Origin
Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh is a plant species that belongs to the Fabaceae family. It is native to North America, where it can be found in several regions such as the Mackenzie River Valley, Western Canada, and the Rocky Mountains.
Common Names
The plant is commonly known as Robust milkvetch, Laxmann's milkvetch, and Laxmann's milkvetch var. robustior.
Uses
The plant has several medicinal properties, and it has been used by indigenous communities as a herbal remedy for various ailments such as coughs, colds, and respiratory diseases. The plant contains saponins, which have been found to have anti-inflammatory and antitumor effects. Astragalus laxmannii Jacq. var. robustior has also been used as a forage crop for livestock and as a soil stabilizer due to its nitrogen fixation abilities.
General Appearance
The plant is a perennial herb that can grow up to 50 cm tall. It has a deep taproot that allows it to survive in harsh environments. It has alternate leaves that are pinnately compound, and each leaf has 11 to 29 leaflets that are elliptic to lanceolate in shape. The flowers of the plant are pink, purplish-blue or white and are arranged in a raceme inflorescence. The fruit of the plant is a legume that contains several seeds, and it is covered with hair.
Light Requirements
Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh requires full sun to grow properly. This plant does not tolerate shady conditions as it needs adequate sunlight to photosynthesize and produce sufficient energy for growth and reproduction.
Temperature Requirements
The plant can grow and develop well in climates with hot and dry summers and cold winters. Its growth rate increases during the warm months. The species can grow in areas where the temperature can range from -40°C to 30°C.
Soil Requirements
The plant prefers well-drained and nutrient-rich soil and can tolerate a wide range of soils in terms of pH. However, it is advisable to cultivate it in soil with a pH ranging from neutral to slightly alkaline (6.8-8.5). Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh can tolerate drought conditions too but does not grow well in waterlogged soil. As it belongs to the legume family, the plant can fixate atmospheric nitrogen into usable forms for growth, provided the soil has the necessary rhizobia bacteria.
Cultivation Methods
Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh, commonly known as the "Robust Laxmann's Milk Vetch," is a perennial plant that requires well-draining soil with a slightly alkaline pH level. It is best to cultivate this plant during the spring or fall, where the temperature is mild, and there is moderate sunlight. Planting the seeds in a sunny or partially shaded area with good airflow is also essential when growing this plant.
Watering Needs
Adequate watering is necessary during the growing season of Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh. This plant requires moderate to low water, depending on the climate and rainfall in the area. In well-draining soil, water deeply every week, and avoid watering the leaves to prevent fungal diseases from developing. During the winter, reduce waterings to prevent rotting or waterlogging of the soil.
Fertilization
The use of fertilizers is crucial when growing a healthy Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh plant. Fertilize this plant using a balanced slow-release fertilizer in early spring and thereafter on a monthly basis when the plant is actively growing. Avoid fertilizing in winter as the plant is not actively growing at that time.
Pruning
Pruning is not necessary for the Robust Laxmann's Milk Vetch, but removal of dead or damaged stems, leaves and flowers can improve the plant's appearance and overall health. Cutting back the plant to ground level after the growing season can also promote new growth and a healthier plant the next year. Performing any significant pruning or trimming during the winter dormant period is not recommended.
Propagation of Astragalus laxmannii Jacq. var. robustior
Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh can be propagated using different methods, including seed propagation and vegetative propagation.
Seed Propagation
Seed propagation involves sowing seeds in the appropriate conditions to allow for germination and growth. Seeds of Astragalus laxmannii Jacq. var. robustior can be sown directly in the ground in the fall, allowing for natural stratification over the winter. Alternatively, they can be stratified indoors for six weeks at 40 degrees Fahrenheit before planting in the spring.
The seeds should be sown in well-drained soil and covered with a thin layer of soil. They should be watered regularly, and the soil should be kept moist until germination, which usually occurs within two to four weeks.
Vegetative Propagation
Vegetative propagation involves using parts of the existing plant, such as roots, stems, or leaves, to create new plants. Astragalus laxmannii Jacq. var. robustior can be propagated vegetatively through cuttings.
Softwood cuttings should be taken in the spring when the new growth is soft and pliable. The cuttings should be about 6 inches long and should have several leaves on them. They should be stripped of the lower leaves, dipped in rooting hormone, and planted in well-draining soil. The cuttings should be kept moist and covered to maintain humidity until they root.
Hardwood cuttings should be taken in the fall when the plant is dormant. The cuttings should be about 8 inches long and should be taken from one-year-old wood. They should be planted at a slant in well-draining soil and kept moist until they start growing in the spring.
Disease and Pest Management for Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh
Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh is a hardy plant and is relatively resistant to most diseases and pests. However, it can still be affected by a few common diseases and pests that can impact its health and overall growth. In this section, we will discuss the various diseases and pests that can affect this plant and how to manage them.
Common Diseases
Verticillium Wilt: Verticillium wilt is a soil-borne fungal disease that causes yellowing of leaves, wilting, and eventual death of the plant. The disease is difficult to manage once it infects the plant. However, appropriate cultural practices such as planting in well-drained soil, regular inspection of plants, and prompt removal of infected plants can help prevent the spread of the disease.
Root Rot: Root rot is another soil-borne fungal disease that affects the roots, leading to wilting, yellowing of leaves, and ultimately death of the plant. The best way to prevent root rot is to plant in well-drained soil and avoid overwatering.
Common Pests
Aphids: Aphids are small, sucking insects that can cause stunted growth and yellowing of leaves. They can also transmit viruses to the plant. The best way to manage aphids is to wash them off with a strong jet of water or use insecticidal soap or neem oil.
Spider Mites: Spider mites are small insects that cause discoloration of leaves and can lead to defoliation. They are usually found on the undersides of leaves and produce webbing. The best way to manage spider mites is to wash them off with a strong jet of water or use insecticidal soap or neem oil.
Thrips: Thrips are small insects that feed on plant sap, causing discoloration and distortion of leaves. They can also transmit viruses to the plant. The best way to manage thrips is to use insecticidal soap or neem oil.
In conclusion, Astragalus laxmannii Jacq. var. robustior (Hook.) Barneby & Welsh is a relatively hardy plant that is resistant to most diseases and pests. However, it can still be affected by a few common diseases and pests. Proper cultural practices such as planting in well-drained soil, regular inspection, and prompt removal of infected plants can help prevent the spread of diseases. Additionally, using insecticidal soap or neem oil can help manage pests such as aphids, spider mites, and thrips.
