Overview
Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray, also known as Prairie Dock or Prairie Rosinweed, is a flowering plant species belonging to the family Asteraceae. It is native to North America and can be found throughout the eastern half of the United States.
Appearance
Prairie Dock is a tall, sturdy plant that typically grows up to 6 feet in height. It has a thick stem with large, lance-shaped leaves that are deeply lobed. The leaves can be up to 1 foot long and 6 inches wide. The plant produces bright, yellow flowers that bloom in mid to late summer. The flowers are daisy-like and can be up to 4 inches in diameter. They are held high above the leaves on long stems.
Uses
The roots of Prairie Dock have been used by Native Americans for medicinal purposes, including treating skin conditions, coughs, and other respiratory ailments. The plant has also been used as a natural insect repellent. Prairie Dock is a popular ornamental plant in gardens and landscaping due to its tall and showy presence. Additionally, it is an important plant for supporting pollinators such as bees and butterflies.
Cultivation
Prairie Dock plants are easy to grow and maintain. They prefer full sun but can tolerate some shade. The plant is tolerant of a wide range of soil conditions, including poor soil and drought. Prairie Dock spreads by rhizomes, so it can be divided and transplanted to other areas of the garden. It is also possible to collect the seeds from the flowers and grow new plants from seed.
Light Requirements
Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray requires full sunlight to thrive. The plant prefers a minimum of 6 hours of direct sunlight each day. In conditions with partial shade, the plant may grow taller, but it will produce fewer flowers and may become spindly.
Temperature Requirements
The plant prefers warm temperatures between 20 and 30°C (68–86°F). Temperatures below 10°C (50°F) may cause the plant to go dormant, while temperatures above 35°C (95°F) can cause stress and leaf wilt.
Soil Requirements
Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray grows well in well-drained, fertile soil. The soil pH should be between 6.5 and 7.5. In areas with heavy clay soil, amending it with organic matter like compost can improve drainage and provide nutrients. The plant can also tolerate sandy soil, but requires regular watering to prevent drought stress.
Cultivation Methods
Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray, also known as Prairie Dock, is a perennial plant native to the central and eastern regions of the United States. It is a tough plant that grows well in a wide range of soils, including clay, loam, and sand. The plant prefers full sun to partial shade and grows up to 7 feet tall. To grow Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray, you can start by planting seeds directly into the ground. It is best to plant the seedlings in the late spring or early summer when the soil is warm. The plant grows a deep taproot, so the soil needs to be loose to allow for proper root development. Once established, this plant requires minimal maintenance, making it a great addition to any landscape.Watering Needs
Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray is a drought-tolerant plant that does not require frequent watering. It can survive long periods without water, making it ideal for gardens in drier areas. However, it is essential to water the plant regularly during the first year of planting to help establish the root system. Afterward, it is best to water the plant only when the soil is dry.Fertilization
Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray does not require excessive fertilization. It grows well in nutrient-poor soils, and over-fertilization can cause the plant to become leggy and flop over. However, it is helpful to add a slow-release fertilizer to the soil during the first year to help with root development. Use a balanced fertilizer once a year in the spring if the plant shows signs of nutrient deficiency.Pruning
Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray is a low-maintenance plant that does not require extensive pruning. However, it is best to cut back the plant in early spring before new growth begins to maintain its shape and prevent it from becoming too tall or leggy. You can also deadhead the plant after the flowers bloom to encourage more blooms in the future. Remove any diseased or damaged plant material throughout the growing season to ensure plant health.Propagation of Silphium Terebinthinaceum Jacq. var. Pinnatifidum (Ell.) Gray
Silphium terebinthinaceum Jacq. var. Pinnatifidum (Ell.) Gray, commonly known as Prairie Dock, is propagated through various methods including seed propagation, transplanting, and root division. Propagation of Prairie Dock is typically done in the spring or autumn seasons.
Seed Propagation
The most common method of propagating Prairie Dock is through seed propagation. Seeds from mature plants can be collected and sowed directly into the soil. It is recommended to stratify the seeds, by placing them in the refrigerator for three to four weeks before sowing, to break down their natural dormancy. Seeds can also be started indoors and transplanted to the garden once they have germinated and reached a suitable size.
Transplanting
Prairie dock can also be propagated through transplanting. This involves taking a piece of the root and replanting it in a new location. When transplanting the plant, it is essential to ensure the root system remains intact and that the roots are given enough space to grow in the new location. Transplanting is generally done in the fall when the plant is not actively growing, making it less likely to be damaged during the process.
Root Division
Root division is also a common method of propagating Prairie Dock. It involves dividing the plant's root system into sections and replanting them in new locations. This method is typically used when the plant is already established in a garden but needs to be divided due to overcrowding or to propagate more plants. Root division is best done when the plant is in a dormant state during the fall season.
Common Diseases and Pests of Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray
Several pests and diseases can adversely affect the growth and yield of Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray. Being aware of the common diseases and pests and taking preventive measures can help maintain the health of the plants and ensure a good harvest.
Diseases
Bacterial Blight: This disease is caused by the bacterium Pseudomonas syringae and can cause severe damage to leaves, stems, and flower heads of Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray. The infected parts become black and rot. The disease spreads through rain splashes, irrigation, pruning, or insects and can be prevented by practicing good sanitation measures and avoiding overhead irrigation. Infected crops should be removed and destroyed, and copper-based fungicides can be used to manage the disease.
Fungal Leaf Spots: This disease is caused by various fungi and affects the leaves of the plant, causing small lesions or spots with a brown or black color. The disease spreads through water splashes or wind and can be managed by ensuring good air circulation through proper plant spacing, avoiding overhead irrigation, and fungicide applications.
Pests
Tarnished Plant Bug: These insects damage the plants by sucking sap from the leaves and flowers. They also transmit viral diseases. The insects can be removed by spraying insecticidal soaps or neem oil on the plants.
Cutworms: These caterpillars of various moths can cut through the stem base and damage or kill young seedlings. Physical barriers such as collars made of paper or cardboard can be placed around the seedlings to prevent cutworms’ access to the stem. Pesticides are also an effective way of controlling cutworms.
Spider Mites: These tiny pests suck sap from the plants, causing yellowing and stunted growth. The symptoms of spider mite damage are often confused with nutrient deficiencies. Infected plants can be sprayed with insecticidal soap or a jet of water to dislodge the mites. Predatory mites can also be released to control spider mites.
Regular scouting of the plants to identify and manage any pest or disease problems promptly is crucial for the successful cultivation of Silphium terebinthinaceum Jacq. var. pinnatifidum (Ell.) Gray.
