Origin
Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. is a member of the Fabaceae family, which is native to tropical Asia. It is commonly known as the yardlong bean or asparagus bean and has been cultivated for over 2,000 years in China and Southeast Asia.
Common Names
Aside from yardlong bean and asparagus bean, Vigna sinensis also goes by the names of Chinese long bean, snake bean, and pea bean. In the Philippines, it's referred to as sitaw while in Thailand it's known as tua fak yao. In Japan, it's called juroku-dou
Uses
Yardlong beans are a popular ingredient in many Asian dishes and are a good source of fiber, protein, and vitamins C and K. They can be eaten raw or cooked and are often stir-fried or added to soups and stews. In addition to its culinary uses, yardlong beans are also cultivated as a forage crop for livestock and as a cover crop to improve soil quality.
General Appearance
Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. is a climbing plant that can reach up to 4 meters in height. It has long, slender pods that are typically 30-90 cm in length and 1-3 cm in diameter. The pods are either green or purple in color and can be straight or slightly curved. The plant has trifoliate leaves and produces small white or purple flowers.
Light requirements
Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. requires full sunlight exposure to grow optimally. It is not tolerant of shade and requires a minimum of 6 hours of direct sunlight daily.
Temperature requirements
This plant is a warm-season crop with optimal temperatures ranging from 23°C to 27°C, although it can tolerate a wider temperature range. Temperature below 15°C can cause stunted growth and frost damage.
Soil requirements
Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. prefers well-drained soils that are rich in organic matter. It grows best in soils with a pH between 6.0-6.5. Sandy loam, clay loam, and silt loam soils are suitable for this plant. However, it is essential to avoid waterlogged soils, as it can cause root rot. The plant also requires regular watering in dry seasons to maintain soil moisture.
Cultivation Methods
Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. is a warm-season crop that requires well-drained soil and plenty of sunlight to grow. The seeds should be sown directly into the soil after the last frost date for your region. The recommended planting depth is 1-2 inches, and the recommended spacing is 4-6 inches apart.
Watering Needs
It is essential to keep the soil moist during the growing season, especially during the flowering and fruiting stages of the plant. Water the plants regularly, providing enough moisture to the soil to prevent it from drying out. Be careful not to overwater the plants, as this can lead to root rot.
Fertilization
Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. plants benefit from fertile soil rich in organic matter. Before planting, incorporate compost or well-rotted manure into the soil. During the growing season, feed the plants every three to four weeks with a balanced fertilizer. Avoid using high-nitrogen fertilizers, as they can promote leafy growth rather than bean production.
Pruning
Pruning is not necessary for Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. plants, but it can be done to promote bushier growth and increase bean production. Pinch off the tip of the main stem when the plant reaches a height of 12-18 inches. This will encourage lateral branching and increase the number of beans produced. Additionally, remove any dead or yellowing leaves to prevent the spread of diseases.
Propagation
Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. can be propagated through both seeds and stem cuttings. The propagation method chosen depends on the availability of plant materials and the cultivation purpose.
Propagation from Seeds
The seeds of Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. can be directly sown in the field or started indoors, depending on the climate and growing season. The seeds should be soaked in water overnight to facilitate germination. Then, they can be sown at a depth of about 1 inch in the soil. In general, the seeds germinate within 5-10 days and start to produce shoots and roots. The seedlings should be thinned and transplanted when they are 5-6 inches tall to provide enough space for growth.
Propagation from Stem Cuttings
The stem cuttings of Vigna sinensis (L.) Savi ex Hassk. ssp. sesquipedalis (L.) Eselt. can also be used for propagation. The cuttings should be taken from healthy and disease-free plants in the early morning, when the plant tissues are turgid. The cuttings should be about 4-6 inches long and have a few leaves attached. The lower half of the cutting should be treated with rooting hormone and then planted in a pot or directly in the field. The soil should be moist and well-drained. The cuttings should be protected from direct sunlight and wind until they start to develop new roots and shoots, which usually takes about 2-3 weeks.
Disease Management
Vigna sinensis is vulnerable to a number of diseases. Common diseases that affect this plant are:
- Anthracnose: This is a fungal disease that causes leaf spots, stem blight, and pod rot. It can be managed by keeping the field free from weeds and debris. Foliar fungicides containing copper or mancozeb can also be used to control the disease.
- Bacterial blight: This disease causes water-soaked lesions on leaves and pods, leading to their eventual rot. It can be managed by removing infected debris and crop residue, as well as the use of copper-based fungicides.
- Mosaic virus: This viral disease causes mottling and yellowing of leaves, stunting, and reduced yield. It can be prevented by the use of virus-free seeds and the removal of infected plants from the field.
To prevent the occurrence of diseases in Vigna sinensis, it is important to practice crop rotation, maintain good field hygiene, grow resistant varieties, and apply fungicides as needed.
Pest Management
Several pests can cause significant damage to Vigna sinensis. Some of the common pests that affect this plant are:
- Aphids: These small insects suck the sap from the plant's leaves and stems, causing them to curl and distort. They can be controlled by spraying with insecticidal soap or neem oil.
- Leafhoppers: These pests cause yellowing and stunted growth of the plant by sucking the sap. They can be controlled by using insecticides such as pyrethroids or neonicotinoids.
- Cutworms: These caterpillars feed on the stem of the plant and can cause significant damage to young seedlings. They can be prevented by using physical barriers or by applying insecticides containing Bacillus thuringiensis (Bt).
Other pests that can affect Vigna sinensis include root-knot nematodes, whiteflies, and spider mites. To prevent pest infestations, it is important to maintain field hygiene, monitor the plants regularly, and apply insecticides as needed.
