Dosing Considerations When Performing
Macro-Infusions
The purpose of macro-infusion is to provide enough chemical
so that it is evenly distributed throughout the entire crown
of the tree. If the dose is too high there may be a phytotoxic
reaction, and if the dose is too low infections may occur.
Dosage is determined by measuring the diameter of the trunk
at breast height (DBH). Trunk diameter alone, however, does
not always reflect the proper dose because it may not reflect
canopy development. Very few trees are open-grown in the urban
setting. Their canopy development has been influenced by the
proximity of buildings, other trees, power line clearance,
etc. Our experience in treating trees over the past 20 years
has taught us that proper dosing is an art as well as a science,
and it is a key to predictable results.
How to Dose Trees 1. Use the label rate for trees between 22" – 28"
DBH with average size crown and no major limbs missing. For
smaller trees, reduce the dose by 3% for every inch below
22" DBH.
2. For trees with significant canopy losses, it is necessary
to reduce the dose accordingly. For example, if 15% of the
canopy was lost due to storm damage, reduce the dose by 15%.
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Example #1
A 25" DBH elm with approximately 30% missing
crown from pruning and storm damage:
| Step 1 - Label rate = 12 oz
per 5" DBH |
| |
= 25"/5" x 12oz =
60oz |
| Step 2 - Estimate of missing
crown |
| |
= Subtract 30% |
Total dose = 60oz – 30% (18oz) =
42oz Arbotect
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Example #2
A 17" DBH elm with a full crown
| Step 1 - Label rate = 12oz per
5" DBH |
| |
= 17"/5" x 12oz =
41oz
Subtract 3% per inch under 20" = sub
~ 9% |
| Step 2 - Estimate of missing
crown |
| |
= Minus ~ 0% |
Total dose = 41 oz - 9% (4 oz) = 37oz
|
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3. Large trees (above
28" DBH) require a higher dose to achieve the best results.
Increasing the dose above the label rate, however, is not
legal and we do not recommend you break the law. Rainbow Treecare
is conducting research to determine optimal doses for larger
trees and will use these results to make appropriate label
changes. The procedure we will test for large trees, consists
of making reductions to the canopy, as described above, and
increasing the dose by 3% for every inch of diameter above
28" DBH.
Symptoms of Overdose
Overdoses tend to occur on smaller trees, and the effects
are temporary for the tree. When overdosed, leaves tend to
turn a gray brown color and may curl or remain flat. Affected
leaves may drop from the tree. Symptoms tend to develop in
the lower canopy, and often on suckers of elm trees. Damaged
trees will refoliate later in the season or bounce back the
following spring.
Slippery Elms (Ulmus rubra)
Reduce the dose to one-half of the label rate. A full dose
may give phytotoxicity.
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