Origin
Acer negundo L. var. californicum (Torr. & Gray) Sarg., also known as California box elder, is a subspecies of Acer negundo, a deciduous tree species native to North America. The subspecies is indigenous to western North America, particularly California and Oregon.
Common Names
California box elder is also commonly known as California maple, ash-leaved maple, box elder maple, and western box elder.
Uses
The California box elder is not a major source of timber, but it is sometimes used for manufacturing crates, boxes, and other small wooden items. Its sap can be processed to make syrup, although it is not as commonly used as the sap of sugar maple. In some cultures, the California box elder has traditional medicinal uses.
General Appearance
The California box elder is a medium-sized tree that can grow up to 10-25 meters tall, with a trunk diameter of up to 70 centimeters. The tree features compound leaves made of three to five individual leaflets that are green in color and have toothed edges. The flowers of the California box elder appear in the spring and are usually yellow-green in color. The tree's fruit, which is known as a samara, is winged and shaped like a V. The bark of the California box elder is gray and smooth when the tree is young, but it becomes rough and scaly with age.
Growth Conditions for Acer negundo L. var. californicum (Torr. & Gray) Sarg.
Acer negundo L. var. californicum (Torr. & Gray) Sarg., commonly known as the California Box Elder, is a deciduous tree that is native to western North America. This plant species typically grows in riparian ecosystems, floodplains, and wetlands with well-drained soils. It is tolerant of a variety of soil types but prefers sandy or loamy soils.
Light Requirements
California Box Elder requires partial to full sun for optimal growth. It can tolerate shaded areas, but its growth rate may slow down, and the plant may become leggy. Therefore, it is recommended to plant this tree in an area where it can receive at least six hours of direct sunlight daily.
Temperature Requirements
This tree species is known for its ability to tolerate a wide range of temperatures. It can withstand both high and low temperatures, with the ideal temperature range for growth being between 50-90°F (10-32°C). California Box Elder is hardy in USDA zones 6-9 and can tolerate temperatures as low as -5°F (-20°C) in winter.
Soil Requirements
The California Box Elder prefers well-drained soils that are rich in organic matter. It can grow in a wide range of soil types, including clay, loam, and sandy soils. However, the plant does not do well in soils that are waterlogged for an extended period. Additionally, this species prefers a slightly acidic to neutral soil pH (between 6.0-7.5).
It is worth noting that young California Box Elders need sufficient moisture to establish and grow effectively. Once established, the plant can tolerate periods of drought.
Cultivation Methods
Acer negundo L. var. californicum (Torr. & Gray) Sarg. can be grown outdoors in full sunlight or partial shade. It thrives in well-drained soil that is rich in organic matter. The plant can be propagated from seed or cuttings. It is important to plant the tree in a location with enough space for it to grow, as it can reach up to 50 feet in height.
Watering Needs
Young Acer negundo L. var. californicum (Torr. & Gray) Sarg. trees require regular watering until they establish a deep root system. Afterward, the plant can tolerate drought, but it is best to water it regularly during dry spells. It is better to water the tree deeply and infrequently rather than frequent shallow watering.
Fertilization
Acer negundo L. var. californicum (Torr. & Gray) Sarg. benefits from fertilization. A slow-release fertilizer can be applied at the beginning of the growing season to provide the nutrients necessary for healthy growth. However, it is essential not to over-fertilize the plant, as this can lead to excessive growth and weak branches.
Pruning
Pruning Acer negundo L. var. californicum (Torr. & Gray) Sarg. is essential to maintain its shape and promote healthy growth. It is best to prune during the dormant season in late winter or early spring. The tree's interior, dead or damaged branches, and branches that cross or rub against each other should be removed. Care should be taken not to remove more than one-third of the tree's canopy in any one pruning session.
Propagation of Acer Negundo L. var. Californicum
Acer Negundo L. var. Californicum (Torr. & Gray) Sarg. can be propagated through multiple methods, including seed propagation, cuttings, and grafting.
Seed Propagation
Seeds for Acer Negundo L. var. Californicum can be collected in the autumn months, when they have turned brown and are ripe for harvesting. The seeds should be sown in the spring as soon as possible after collection, as they have a short viability period. The seeds will require a period of cold stratification for several weeks to simulate winter conditions before they germinate. The seeds can be sown in a seedbed or individual pots and gradually acclimated to more sunlight as they grow.
Cuttings
The cuttings method involves taking stem cuttings from a mature Acer Negundo L. var. Californicum plant and rooting them in a suitable growing medium. The cuttings should be taken in the late spring or early summer months when new plant growth is occurring. The bottom of the cutting should be dipped in rooting hormone to encourage root growth and then planted in a mix of perlite and peat moss. The cuttings can be covered with a plastic bag to maintain high humidity levels and placed in a spot with bright, indirect light.
Grafting
Grafting involves taking a stem or branch from a mature Acer Negundo L. var. Californicum plant and attaching it to the rootstock of another plant of the same species. This method is typically used to propagate specific cultivars or to improve the overall health of the plant. The graft should be completed in the spring when the plant is actively growing. The graft union should be wrapped tightly with grafting tape to prevent it from drying out until it has healed and the two plants have fused together.
Disease Management
Like any other plant species, Acer negundo L. var. californicum is also prone to develop some plant diseases. Some of the most common diseases that may affect the plant include verticillium wilt, powdery mildew, and anthracnose.
Verticillium wilt, caused by the fungus Verticillium spp., is characterized by yellowing and wilting of leaves and branches that eventually leads to death. Removing infected parts of the plant and using fungicides can help manage the disease.
Powdery mildew, caused by the fungi Erysiphe spp., is characterized by the presence of a white, powdery substance on the leaves. To prevent this disease, plant the Acer negundo in an area with good air circulation and sunlight or use fungicides.
Anthracnose, caused by the fungi Apiognomonia veneta and Glomerella cingulata, is characterized by the presence of brown or black spots on leaves that eventually leads to leaf drop. Managing the disease includes removing infected plant parts, fertilizing to promote overall plant health, and using fungicides.
Pest Management
Several pests also affect the growth and health of Acer negundo L. var. californicum. Some of the most common pests include aphids, spider mites, and borers.
Aphids are small, soft-bodied insects that suck sap from the plant, causing wilting and leaf curling. To control an aphid outbreak, use biological controls like ladybugs or use insecticides.
Spider mites are tiny insects that feed on the plant's fluids, leading to yellowing and the presence of webs. Using a forceful spray of water or insecticides can help manage an infestation.
Borers are the larvae of various types of beetle species that burrow into the bark of the tree, leading to stunted growth and death. Preventing infestations involves keeping the tree healthy, removing any diseased bark or branches, and using insecticides.
