Insects

Asian longhorned beetle
A new and potentially serious threat to some of North America’s most beautiful and popular trees is the Asian Longhorned Beetle (Anoplophora glabripennis). Native to parts of Asia, the beetle is believed to have arrived in North America in the wooden packing material used in cargo shipments from China. Isolated Asian Longhorned Beetle infestations have been discovered in Brooklyn and Amityville, New York, and in Chicago, Illinois

Diseases

Anthracnose
Anthracnose (Discula spp., Kabatiella apocrypta) is a name for a group of diseases caused by several closely related fungi that attack many of our finest shade trees. It occurs most commonly and severely on sycamore, white oak, elm, dogwood, and maple. Other host plants that are usually only slightly affected include linden (basswood), tulip tree, hickory, birch, and walnut.

Verticillium Wilt
Maple wilt, also called Verticillium wilt, is a common and serious disease of maples. The destructive soil-borne fungus, Verticillium, kills many maples each year throughout North America. Norway maples seem especially sensitive to infection by Verticillium. Silver, red, sugar, sycamore and Japanese maples are also susceptible.

Sapstreak disease of sugar maple
Sapstreak disease, caused by the fungus Ceratocystis coerulescens, is a serious threat to sugar maple forests. Although the disease is causing only minor damage at present, it has the potential to become an important problem. Sapstreak is a fatal disease; infected trees do not recover. In addition, timber salvage value is low because the wood is discolored.

Tar Spot
These dramatic but inconsequential diseases of numerous maple species cause small to almost one-inch diameter tar-like spots on leaves. The fungus overwinters on fallen leaves, then infects the upper surfaces of leaves in spring during moist conditions.  Usually the best approach is to do nothing.  Cleaning fallen leaves in the autumn can help reduce the amount of fungus that overwinters.