These living agents may build up on trees weakened by noninfectious agents and threaten the health of nearby trees. Superficially, the symptoms of noninfectious diseases may resemble those produced by insects or fungi. If no signs of these organisms are present, the tree may have been affected by one of the agents described here. Even if signs of fungi or insects are present, a nonliving agent may be the underlying cause of your tree's problems. In most cases, prevention is the key to minimizing injury.
Leaf margins turn yellow or brown and leaves fall prematurely.
Water during periods of hot weather to prevent injury to smaller trees. Plant trees in locations protected from prolonged exposure to sun and wind. An early fall or late spring frost when trees are actively growing can injure or kill succulent stem tissue, leaves, and buds. Most trees can survive this injury, but their growth rates are reduced. Plant tree species adapted to local conditions.