Entering Costs and Staging your EAB Infestation (Costs and Infestation Stage)
In this section, you will fine-tune the calculator to match your local conditions and costs.
As the EAB Invasion Wave moves through your area trees die in a predictable manner. The table below helps you predict where you are in a 12 year cycle that describes the number of trees that have become hazardous due to EAB injury and require limb or entire tree removal. The second line describes the number of years until all trees are in this state. The third line describes the likelihood of detection.
Expected Progression of EAB Damaged Trees and Likelihood of Detection
|% Ash Trees Affected by EAB
|Years Until All Ash Trees Are Damaged or Lost to EAB
|Likelihood of detection
Staging the EAB Infestation
If you indicate that your forest does NOT have EAB, the Calculator assumes that EAB is present, but you can't detect it because you have <1% of your trees with limbs damaged by EAB. At this level, (<1 out of 100 trees) it is hard to distinguish EAB decline from other sources of urban tree mortality. Based on the table above, the calculator assumes you have 8 years until all ash trees are lost.
If EAB has not yet been detected in your county (within 15 miles) enter your best guess as to when it will. The default value of 1 assumes 8 years until all trees are lost.
If you indicate that EAB is present in your city, use the table below and your estimate of the percentage of trees that lost more than half their canopy to EAB in order to see where you are in the EAB invasion wave. Two of the management options, Remove Unsafe Ash, and Replace Unsafe Ash use this your estimate from this table of the number of years you are into the infestation to simulate the proportion of trees to be removed and replaced in a given year.
How long will you aggressively protect your trees from EAB? Default value is 12 years to reflect the time it takes from when 1% of trees are beyond saving until all of the remaining ash trees are completely dead and unable to feed EAB larvae.
Duration of Pre-planned Removals
Enter the number of years you will take to cut down and remove ash trees that you plan to remove and not protect. If you live in an EAB infested city where ash trees are beginning to die you should plan to remove all your trees so that they are removed before they are lost to EAB. Use the last column in the above chart enter the duration in years. If EAB is within 15 miles and no ash trees are damaged you should enter 8 years. If you have 8% of your trees damaged you should enter have 4 years to remove.
Mortality of Treated Ash Trees
When EAB reaches your urban forest all the untreated trees will be killed. Although most treated trees will survive, a small proportion of the trees that are treated will be killed by EAB due to insecticide failure. Just like initial mortality of transplanted replacement trees, the Calculator will only apply the ash treatment failure rate once to the entire group of treated ash trees. After that year, the Calculator applies the mortality of successfully treated ash trees each year to reflect the rate at which trees die from factors other than EAB.
The cost of treating an ash tree is based on its size. Size is measured as the diameter of the tree trunk in inches at 5 ft above the ground. It is expressed as DBH, or diameter at breast height in inches. Some insecticides must be applied each year, others every 2 years. For a discussion of tree longevity and pesticide use, please visit this web site.
After the EAB Invasion Wave has passed there will be few living EAB in the area because most of the remaining ash trees will be treated with insecticide. For this reason it may be possible to switch from an aggressive to a maintenance level of tree protection. During the maintenance mode you refrain from insecticide use until EAB populations rebound and begin to cause new damage.If your management plan applies emmamectin benzoate (Treeäge) every 2 years during the infestation, you should double this value to 4. If applying. Imidacolprid or dinotefuran annually, then triple this value to 3. The year at which you stage your EAB infestation will determine the number of years until you can switch from aggressive to maintenance mode.
Enter the cost you have been quoted to plant, stake and mulch a new tree after the ash tree has been removed.
Replacement Tree Mortality Rate
We assume that 5% of all trees planted will die within a year after planting.
Trees that survive their first year will have a lower rate of mortality. We assume that the mortality rate will drop tp 2%.
Both rates can be adjusted to account for expected rates in your city.
Removal costs vary widely. The calculator provides a cost schedule for removing ash trees and grinding stumps based on tree size (DBH), measured as the diameter at 4.5 ft above the ground. These estimates were made based on conversations with municipal arborists in Indiana during 2009. It is very likely that the real costs will differ in your community. Once you have a local estimate of tree removal and stump grinding costs for a size range (eg $11.15 per inch for trees with a DBH range of 3 to 6 inches) the cost for removing one 5" DBH tree and its stump would be:
• If this cost schedule is too high you can lower it by setting your adjustment factor to something less than 100%. For example, a 50% adjustment factor would cut costs in half.
$55.75 ( or 5 X $11.15).
• If this cost schedule is too low you can raise it by setting your adjustment factor to something greater than 100%. For example, a 200% adjustment factor would double costs. Due to hazards caused when dead limbs shatter when they fall to the ground, the cost of removing a dead tree can easily be twice that of removing a tree that is mostly living.
When making long-term financial decisions, a discount rate is used to determine the value of future expenses in today's dollars. A discount rate of 5% assumes that a land manager is paying future costs with money gained from savings accumulating 5% a year. For this reason, the future costs are discounted by the interest rate and are substantially less in today's dollars.
Private landowners, foundations and other entities should use a discount rate to allow you to project future costs in today's dollars. We suggest using a 5% discount rate for comparative purposes, unless you have a more accurate number.
For municipalities or other entities that are not able to invest their money may the discount rate is not applicable. Here we suggest you use the default value of 0%.