Needled evergreens are an important component of any yard's overall look. This is especially true in winter. When most other plants are bare and brown, evergreens add bright color and gentle motion to the landscape. Tip blights affecting the needles and branch tips of pines, arborvitae, cypress, fir, redwood and junipers are caused by a variety of pathogens. Identifying the cause of the problem is essential to choosing an appropriate treatment to bring the tree back to good health.
Also known as Diplodia blight, this fungus mainly attacks pine trees (Pinus spp.), but it can also appear on other coniferous species. Symptoms are likely to show up on only one side of the tree or on the lower branch tips, where needles turn brown from base to tip. Needles may curl or become deformed, and new candles, or beginning branches, may droop. Resin can seep from the base of diseased needles or from wound sites where infection has invaded the tree. Pruning away infected twigs and cones and disposing of the cuttings away from the yard helps reduce the spread of disease. Avoid pruning in wet weather, and sanitize pruning tool blades with rubbing alcohol between each cut. Spraying with a fungicide containing potassium bicarbonate can help prevent and treat the disease. Spray when buds first begin to swell, repeat when new needles begin to emerge and spray again 10 to 14 days later. White pine (Pinus strobus), which grows in U.S. Department of Agriculture plant hardiness zones 3 through 8, and most species of spruce (Picea spp.), are resistant to diplodia tip blight.
Phomopsis Tip Blight
Phomopsis usually infects the tips of juniper (Juniperus spp.) plants and other evergreen trees' branches from late spring to fall, turning the needles reddish or brown. As the disease progresses, the foliage turns gray. Plant growth may be stunted and needles may be deformed into witches' brooms, a type of slow-growing branch cluster. Plant evergreens far enough apart to allow for good air and sunlight penetration between plants. Keep the foliage dry by watering at ground level only, pruning plants to increase air circulation and cutting back nearby plants that shade the junipers. When the weather is dry, cut out diseased areas of the plant with sanitized clippers and destroy the cuttings. Copper-based fungicides applied at intervals of one week to three weeks in spring should control Phomopsis. Follow label directions for spraying amounts and methods.
Kabatina Tip Blight
Although no fungicides are available to treat Kabatina tip blight, which primarily attacks junipers, the disease rarely kills. Kabatina appears in early spring, turning branches red or yellow and the needles dry and brown. Proper sanitation, pruning and planting as described for control of Phomopsis can help control Kabatina. Choose resistant juniper species such as "Robusta Green" (Juniperus chinensis "Robusta Green"), which grows best in USDA zones 5 through 9.
Pestalotiopsis Tip Blight
Appearing mainly on arborvitae (Thuja spp.), this disease usually infects injured or weakened trees. Symptoms appear at the tip of the needles and spreads towards the base. The foliage turns yellow, then dark brown to black, making the tree appear scorched. Twigs may develop pimple-like fruiting surfaces. Pruning dead or diseased areas or pruning to improve air circulation keeps the disease from spreading. Fungicides containing copper may be sprayed in early spring to protect the trees from infection. Keep trees healthy and avoid injuring the trees with gardening tools to help them resist and withstand tip blight disease.
- Missouri Botanical Garden: Needlecasts and Evergreen Tip Blights
- Cornell University Extension: Diplodia Tip Blight
- University of Illinois Extension: Kabatina Tip Blight
- Ohio State University Extension Fact Sheet: Phomopsis and Kabatina Tip Blights of Junipers
- University of Illinois Extension: Phomopsis Tip Blight
- Missouri Botanical Garden: Pestalotiopsis Tip Blight on Arborvitae
- University of Rhode Island Extension: Fact Sheet -- Diplodia Tip Blight
- University of Minnesota Extension: What's Wrong With My Plant? Spruce > Trunk or Branches > Witches’ Broom
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