. The kidney bean is especially suitable for patients with heart disease, arteriosclerosis, high blood lipids, hypokalemia, and those who must avoid salt.
The medicinal value of the kidney bean
According to modern medical analysis, the kidney bean also contains unique components such as saponins, urease, and various globulins, and has functions such as improving the body's blood and immune capacity, enhancing disease resistance, activating lymphatic T cells, and promoting the synthesis of deoxyribonucleic acid. It has an inhibitory effect on the development of tumor cells, and has therefore attracted the attention of the medical community. The urease it contains has a very good effect when applied to patients with hepatic coma.
Understanding and control of kidney bean wilt disease
What is wilt disease?
It is a general term for plant diseases such as Fusarium wilt, Verticillium wilt, and bacterial wilt, mainly caused respectively by fungi of the genus Fusarium, fungi of the genus Verticillium, and bacteria of the genus Pseudomonas. The Fusarium fungi that cause Fusarium wilt have relatively high parasitic specialization; for example, Fusarium oxysporum has more than 70 specialized forms that respectively infect certain hosts. Although fungi of the genus Verticillium have a very wide host range within the same species, their pathogenicity differs markedly. The pathogenicity of Ralstonia solanacearum also differs markedly among different hosts.
The kidney bean wilt pathogen is a short small bacillus, Gram-positive, motile, non-spore-forming, 0.3-0.5×0.6-3.0μm, with 1-3 lateral or polar flagella, straight to slightly curved or wedge-shaped, arranged singly or in V, Y shapes or palisade-like rows.
Harmful symptoms of the kidney bean wilt pathogen: The kidney bean wilt pathogen infects seedlings through diseased seeds or overwintering residues, usually causing death. If the seedling survives, no leaves grow. The most typical symptom of the kidney bean is that the seedling leaves gradually wilt, accompanied by discoloration, and the plant becomes dwarfed. Young branches die. Discolored leaves usually have dark green, brown, or reddish-brown lesions; the discolored area first softens and then dries up, and water-soaked inoculation of leaves produces white blisters. Sometimes the above symptoms are lacking, and the leaves show golden-yellow necrotic spots or only partial wilting of the leaves, similar to common bacterial blight of kidney bean (Xanthomonas campestris pv. phaseoli), but after the latter infects kidney bean pods, there are discolored lesions along the pod sutures, usually yellow-green, somewhat wilted, and sometimes the surface is sunken. On mature pods, the lesion areas are green-brown and the rest is yellow. Infected seeds have yellow lesions of different sizes and shapes and are very easy to distinguish from healthy seeds.
When the pod is opened, yellow bacterial ooze can be seen, and there are water-soaked spots on the stems and leaves. Kidney bean stems generally have rust-colored lesions; the pathogen survives in the vascular bundles and causes them to turn brown, and stem inoculation produces interveinal yellowing and necrosis of the leaves. Orange-yellow and purple variant strains infect seeds, and there are orange-yellow and purple faded spots on the seed coat. Both seedlings and adult plants of soybean are susceptible. Small chlorotic spots first appear on the leaves, then enlarge, and chlorosis begins along the leaf margins toward the midrib. Infected tissue dries, turns brown, and dies; under windy conditions, the browned parts fall off, and the leaves appear rough. When seeds carrying the pathogen are planted, the seedlings are dwarfed, with marginal leaf necrosis or necrotic spots on the leaves, and pods form abnormally, but no symptoms have been observed on the pods and stems.
Control methods for the kidney bean wilt pathogen:
The main control approaches are implementing strict quarantine to protect disease-free areas, selecting disease-resistant varieties in diseased areas, practicing crop rotation, disinfecting seeds carrying the pathogen, and switching crops or disinfecting the soil in heavily diseased fields.
1) Seed disinfection: before sowing, soak the seeds in warm water at 56°C for 5 minutes.
2) Practice crop rotation for more than 3 years, and for paddy fields practice crop rotation for more than 2 years.
3) Choose fields with soil water content higher than 70% for planting.