July 14, 1995
Protecting Roots of Mature Trees
Trees are important fixtures in the urban and rural landscape. We value above-ground parts of trees for their spring flowers, cooling shade in summer, and vibrant leaf colors. But healthy root systems below ground are vital for tree vigor and longevity. Roots are responsible for water and mineral nutrient uptake, energy storage, and anchorage. If for any reason tree roots are damaged, tree health will be jeopardized.
Honeysuckle Leaf Blight
Honeysuckle samples showing a fungal leaf blight disease have been arriving in the Plant Disease Clinic during the past few weeks. The disease, caused by the fungus Insolibasidium deformans, first appears in the spring. Initially, the undersides of infected leaves show a silvery- white discoloration, usually in spots bound by the leaf veins. As the disease progresses, brown areas develop, often involving large portions of the leaves. Infected leaves eventually become entirely brown and distorted and fall prematurely.
Powdery Mildew of Rose
Powdery mildew is a widespread disease of roses. The disease is easily recognized by the white powdery appearance of infected leaves, twigs, and flower buds. Infected leaves may also appear distorted and fall from the plant.
Powdery mildew is favored when rainfall is low or absent, temperatures are between 70 and 80, nighttime relative humidity is high, and daytime relative humidity is low. Mildew spores can spread easily by wind to nearby healthy plants.
To control powdery mildew: