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Joseph F. Boggs, Ohio State University Extension, Hamilton County/Southwest District; James A. Chatfield, Erik A. Draper, |
Shifting Treeage Categories
Treeage categories are not static. This is particularly true of Category 3 plant problems. In simplest terms, assigning a plant problem to Category 3 means that some action can and should be taken. However, Treeage practitioners should strive to select actions that ultimately move the problem out of Category 3 and into Category 1, where no action is necessary, or to address the plant problem in a way that the problem is completely eliminated. Conversely, if no action is taken, sometimes Category 3 problems may become Category 2 tragedies.
A young tree that is planted too deep should be placed in Treeage Category 3. The treatment is straight forward and needs to be applied only once the tree should be excavated and replanted to the correct depth. Once this is accomplished, the problem is solved, and the tree is taken off the Treeage chart. However, if nothing is done, this Category 3 problem may eventually sink into the irretrievable realm of Category 2.
Apple scab on crabapple is clearly a Category 3 disease on susceptible varieties. If left alone, susceptible trees may become completely defoliated during years when fungal infection is heavy. Successive years of heavy defoliation may weaken trees. Multiple, properly timed applications of fungicides may suppress the problem, but a better long-term solution would be to select disease-resistant crabapple cultivars.
The availability of pest- and disease-resistant plant cultivars illustrates that certain pest-management solutions can be used to shift a problem from Category 3 into Category 1. Apple scab is a Category 1 problem on disease-resistant crabapple cultivars since nothing needs to be done.
A company's pest management capabilities can play a significant role in the placement of pest problems into certain categories. Remember that the definition of a Category 2 problem is that the plant will not thrive or survive with the application of the best available intervention efforts. The operative words are "best available." What if a company simply lacks the necessary equipment to successfully treat a particular problem? Not all hospital emergency rooms are equipped the same way, and some patients live or die based on this disparity in lifesaving equipment.
Treeage Categories generally focus on plant health care. However, there remains the practical need to consider aesthetics. Fall webworm, Hyphantria cunea, envelops leaves in large silken nests, but on most landscape trees, their late season depredation causes little or no harm to the overall health of the tree. They are a Category 1 pest problem based on plant health care. However, if these nests should shroud the branches of a specimen weeping cherry tree, the customer will certainly want something to be done based on aesthetics. The pest problem shifts to Category 3.