Disease Transmission and Spread:
Tree disease is transmitted by vectors (or disease agents) using two major avenues of spread - the soil/root avenue and the wind/insect avenue. Insects and wind carry many of these pathogens from tree to tree. Soil-borne organisms move pathogens through soil moisture, taken up by tree roots and spread by root grafts to other trees.
Stimulants Increase Tree Disease Problems:
Windstorms, ice and mechanical injury break tree bark's protective cover and opens the way for tree decay. Drought causes tree stress and can weaken trees to disease over that period. Too much water cuts down on oxygen and can attract root rotting organisms.
Prevention of Tree Disease:
Know your tree diseases and their method of spread. Removing tree parts, removing the disease agent (vector) and chemical treatments can help with prevention. Managing you tree for optimum health goes a long way.
Amillaria Root Rot - spreads root to root, from host to root grafted neighbor.
Dutch Elm Disease - spread by both elm bark beetle and root to root.
Oak Wilt - spread root to root, from host to root grafted neighbor.
Chestnut Blight - spread by endemic disease spores through bark wounds on host.
Anthracnose - spores windblown or splashed by rain on new leaves of host.
Common Diseases and the way they spread:
Controlling Tree Disease:
Using indirect methods is the best way to control tree disease. You must have a tree or timber management program that includes fire control (fire damage undermines tree bark), avoiding single tree species planting and using disease resistant trees.