Maintain a 3 to 4 inch deep, even layer of wood chip mulch around your tree to prevent weed growth. Remove the bottom most branches from the trunk to help increase circulation around the tree canopy.ĭo not shear spruce as shearing creates a dense, compact growth that stays wet longer. Use the mature size of the tree as a spacing guide when planting. Maintain good air circulation around treesĭo not overcrowd plants. These plants are likely to be best adapted to the local conditions. Whenever possible plant spruce trees grown from local seed sources. Trees planted on poor sites are more likely to be infected with Rhizosphaera needle cast due to stressful conditions. Plant spruce trees on sites with acidic, moist, well drained soils and full sun. glauca) as they are more resistant to Rhizosphaera needle cast. ![]() New needles remain green, while old needles turn brown on a spruce infected with Rhizosphaera needlecast Plant disease tolerant treesĭo not plant Colorado blue spruce ( Picea pungens) or other spruce that are not well adapted to the environmental conditions in your area. abies) is relatively resistant but can become infected when grown under stressful conditions. glauca, including Black Hills spruce) is somewhat resistant but can become infected when grown under stressful conditions. Trees affected by Rhizosphaera needle castĬolorado blue spruce ( Picea pungens) is highly susceptible and is commonly affected. Submit a sample to the UMN Plant Disease Clinic for testing. Lab analysis is necessary to distinguish Rhizosphaera needle cast from other diseases of spruce trees. If the majority of needles are infected for 3 to 4 years in a row, the branch will die. Infected trees have few needles near the trunk and look thin, or see-through.ĭamage typically starts on the lower branches and moves up the tree. These are the spore producing structures of the Rhizosphaera fungi.ĭiscolored needles fall off in late summer to fall. Tiny black bumps can be seen arranged in neat rows on infected needles. Use a magnifying glass to look closely at both green and discolored needles. In spring or early summer, new needles at the branch tips are green, and the older needles turn brown to purple. For preventative control of common diseases, use Liqui-Cop to complete cover plants to lessen the chances of infection.Young tree with a thin canopy due to Rhizosphaera needle cast This product is highly weather-resistant and does not need to be applied with oil or a surfactant. It is also an effective method of preventing and treating cold damage in palm trees and can provide protection against light frosts in many plants. ![]() Copper based, it effectively controls diseases such as anthracnose, bacterial leaf spot, fireblight, and botrytis among many others. Liquid Copper Fungicide Spray is a key tool in disease prevention and treatment on a large variety of trees, citrus, nuts, vegetables and more. The lower rate is suitable for general preventive sprays under normal conditions.
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