Growth Regulators and Control
The tree growth regulator niche started only a couple of decades ago. They were utilized by large utility companies to keep trees out of power lines, but largely ignored by tree health professionals. Today, growth regulators are better understood, widely used and benefiting trees in ways beyond growth regulation alone.
There are many situations in the urban environment where slowing or reducing the growth of trees can be beneficial to the trees and to the properties they grow on.Plants Near Infrastructure
The conflict between the ‘grey’ and the ‘green’ infrastructures in urban ecosystems is well documented, often causing damage to both parties. There are many different scenarios where a growth regulator can help extend the useful lifespan and help meet the needs of the property owner.Mature Size Maintenance
When a tree is young, our practices often focus on promoting healthy, vigorous growth. As that tree matures, there may come a time where reducing and maintaining a consistent size is more desirable. Growth regulation can help keep them fitting in their locations for longer.
We use the growth regulator Cambistat®. Cambistat is applied to soil and may be applied anytime that this ground is not frozen or saturated with water.Emerald Ash Borer
The Emerald Ash Borer (EAB) has killed millions of ash trees since its discovery in southeastern Michigan in 2002. Native to Asia, this insect was probably introduced to the United States in wood packing material carried in on cargo ships or airplanes. Through a combination of natural spread and human activity it is now found in numerous states, including Minnesota and specifically, Rochester and surrounding areas. All of these locations place millions of additional ash trees at risk. It will continue to spread.
Trees at Risk: All native ash trees, including green, white, black, blue, and pumpkin ash.Signs of Damage
Symptoms of an early infestation may be difficult to diagnose. Be on the lookout for multiple declining ash in a given area and D-shaped exit holes that are approximately 1/8 “ in diameter. As an infestation progresses, small vertical splits in the bark can be seen on twigs or the main trunk and woodpecker holes may be present on trees. Trees may die after 2-4 years or less.Physical Appearance
Typically the top 1/3 of crown shows dieback and thins. Trees appear to lose about 30%-50% of their canopy after 2 years of infestation.
As the tree declines, epicormic shoots form at the interface between healthy and dead tissue anywhere in the canopy.
Distinct “S” shaped, frass-filled larval galleries that can range from 4- 20“ in length etch the xylem and phloem.
Adults are slender and can be 1/4” to 1/2” in length, they are dark metallic emerald green.
Larvae range in size from 1 -1 1/4” in length with pincer-like appendages on the last segmentHow Does Emerald Ash Borer Kill a Tree?
As the larvae develop inside the tree, they consume the vascular tissue of the tree. During this process, they weave back and forth creating “S” shaped galleries in the vascular tissue. These “S” shaped galleries essentially suffocate the tree, cutting off vital fluids to the canopy. This activity occurs behind the bark and can go unseen for years before signs or symptoms appear on the tree. Oftentimes, when symptoms begin to appear on the tree, the tree has already been infested for multiple years. Additionally, it is rare to see an adult borer which makes identifying infested ash trees even more difficult.
Prevention with insecticide products is critical when it comes to protecting ash trees.