Common Fire Chief Arborvitae Problems and How to Fix Them

The Fire Chief Arborvitae, with its distinct globe shape and dynamic foliage, is a popular shrub. Its appeal lies in the year-round color it provides, shifting from golden-yellow in the spring to deep orange and red hues in the cooler months. While known for being low-maintenance, it can be susceptible to certain environmental pressures and horticultural issues that may affect its health and appearance.

Common Causes of Browning

One of the most frequent concerns is the browning of the shrub’s foliage. Winter burn, a form of desiccation, occurs when the plant loses more moisture through its needles from sun and wind than it can absorb from frozen ground. This condition results in dry, brown foliage, particularly on the side of the plant exposed to harsh winter winds. Protecting the shrub with a temporary windbreak, like a burlap screen, can mitigate this moisture loss.

Drought stress is another cause of browning, especially during hot, dry summer periods. When water is scarce, the plant cannot transport enough moisture to its needles, causing the tips to turn brown. Intense summer sun can also lead to sun scorch, which presents with similar browning symptoms as the foliage is burned by the heat and light.

Not all browning is a sign of a problem; arborvitae undergo a natural shedding process. In the fall, the innermost and oldest needles will turn brown and drop off the plant. This is a normal part of the plant’s life cycle. This natural needle drop can be distinguished from other problems because it occurs uniformly on the inside of the shrub, while the outer foliage remains healthy.

Identifying Pest Infestations

Insect infestations can lead to foliage damage and discoloration.

Spider Mites

Spider mites are a common pest due to their tiny size. These pests suck sap from the needles, causing a stippled or speckled appearance that can make the foliage look yellow or bronzed. A tell-tale sign of their presence is fine webbing between the branches, and infestations worsen in dry, dusty conditions.

To check for spider mites, hold a white piece of paper under a branch and tap it; the tiny mites will fall and be visible as slow-moving specks. A forceful spray of water can dislodge a small population. For more persistent issues, insecticidal soaps or horticultural oils can be effective, but do not apply them in full sun or high heat.

Bagworms

Bagworms are identified by the cone-shaped bags they create from silk and foliage. These caterpillars feed on the needles, and a heavy infestation can strip a shrub of its foliage. For small numbers, manually pick the bags off the branches and destroy them before eggs hatch. For larger infestations, treatments with Bacillus thuringiensis or Spinosad are effective on young larvae.

Arborvitae Leafminers

Arborvitae leafminers are moth larvae that burrow into foliage tips. This tunneling causes the tips to turn brown, with damage most noticeable in the spring. Pruning and disposing of affected brown tips in early spring helps control the population by removing larvae before they mature.

Diseases Affecting Fire Chief Arborvitae

Fungal diseases can affect the health of a Fire Chief Arborvitae, often taking hold when the plant is already stressed.

Tip blight is a fungal disease that causes the tips of the needles and small branches to turn brown and die back. This condition is caused by fungi like Pestalotiopsis or Phyllosticta, which thrive in wet, mild weather and infect plants weakened by stress. The fungi produce tiny black spore-producing structures on the dead tissue, which can spread spores via wind and water.

Distinguishing tip blight from winter burn can be done by looking at the symptoms, as infections start at the tips and progress down the branchlets. Management involves pruning out and destroying the infected branches. Fungicides are not usually necessary but can be used as a preventative measure.

Root rot occurs when soil is consistently waterlogged from poor drainage. Compromised roots cannot absorb water, leading to foliage turning brown from the bottom of the shrub upwards. The plant may also look wilted even in moist soil.

Infected roots will appear dark and mushy. Prevention by ensuring the planting site has excellent drainage is more effective than treatment. If suspected, reduce watering and allow the soil to dry out, but advanced cases may not be salvageable.

Preventing Problems with Proper Care

Proactive care is the best strategy for avoiding common issues. Select a site that receives full sun to partial shade, as sufficient sunlight promotes the most vibrant foliage colors. When planting, dig a hole that is two to three times wider than the root ball but no deeper.

The shrub should be placed in the hole so that the top of the root ball is level with or slightly above the surrounding ground. Planting too deeply can lead to the base of the trunk staying too moist, which encourages decay. Backfilling the hole with a mix of native soil and rich garden soil provides a good start.

Fire Chief Arborvitae is adaptable to various soil types but performs best in soil that is moist yet well-draining. Heavy clay soils that retain a lot of water can lead to root rot, so amending these soils is advisable. Good drainage ensures that the roots have access to oxygen.

A consistent watering schedule is important for newly planted shrubs. Water deeply one to two times per week for the first growing season to encourage a deep root system. Once established, the shrub is more tolerant of dry conditions but will benefit from watering during extended heat. Apply a two- to three-inch layer of mulch around the base to retain soil moisture.