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. Proper 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.
Experience in treating trees over the past 30 years has shown that proper dosing is an art as well as a science, and it is a key to predictable results.
Determining Dosage
Determining Tree Diameter at Breast Height (DBH)
By convention, DBH is always expressed in inches:
Measure the DBH of the tree at 4 feet 6 inches (1.372m) above the soil line with a diameter tape (D-tape). If using a standard measuring tape, divide the measurement by 3.14 to get diameter.
Single Stem – measure the standard DBH of the tree.
Multiple Stem Split Below DBH – measure the DBH of the tree at the narrowest point between the root flare and split.
Application Rate
Apply 360 mL of Arbotect for each 13 cm of DBH
Dilute each 360 mL of Arbotect 20-S with 24 L of water.
Special Considerations
Do not use this treatment if trees are less than 25 cm DBH.
Use half rate of (180 cm per 13 cm DBH) for all non-Ulmus americana elm species to minimize the possibility of a phytotoxic response.
Reduce the dosage rate for trees smaller than 51 cm DBH that are missing or sharing canopies. Reduce the dosage rate by the % of canopy missing. For example if 20% of the canopy is missing, reduce the dosage rate by 20%.
