• Deciduous trees are at risk of catching certain diseases.Autum image by Jazz Cortes from Fotolia.com
  
  Deciduous trees are trees that lose their leaves in autumn. Belonging in this classification of trees are oaks, ashes, elms, dogwoods, maples, cottonwoods and more. Like most plants, deciduous trees are susceptible to certain diseases. Oak leaf blister and tar spots of maple are two diseases that aren’t considered serious threats. However, verticillium wilt and heart rot could kill a tree.
  
  

Oak Leaf Blister

• As the name suggests, this disease affects the leaves on oak trees, both red and white. Spores that carry this disease live on tree buds through the winter and attack the leaves in spring when they open. Blistery, yellow to greenish lumps form on the top of the leaves. These bulges brown as time passes. This disease may attack the leaves every spring; however, as trees mature, the leaves form a resistance. Rarely is a fungicide needed to control oak leaf blister.
  
  

Tar Spots of Maple

• Many species of maple trees are at risk of catching tar spots of maple. Fungi that cause this disease overwinter on maple leaves that dropped the previous fall. Fungi contaminate the leaves of the trees in spring, when conditions are damp. Though spots are initially yellow to green in color, they turn black by the middle of summer. These spots can be as large as one inch in diameter. Leaves may wither or drop because of this disease. Fungicide is usually not necessary. However, if a chemical control is needed, a fungicide containing triadimefon or mancozeb is recommended by the Ohio State University Extension.
  
  

Verticillium Wilt

• If a tree contracts verticillium wilt, it has a good chance of dying. Verticillium wilt is caused by a fungus that lives in the soil and travels up the tree through its root system. As it attacks, leaves can drop without wilting, or dry and remain attached to the branch. Whole branches are known to die and droop. Tree growth is impeded after being affected by the disease over a number of seasons. Trees at high risk include maples, elms and catalpas. Some trees have recovered with fertilization and pruning. If a tree does die from verticillium wilt, another cannot be planted in its place as the fungus thrives in the soil for many years. According to the North Dakota State University Extension, certain deciduous trees including birches, flowering crabapples and mountain ash are resistant to verticillium wilt.
  
  

Heart Rot

• Heart rot, which causes decay, enters trees through exposed wood. Mushrooms growing on tree trunks are an indicator that a tree has heart rot. According to North Dakota State University, heart rot fungi remains confined in the trunks of vigorous trees. However, once trees are weakened due to dire pruning or severe storms, the fungi advance and trees become hollowed, making them dangerous since a strong wind may cause them to fall. If trees are suspected of having heart rot, they should be checked by a local forester and handled appropriately.