Description of Ambrosia hispida Pursh
Ambrosia hispida Pursh, also known as hispid ragweed, balsamweed, or bitterweed, is a species of herbaceous plant in the family Asteraceae. It is native to North America and can be found in the western and central regions of the United States, as well as in parts of Canada and Mexico.
General Appearance
Ambrosia hispida Pursh typically grows up to 40 inches tall, with a sparsely branched stem that is covered in short hairs. The leaves are smooth and either green or gray-green in color, with finely serrated edges. The flowers are small and greenish-yellow in color, arranged in clusters at the top of the stem. The plant produces a small fruit with a single seed.
Common Names and Uses
As its common names suggest, hispid ragweed is not a desirable plant in many situations. It is considered a weed in crop fields, gardens, and other areas where it competes with other plants for nutrients. Additionally, it can cause allergies in some individuals. However, the plant has some traditional uses in Native American medicine, where it has been used to treat colic, fever, and various skin conditions.
Ambrosia hispida Pursh has also been used as a natural pesticide in some cultures. When crushed and applied to the skin, it is believed to repel mosquitoes and other insects.
Light Requirements
Ambrosia hispida Pursh, commonly known as woolly bur ragweed, typically grows in full sun to partial shade. It requires at least six hours of direct sunlight per day to thrive. Too much shade may result in leggy or weak growth and reduced flowering.
Temperature Requirements
While woolly bur ragweed is tolerant of a wide range of temperatures, it typically grows best in warm temperatures between 70 and 85 degrees Fahrenheit (21 to 29 degrees Celsius). In zones where winters are harsh, it should be protected from frost and excessive cold. This plant is suitable for USDA hardiness zones 6 to 9.
Soil Requirements
Woolly bur ragweed prefers well-draining, slightly acidic soils with a pH between 5.5 and 6.5. It is adaptable to a variety of soil types, including sandy and loamy soils. However, it does not tolerate waterlogged soils, so it is important to ensure adequate drainage. This plant is drought-tolerant but may require supplemental watering in periods of prolonged drought.
Cultivation Methods
Ambrosia hispida Pursh is a hardy perennial that can be grown in different types of soils, ranging from loamy to sandy. It can also tolerate partial shade or full sunlight, but it grows best in well-draining soil under full sun. Cultivate the soil to a depth of 12-15 inches and mix organic matter and compost. Sow the seedlings in spring a week after the last frost for optimal growth.
Watering Needs
Ambrosia hispida Pursh needs regular watering to maintain healthy growth. Water the plant thoroughly once a week or every two weeks if it has rained in between. It is essential to avoid standing water around the roots as it can cause root rot. During hot and dry weather, water the plant more frequently but reduce the amount of water in the colder months.
Fertilization
Fertilize the Ambrosia hispida Pursh plant with a balanced fertilizer, such as 10-10-10, during the growing season from spring to fall. Apply the fertilizer in the soil around the base of the plant, following the manufacturer's instructions on the package. Avoid fertilizing in the winter months as the plant is dormant and does not need nutrients at that time.
Pruning
Pruning is not essential for Ambrosia hispida Pursh, but it can help maintain a neat appearance. Cut back the stems to about half their length in late fall or early spring. This will encourage bushier growth and more flowers. Deadheading the spent blooms throughout the growing season can also promote the growth of new flowers. Always use sharp, clean pruning shears to avoid damaging the plant.
Propagation of Ambrosia hispida Pursh
Ambrosia hispida Pursh, commonly known as hairy bursage or sand bursage, is a herbaceous perennial plant native to North America. It is a member of the Asteraceae family and can be propagated using various methods:
Seed Propagation
The most common method of propagating Ambrosia hispida Pursh is through seed propagation. Seeds of Ambrosia hispida Pursh are easy to collect when the seedhead mature and dry on the plant. The seeds can be collected and stored in a dry place until planting time.
When planting seeds, it is recommended to stratify them for a few weeks in the refrigerator before planting. This process helps break seed dormancy and promotes germination. Seeds can be sown directly into the soil during the fall season, preferably in October, and will germinate in the spring.
Vegetative Propagation
Ambrosia hispida Pursh can also be propagated vegetatively. The best time to propagate bursage vegetatively is during early spring or late fall by cuttings. To take cuttings, cut 4 to 6 inches length of the stem and remove the bottom leaves. The cutting should be inserted in humid soil in a greenhouse or indoors. It should be kept moist to allow new root growth.
Another way to propagate Ambrosia hispida Pursh vegetatively is through division. To do this, dig up the plant and divide the root mass into sections. Each division should have a good portion of roots and tops. Replant each division in a well-draining soil mix, and water well.
Disease Management
There are a few diseases that can affect Ambrosia hispida Pursh, such as:
- Powdery Mildew: a fungal disease that causes a white, powdery substance to form on the leaves. It can be controlled by removing and destroying infected plant parts and maintaining good air circulation around the plant.
- Root Rot: a fungal disease that attacks the roots, causing them to rot and eventually kill the plant. It can be prevented by ensuring proper drainage and watering practices.
- Leaf Spot: a fungal disease that causes circular brown spots on the leaves. It can be controlled by removing and destroying infected plant parts and maintaining good air circulation around the plant.
Pest Management
Ambrosia hispida Pursh can also be attacked by pests, such as:
- Aphids: tiny insects that suck on the sap of the plant, causing stunted growth and yellowing leaves. They can be controlled by spraying the plant with water or insecticidal soap.
- Spider Mites: extremely small pests that suck on the sap of the plant, causing yellowing leaves and webbing on the plant. They can be controlled by spraying the plant with water or insecticidal soap.
- Caterpillars: larvae of moths and butterflies that can eat the leaves, causing defoliation. They can be controlled by manually removing them or using natural predators such as birds or parasitic wasps.
It is important to inspect Ambrosia hispida Pursh regularly for signs of disease or pests and to take action promptly to prevent further damage. Maintaining good cultural practices, such as proper watering and fertilization, can also help to keep the plant healthy and resistant to disease and pests.
