Maple (scientific name Acer) is a group of trees that offers unbeatable landscape value and are prized for their range of fall colors, from brilliant red and purple to glowing gold. While many traditional hardwood trees fall prey to serious and even pandemic disease, maples, while not without their own set of problems, generally stand strong against pest invaders and disease.
Anthracnose and leaf spot are fungal diseases that affect the tissues of the leaf. The telltale signs are brown, dried lesions, usually on the leaves or along the leaf vein. It can also affect flower parts, fruit and stems. Some people say the disease looks like scorch from a flame or heat. These diseases spread by fungal spores spread during rainy seasons and in moderate weather trends.
Anthracnose usually affects sugar, silver, Norway and sycamore maples the hardest; it may also invade the nuisance plant box elder. If you suspect your tree has been infected, contact your local county extension agency for proper treatment in your region.
Silver, Norway, sugar and red maples are most affected by this fungal infection, but by no means is it exclusive to Maples. Verticillium attacks thousands of species worldwide, and certain groups of plants have natural immunity. Verticillium can be acute, intensely affecting the whole plant or just one limb; or it can be chronic, returning sporadically year after year. Key signs include curling, drying, abnormal coloration, wilting and death.
Symptoms usually appear in early summer to late fall. Some plants will die rapidly from an infection and others will only show infection in one branch. The verticillium fungus enters the tree from the roots or fresh wounds. The best way to avoid verticillium is to choose maple trees that are not affected, such as Acer triflorum (Three Flower maple) or Acer japonicum (Japanese maple).
Leafhoppers can cause serious harm to an otherwise beautiful tree. This insect feeds on many types of trees but has an affinity for red maple. The bug is very tiny (3-15 mm) and are usually a bright yellowish green, but color does vary. They feed on the foliage and cause a white dotted pattern, called stippling. Browning and leaf stunting can also occur Look for the pest on the undersides of the stippled leaf or for stunted growth and yellow leaves.
Always use the appropriate amount of fertilizer, because over-feeding can actually increase leafhopper populations. Chemical control with a systemic insecticide is useful. Spray where the plants feed on new and young growth. Try planting resistant maple varieties such as Acer rubrum (‘Autumn Blaze’).