Needle Cast is a fungus that affects conifer trees causing infected needles to become discolored and die and eventually be cast from the tree. Begin scouting for this disease in early April before bud break. Scout on slightly overcast days as opposed to sunny ones, as it will make the discoloration of the needles stand out much better. Examine needles near the base of the tree first, as this is where infection is most likely to occur. Infected needles will have one or more purplish-brown bands or spots, which are evident on both the upper and lower surface of the needle. Usually just before bud break, the banded areas will begin to swell and split open lengthwise on the undersurface of the infected needles, in preparation for releasing infectious spores. Once the fruiting bodies rupture, spongy, orange, spore-bearing fungal tissue will protrude from the undersurface when conditions are damp. When this tissue begins to turn black, spore production and dissemination is complete. Three fungicide applications are generally recommended. The first should be made when at least 50% of the buds have broken and the new growth is 1/2 inch long. Make two more applications at two to three week intervals after the first. To help prevent the spread of this disease, plant where there will be good air drainage, and keep properly pruned to encourage airflow between the trees.
Powdery Mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of fungi in the order Erysiphales. It is one of the easier diseases to spot, as its symptoms are quite distinctive. Infected plants display white powdery spots on the leaves and stems. The lower leaves are the most affected, but the mildew can appear on any above-ground part of the plant. As the disease progresses, the spots get larger and denser as large numbers of asexual spores are formed, and the mildew may spread up and down the length of the plant. Proper fertilization and fungicide applications will help to suppress and/or prevent some outbreaks.