If the majority of needles are infected for 3 to 4 years in a row, the branch will die. Rhizosphaera needle cast is a fungal disease of spruce trees that causes needles to turn brown and fall off. Remember, the label is the law. Clean up and dispose of fallen needles before spring growth begins. Infected needles, including those that are still attached to branches and those that have fallen to the ground, produce spores that can be blown or splashed to healthy needles. Inspect the depth of the mulch layer each year. This shedding of needles can be more serious to conifers than losing leaves is to deciduous hardwoods. University of Minnesota Extension discovers science-based solutions, delivers practical education, and engages Minnesotans to build a better future. At M&M Tree Care, we’ll treat the tree for the fungus over the course of two years. Trees can be protected from Rhizosphaera needle cast with properly timed fungicide applications. Leave at least a 2 inch space between the mulch and the trunk to allow for air movement. Treating Rhizosphaera Needle Cast should always be done by a professional arborist. Before spraying fungicide, send a lab sample to the UMN plant disease clinic to confirm that Rhizosphaera is responsible for the damage. Steve Nix is a natural resources consultant and a former forest resources analyst for the state of Alabama. The symptoms of needle cast first appear on needles as light green to yellow spots, which eventually turn red or brown. Use a magnifying glass to look closely at both green and discolored needles. Apply a fungicide labeled for this disease, following label directions. Needle infection occurs best during warm (77 F) wet weather. All rights reserved. To enhance the effectiveness of the fungicide mix with Nature's Own Spray Helper. Needle cast diseases cause spruce trees to “cast off” their older needles and keep only the young needles at the tips of the branches. However, Christmas tree growers must take some action against the disease. Prevention and Control of Common Conifer Tree Diseases, Needle Blight Tree Disease - Identification and Control, Diagnosing and Controlling Heart Rot in Trees, Common Hardwood Tree Diseases - Prevention and Control, Leaf Spot Tree Disease: Prevention and Control, Identifying and Controlling Powdery Mildew on Trees, Preventing and Controlling Sooty Mold Tree Disease, Use Needles to Identify Common North American Coniferous Trees, Leaf Scorch Tree Disease - Prevention and Control, B.S., Forest Resource Management, University of Georgia. If control is desired for cosmetic reasons, protection of newly emerging needles through June with regular applications of an appropriate fungicide may be helpful. Plant spruce trees on sites with acidic, moist, well drained soils and full sun. Norway spruce (P. abies) is relatively resistant but can become infected when grown under stressful conditions. Tiny black fruiting bodies (spore producing structures) form on the surface of the needles before or after the infected needles are shed. Several other fungi result in symptoms very similar to Rhizosphaera. Needle cast seems to thrive when conifers are under stressful conditions including drought. These are the spore producing structures of the Rhizosphaera fungi. Discolored needles fall off in late summer to fall. Options include Norway spruce or Black Hills spruce. Extension is expanding its online education and resources to adapt to COVID-19 restrictions. Water in summer and fertilize in the spring to keep trees growing vigorously and prevent needle cast. Make a second application 3 to 4 weeks later. Growth of the fungal pathogen from the spots on the needle will cause the death of the entire needle. How do I save a tree or shrub with Rhizosphaera needle cast? Submit a sample to the UMN Plant Disease Clinic for testing. The tree becomes unattractive and may look as though it is dying, but don’t despair. These diagnostic tools will guide you step-by-step through diagnosing a plant problem or identifying a weed or insect. Growth of the fungal pathogen from the spots on the needle will cause the death of the entire needle. To control Needlecast on a tree that is already infected, prune severely infected branches. Tiny black bumps can be seen arranged in neat rows on infected needles. Another key characteristic of needl… As a result some chlorothalonil-based fungicides are listed as phytotoxic to spruce trees. He is a member of the Society of American Foresters. Young seedlings and saplings are susceptible, as well as pure and crowded stands. Avoid planting trees on sites not suited for a particular species. Chlorothalonil based fungicides may discolor spruce needles. White spruce (P. glauca, including Black Hills spruce) is somewhat resistant but can become infected when grown under stressful conditions. Do not shear spruce as shearing creates a dense, compact growth that stays wet longer. Avoid wetting needles watering the lawn. Two needle cast diseases occur in North Dakota: Rhizosphaera needle cast and Stigmina needle cast. The University of Minnesota is an equal opportunity educator and employer. Remove the bottom most branches from the trunk to help increase circulation around the tree canopy. We have much to learn about when these fungi attack a tree, how long the fungus must be in the tree before needles are shed, when is the best time to apply a fungicide, and which chemicals provide the best protection. Older needles can become infected if environmental conditions are highly favorable for disease. Do not overcrowd plants. © By mid to late spring the death of infected needles is well advanced giving diseased trees a red to brown "fire-scorched" appearance. During the spring, we’ll spray the tree with a copper-containing fungicide designed to … Add additional mulch only to maintain a 3 to 4 inch depth. White pines have fewer disease problems than Austrian or Scots pines. The symptoms of needle cast first appear on needles as light green to yellow spots, which eventually turn red or brown. Needle cast is a broad group of fungal diseases that cause conifers to shed needles. CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Rhizosphaera needle cast is caused by the fungus Rhizosphaera kalkhoffii. If the tree is in a landscape with a sprinkler irrigation system, make sure that water is not spraying the needles. Infected needles usually turn red to brown from their tips beginning in winter or early spring. Regents of the University of Minnesota. Colorado Blue Spruces are very susceptible to Rhizosphaera needle cast, but other types of spruce are more resistant. Plant Norway (P. abies) or white spruce (P. glauca) as they are more resistant to Rhizosphaera needle cast. Other evergreen options include concolor (white) fir, Easter red cedars or other junipers, and yew. Watch for reinfection. Needles are most commonly infected when they are young and still growing. The fungus survives winter on living and recently killed needles. Trees can be protected from Rhizosphaera needle cast with properly timed fungicide applications. Needle cast is a broad group of fungal diseases that cause conifers to shed needles. Treatments will not cure … Trees planted on poor sites are more likely to be infected with Rhizosphaera needle cast due to stressful conditions. Do not plant Colorado blue spruce (Picea pungens) or other spruce that are not well adapted to the environmental conditions in your area. Repeat the spray every 14 to 21 days, as necessary. 2020 Consider treating affected trees with fungicides containing the active ingredient copper (e.g., Bordeaux mixture) or chlorothalonil. Trees stressed from drought, poor planting practices or other factors are more likely to suffer from Rhizosphaera needle cast. Rhizosphaera and Stigmina, the two most common needle cast diseases of spruce trees, are treatable.