Rust Disease Control Must Be Taken Seriously in Autumn Cowpea Planting
Cowpea (Vigna unguiculata), also called yardlong bean, is a vegetable abundantly produced in summer. It belongs to the cultivated varieties of the cowpea species that form long pods, an annual twining herbaceous plant. Also known as cowpea, long-horn bean, belt bean, and skirt-string bean. It contains various vitamins and minerals, etc. The tender pods are thick and fleshy, crisp and tender when stir-fried, and can also be blanched for cold salads or pickled. The pods are long and tube-like, crisp in texture yet soft in body, with common types including white cowpea, green cowpea, and purple cowpea. When selecting cowpeas, those with uniformly thick pods, bright color, translucent gloss, and plump seeds are generally preferred, while those with cracks, wrinkled skin, overly thin pods without seeds, or insect marks on the surface should not be purchased. Cowpea has excellent nutritional content and is the meat among vegetables.
The Benefits of Cowpea
Common bean is sweet and bland in flavor, slightly warm in nature, and enters the spleen and stomach meridians; it resolves dampness without being harsh, strengthens the spleen without causing stagnation, and is a commonly used remedy for spleen deficiency with dampness retention; it has the effects of harmonizing the viscera, calming the spirit, tonifying qi and strengthening the spleen, relieving summer heat and resolving dampness, and promoting urination and reducing swelling; it mainly treats spleen deficiency with dampness, poor appetite and loose stools, damp turbidity pouring downward, excessive vaginal discharge in women, and can also be used for summer dampness damaging the middle burner, vomiting, diarrhea, and muscle cramps.
The Nutrition of Cowpea
Traditional Chinese medicine holds that cowpea-type vegetables are sweet in flavor and neutral in nature, with effects of resolving dampness and tonifying the spleen, regulating the digestive system, tonifying the kidney and stopping diarrhea, and tonifying qi and promoting fluid production, making them especially suitable for people with weak spleen and stomach. Modern nutritional data shows that their protein content is relatively higher than that of general vegetables, and the content of various vitamins and minerals is also relatively rich, so cowpea is also praised as "the meat among vegetables."
When the body produces excessive free radicals or clears them too slowly, it accelerates aging and induces many diseases. Research shows that cowpea has a strong scavenging effect on hydroxyl free radicals, which may be related to its relatively rich content of carotene, vitamin E, ascorbic acid, and the trace element selenium. Comparative research results show that long cowpeas (such as yardlong bean) have a stronger scavenging capacity for hydroxyl free radicals than short cowpeas.
Rust Disease Must Be Taken Seriously in Autumn Cowpea Planting
Autumn-planted cowpeas grow in an environment with high temperatures and relatively high rainfall, and combined with the large amount of inoculum (urediospores) left behind in the field from spring-planted cowpeas. Therefore, autumn-planted cowpeas are prone to rust disease, and farmers should carry out comprehensive control as early as possible.
1. Main symptoms: Cowpeas can be infected by the pathogen throughout the entire growth period, but resistance weakens and susceptibility increases from the beginning of flowering to the podding stage. The disease mainly attacks leaves. In the early stage of the disease, scattered chlorotic yellowish-white spots appear on the underside of the leaves, and the spots gradually increase until they densely cover the entire leaf. On the corresponding back side of the lesions, yellowish-brown slightly raised scab-like spots, namely uredia, form. After the uredia rupture, large amounts of urediospores are released. On old leaves in the late growth stage, black telia sometimes form. The leaves turn yellow and fall off, the plant becomes stunted, the pods are few and small, the growth period is shortened, and finally the plant withers and dies.
2. Pathogen: It belongs to the Basidiomycotina, genus Uromyces. The source of infection is the diseased residues of spring-planted cowpeas or the uredia left in the field. The urediospores germinate to produce germ tubes and invade the host through stomata. At 18-25 degrees C, when air humidity is high or fog and dew are heavy, and when there is a water film on the host surface, the urediospores most easily germinate and invade the host. The diseased plants then spread urediospores through airflow, insects, and humans and livestock among plants in the field, causing frequent re-infection, and the produced telia become the primary infection source for leguminous crops planted in the following spring.
3. Control methods: Comprehensive control measures based mainly on strengthening the management of soil, seed, fertilizer, and water, supplemented by timely pesticide application.
1. Remove diseased residues and reduce the source of infection: After harvesting spring-planted cowpeas, collect and burn the remaining plants and dead seedlings to reduce the source of infection.
2. Seed selection and site selection:
(1) Seed selection and planting: Choose disease-resistant varieties, cultivate on raised beds, and it is advisable to plant in double rows or single rows, as this makes it easy to drain accumulated water and improve aeration, which is not conducive to the landing and invasion of urediospores.
(2) Site selection: It is best to choose fields where the previous crop was a grass-family crop, and not to choose fields where the previous crop was a leguminous crop or peanut. This can avoid direct attack by the rust fungus.
3. Reasonable fertilization: Apply sufficient base fertilizer, apply topdressing early, and increase the application of phosphorus and potassium fertilizers to enhance nodule activity, make the plants grow robustly, and make the leaves dark green and thick, thereby enhancing disease resistance.
4. Timely pesticide application for control: Apply pesticides promptly in the early stage of the disease. The pesticides can be 50% triadimefon at 600-800 times dilution, or 50% sulfur suspension concentrate at 500-600 times dilution, or 70% thiophanate-methyl at 800-1000 times dilution for spraying. Spray once every 8-10 days, for 2-3 consecutive sprays.