• Maples (Acer spp.) belong to the Aceraceae plant family and are deciduous or evergreen trees that come in varying sizes. The trees are best adapted to the cooler climates and do not grow well in areas with warm temperatures or the desert regions. Maples are susceptible to a number of disorders, physiological or pest related, that can cause yellowing and discoloration of foliage. Maples adapt to full sun or partial shade and prefer a moist root zone.
  
  

Scales

• The University of California Extension lists scales as a potential pest of maple trees. Scale damage is characterized by the wilting and yellowing of foliage followed by premature leaf drop. The insects often curl the leaves and cause discoloration and blemishing on twigs and leaves. Scales are often missed due to their immobile, wingless and headless bodies. Only the male scales have a very small pair of wings but they live for a few hours and do not feed. The females damage trees by sucking fluids with their strawlike mouths. Control scales by introducing natural predators like mites and lacewings in trees. Chemical control options include the use of carbaryl and malathion.
  
  

Mites

• Mites are small, dot like insects belonging to the spider and tick family. The insects are cited as a potential pest of maples by the University of California Extension site. Mite infestation in maple is characterized by the appearance of very small dots on the foliage followed by a bronzing as the insects suck the fluid from the leaves. The damaged foliage eventually turns yellow and starts to drop. Maple trees that are not getting enough water are most susceptible to mites. Given their small size, the insects are hard to detect and the yellowing foliage is often the first indication of a problem. Control mites with natural predators like minute pirate bugs, bigeyed bugs and lacewings. Recommended chemicals include insecticidal soaps and oils.
  
  

Sunburn

• Sunburn is cited by the University of California Extension site as a problem in maple trees that is characterized by yellowing of foliage. Sunburn, also referred to as sunscald or leafscorch, is caused by an excess or deficiency of light in trees where the affected foliage starts to brown and yellow. The discoloration is followed by the death of the leaves between the veins. Sunburn also affects the tree trunk, leading to darkening, cracking and appearance of sunken areas that become highly susceptible to wood-boring insects and wood rotting fungi. Management includes proper tree care and planting in adaptable sites. Avoid excessive pruning of crown, and water adequately.