Fraxinus americana L. var. crassifolia Sarg.
Fraxinus americana L. var. crassifolia Sarg. is a species of tree in the olive family Oleaceae. It is commonly known as the autumn purple ash. The plant is native to North America and can be found across the United States and southern Canada.
Common Names
Fraxinus americana L. var. crassifolia Sarg. goes by various common names such as Autumn Purple Ash, Fall Purple Ash, Smooth Leafed Ash, and Purple American Ash.
Uses
The tree is primarily used for ornamental purposes due to its beautiful foliage, with the autumn purple ash being a popular landscaping tree. It can also be used as a source of timber and firewood. The leaves of autumn purple ash can be used to make herbal medicines, but it is not commonly used for this purpose.
General Appearance
Autumn Purple Ash grows up to a height of 60 – 70 feet with a spread of 45 – 50 feet. It is a deciduous tree, meaning it sheds its leaves annually. The leaves of the autumn purple ash are serrated in appearance with an elliptical shape and a shiny green color that changes to a deep purple or reddish-purple in autumn. The bark on the tree is gray-brown in color, and the branches have a smooth texture to them. The tree produces small, purple flowers in the springtime, which give way to winged fruits that fall in the autumn.
Light Requirements
The Fraxinus americana L. var. crassifolia Sarg. requires a full sun to partial shade environment for healthy growth. It prefers a minimum of six hours of direct sunlight daily. In areas with harsh summer sun, it can benefit from a cooler and shaded environment during the hottest parts of the day.
Temperature Requirements
The Fraxinus americana L. var. crassifolia Sarg. thrives in a moderate to warm temperature range. It can withstand temperatures as low as -30°F (-34°C) in winter and up to 95°F (35°C) in summer. It does not do well in areas with severe temperature fluctuations or cold temperatures, as it can damage the plant's health.
Soil Requirements
The Fraxinus americana L. var. crassifolia Sarg. thrives in well-drained and moist soil with a pH range of 6.0 to 7.5. It prefers rich and fertile soil that is slightly acidic. It does not do well in areas with poorly drained or compacted soil. It is essential to ensure good soil aeration and regular watering, especially during the hot summer months.
Cultivation Methods
The Fraxinus americana L. var. crassifolia Sarg. is a relatively easy plant to cultivate. It prefers full sun to partial shade and well-draining soil. The plant can tolerate a range of soil types but prefers slightly acidic to neutral soils. It is tolerant of some drought and compacted soils, but proper drainage is essential for its growth.
You can raise the plant from seeds or propagate from hardwood cuttings. If planting from seeds, it is best to pre-soak for a day or two before planting. Cuttings are best taken in winter or early spring and should be about 30 cm in length and 1 cm thick. Before planting, remove all leaves, and dip the cut end of the stem in rooting hormone. Plant the cutting in well-draining soil and keep it moist until it begins to show signs of growth.
Watering Needs
The Fraxinus americana L. var. crassifolia Sarg. requires moderate watering, and you need to keep the soil around the roots consistently moist but not waterlogged. Watering should be done slowly and deeply, allowing the water to reach the roots' depth. During the growing season, the plant needs consistent moisture, and you should water the plant once or twice a week. During the dormant season, the watering frequency can reduce.
Fertilization
The Fraxinus americana L. var. crassifolia Sarg. requires little fertilizer, but it can benefit from a bit of feeding in the spring or early summer. Use a balanced fertilizer, and mix it into the soil around the plant's base. Overfertilization can lead to excessive foliage growth, which can make the tree susceptible to pests and diseases.
Pruning
The Fraxinus americana L. var. crassifolia Sarg. requires little pruning other than a routine removal of any dead, diseased, or damaged branches. A yearly pruning session is essential to maintain the tree's structure and shape. If you notice any unsightly or crowded growth, remove it. Prune the tree in late winter or early spring before new growth emerges.
Propagation of Fraxinus americana L. var. crassifolia Sarg.
Fraxinus americana L. var. crassifolia Sarg. is commonly propagated through seeds, cuttings, and grafting.
Seed Propagation
Seeds of Fraxinus americana L. var. crassifolia Sarg. can be collected from the parent plant during autumn and winter. The seeds are then planted in well-draining soil and covered lightly with soil. Germination occurs within two to three weeks. Seedlings can be transplanted to pots or directly in the ground once they develop two to three true leaves.
Cutting Propagation
Cuttings of Fraxinus americana L. var. crassifolia Sarg. can be taken during the dormant season, typically from mid-autumn to early spring. The cuttings should be about six to eight inches long and include a terminal bud. The cuttings are then planted in well-draining soil and kept in a humid environment. Rooting typically occurs within eight to twelve weeks.
Grafting Propagation
Grafting of Fraxinus americana L. var. crassifolia Sarg. is typically done in early spring before the buds begin to open. A scion from the desired plant is grafted onto an established rootstock of a closely related species such as Fraxinus pennsylvanica or Fraxinus velutina. The graft union is then wrapped with grafting tape and kept in a humid environment until the graft is successful.
Disease Management
Fraxinus americana L. var. crassifolia Sarg. is susceptible to various fungal and bacterial diseases. The most common disease affecting this plant is ash yellows, caused by a phytoplasma that disrupts the plant's normal growth processes. Symptoms include yellowing of leaves, stunted growth, and premature leaf drop. The disease is spread by leafhoppers and can be managed by removing infected trees and controlling the spread of leafhoppers through insecticide applications.
Another common disease is ash rust, caused by the fungus Puccinia sparganioides. It leads to the formation of yellow or orange rust lesions on leaves, which eventually turn black and fall off. The disease can be managed through good sanitation practices such as cleaning up fallen leaves and removing infected branches. Fungicide applications may also be necessary to control the spread of the disease.
Ash anthracnose is caused by the fungus Discula fraxinea and is characterized by the development of brown spots on leaves, which can eventually lead to defoliation. The disease is most severe in cool, wet conditions and can be managed through proper pruning to improve air circulation and reduce moisture on leaves. Fungicide applications may also be necessary to control the spread of the disease.
Pest Management
Fraxinus americana L. var. crassifolia Sarg. is also susceptible to various insect pests. The most common pest affecting this plant is the emerald ash borer, a beetle that burrows into the tree's bark and disrupts its internal flow of fluids. Infested trees show symptoms such as thinning of the crown, increased woodpecker activity, and the appearance of D-shaped exit holes. The pest can be managed through early detection and removal of infested trees as well as the use of insecticide applications.
Another common pest is the ash flower gall mite, a microscopic pest that causes the formation of small, round galls on the tree's leaves. Although the galls are unsightly, they rarely cause significant harm to the tree. However, severe infestations can lead to reduced growth and premature leaf drop. Management options include pruning off heavily infested branches and improving the overall health of the tree through proper fertilization and irrigation.
Finally, the ash plant bug is a common pest that feeds on the tree's leaves, causing distortions and ultimately leading to defoliation. Management options include the use of insecticides and the removal of heavily infested branches.
