Overview
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. is a member of the pea family, Fabaceae, and is a perennial herbaceous plant. It is commonly known as Large Black Vetch, Giant Vetch, or Wild Pea, and is mainly found in North America, specifically in California and the western United States.
General Appearance
The plant is known for its large size, growing up to 6 feet tall, with slender stems and long sprawling tendrils that can climb or scramble over other vegetation. It has pinnate leaves with 10-16 leaflets, each about 1 inch in length, and produces large dense clusters of purple to blue flowers along the stems. The fruit of the plant is a legume that contains several seeds.
Uses
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. has several uses in agriculture and horticulture. It is often planted as a cover crop to improve soil health, as it can fix nitrogen in the soil. The plant is also useful in erosion control and habitat restoration, as it has a highly efficient root system that can help prevent soil erosion. Additionally, it is attractive to pollinators such as bees and butterflies and provides an excellent food source for livestock and wildlife.
Light Requirements:
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. thrives in full sun to partial shade. The plant requires at least six hours of sunlight per day to grow optimally. When grown under partial shade, the plant may produce fewer flowers, and its growth may be stunted compared to those grown in full sun.
Temperature Requirements:
The plant can grow in a wide range of temperatures, making it suitable for growth in different climatic zones. The optimum temperature range for the Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. plant is between 18 °C and 22°C. The plant may stop growing at temperatures below 10°C, while the buds and flowers can be damaged by frost. On the other hand, extreme heat, such as those above 30 °C, can cause the plant to wilt or impair its growth.
Soil requirements:
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. prefers well-drained soils, rich in organic matter. The plant can grow in sandy, loamy, or clay soils, but it does best in soils with a pH range of 5.5 - 7.5. The soil should be moist but not waterlogged to prevent root rot, especially during the winter months when the plant is dormant. The addition of compost or well-rotted manure to the soil can enhance its fertility and improve the overall growth of the plant.
Cultivation Methods
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. prefers a well-draining soil rich in organic matter. It is best to sow the seeds directly outdoors in the fall or early spring, as the plant does not transplant well. The seeds should be planted at a depth of about 1 inch and spaced 6-8 inches apart. The plant prefers full sun but can tolerate some shade.
Watering Needs
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. prefers consistent moisture but can tolerate some drought. The plant should be watered deeply once or twice a week, depending on the weather and soil conditions. It is best to water the plant in the morning to allow the foliage to dry before evening.
Fertilization
It is best to fertilize Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. with a balanced fertilizer once a month during the growing season. The plant does not require heavy fertilization and can be damaged by excessive amounts of nitrogen. Organic fertilizers, such as compost or aged manure, are ideal for this plant.
Pruning
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. does not require regular pruning, but the plant may benefit from occasional deadheading to promote further blooming. Deadheading involves removing spent blooms and seed pods, which redirects the plant's energy towards producing new growth and blooms.
Propagation of Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn.
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. can be propagated via seeds or stem cuttings.
Propagation via Seeds
The seeds should be collected when they are mature, typically in late summer. They should be stored in a cool, dry area until ready to be planted in the soil. Seeds can be scarified by soaking them overnight in water, or by gently rubbing them with sandpaper or a file, to allow for better germination rates. Germination rates are typically high and the seedlings should be transplanted into the ground once they have grown to a suitable size.
Propagation via Stem Cuttings
Stem cuttings can be taken from the plant, typically in the spring months. The cuttings should be taken from the newer growth on the plant and should be approximately six inches in length. The leaves on the lower half of the cutting should be removed. The cutting should be dipped in rooting hormone and planted in a well-draining soil mixture. The plant should be kept moist and covered to allow for a suitable environment for rooting. Once the plant has rooted, it can be transplanted into the ground.
Disease Management
Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. can be affected by various fungal and viral diseases, such as root rot, powdery mildew, and bean yellow mosaic virus (BYMV).
To manage root rot, ensure that the soil has good drainage to prevent waterlogging. Use disease-free seeds and avoid over-watering the plants. Crop rotation with non-host plants can also be helpful.
Powdery mildew can be managed by improving air circulation around the plants and reducing humidity levels. Remove infected leaves promptly and avoid overhead irrigation. Fungicides may also be used to control the disease in severe cases.
BYMV can be prevented by using virus-free seeds and controlling aphid populations, which are the primary vectors of the virus. Early detection and prompt removal of infected plants can also help to prevent the spread of the disease.
Pest Management
The most common pests that affect Vicia nigricans Hook. & Arn. ssp. gigantea (Hook.) Lassetter & Gunn. are aphids, slugs, and snails.
Aphids can be controlled by introducing natural predators such as ladybugs and lacewings. Additionally, spraying the plants with a solution of water and dish detergent can help to deter aphids. Avoid using broad-spectrum insecticides as they can harm beneficial insects.
Slugs and snails can be kept under control by placing copper strips around the base of the plant or using slug pellets. Introducing natural predators such as birds and frogs can also help to manage these pests. Avoid overwatering the plants as this can create a favourable environment for slugs and snails.
