Fungal diseases can cause severe damage to your Norway maple, a tree that provides abundant shade and mixed interest of dark green foliage and subtle springtime bloom to your home gardening space. Avoid infection and the need for diagnostic control by providing consistent care or, if infection occurs, act quickly to manage fungi for continued health of your Norway maple.
Norway trees kept vigorous have a much greater capacity for avoiding and recuperating from fungal disease than weakened or stressed trees. Grow your Norway maples in areas that offer full sunlight to light shade. Norway maples thrive in many types of soil provided that conditions are moist and extremely well drained, according to the University of Illinois Extension HortAnswers. Norway maples will tolerate dry soil but will not tolerate wet sites.
Anthracnose is a fungal disease of Norway maple trees. Caused by a wide variety of disease pathogens that thrive in high moisture levels, anthracnose spores are spread on wind and water, infecting leaves, buds and stems. Verticillium wilt is another fungal disease of the Norway maple caused by the fungal pathogens Verticillium albo-atrum and Verticillium dahliae. This disease thrives in cool soil conditions and invades plants through their roots. Plants in bloom and those with stressed roots are at a higher risk of infection, according to the University of Illinois Extension HortAnswers.
Fungal disease of Norway maples diminishes the overall health of your tree. Maples can fully recover from anthracnose infections if they are vigorous at the time of infection and tree death rarely occurs. Look for leaf and twig spots or abnormally shaped areas of dying plant tissue as a sign of disease. Verticillium wilt causes early leaf drop, discolored leaves that appear yellowed that wilt, curl, die and drop as well as branch dieback, according to the University of Illinois Extension HortAnswers.
Fungal diseases of Norway maples attack a wide array of other host plants. Be mindful of planting susceptible plants within the same gardening space, as this makes control of disease extremely difficult when pathogens continue to spread from plant to plant, creating widespread infection. Anthracnose hosts include sugar maple, silver maple, red maple and miyabe maple, as well as other species like black oak, sycamore, white ash and kousa dogwood. Verticillium wilt hosts include amur privet, burkwood viburnum, Korean barberry and mentor barberry. Both fungal diseases attack Japanese maple and amur maple.
For control of fungal disease in Norway maple trees, remove and destroy affected plant parts and debris to reduce the spread of disease. Fungicides are typically not suggested for anthracnose, according to the University of Illinois Extension HortAnswers. The best method of management is to improve the health of your tree. For verticillium wilt, the use of fungicides is rarely necessary; however, copper-based options as well as chemicals with the active ingredient thiophanate-methyl are effective. In extreme cases, contact your local county extension agent or a licensed professional to create a fungicide treatment program, as applications must be timed and performed accurately for reliable control.