People Pressure Disease (PPD) - People Pressure Diseases (PPD) are those diseases of trees caused by people and their activities. Trees can not move away from people. People are crowding the trees. If you have a tree problem near a home, or anywhere there are many people, over 90 percent of the time the cause of the tree problem will be the people and their activities. There will always be an insect or fungus on the tree, the tree will always have some dieback, and too often the complete blame for the tree problem will be put on everything but the people activities. Minor and major construction work near a house are causes of many tree problems. Check for new swimming pools, new walkways, leaks of natural gas, underground electric lines, spills of all types of liquids including gasoline from lawnmowers and snow blowers, over fertilization and over use of herbicides, new gardens and new lawns, soil changes and new land grading, long term effects of sandy materials used about house foundations, salt for deicing walks and driveways, roots cut for new walks and driveways, root injury caused by planting bulbs, compaction due to parking cars, and the list goes on. Be on alert for trees that have grown themselves into a shady spot. This is common with birches. Then the borers come. Or, some shade trees are planted in full sun, like dogwood. And, again the borers come. PPD does not strike suddenly. PPD takes time and by the time the problem is noted, it is usually too late for effective action. The best solution comes through awareness programs. People need to know that trees can endure only so much abuse. It is the responsibility of the professional tree person to make people aware of potential problems, and to make certain they do not repeat. It will not be easy. In once fertile forest the depletion by people of coarse woody debris is also a people pressure disease for the group or system.
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