A lot of time has passed and many younger Arborists would not be aware of the work by Manion (1991) in Tree Disease Concepts. I want to share the Disease Decline Spiral. A fantastic model for tree decline and explanation that it is rarely just one thing that causes tree decline.
Manion described 3 sets of factors: ✅️ PREDISPOSING FACTORS ✅️ INCITING FACTORS ✅️ CONTRIBUTING FACTORS
The first were long-term slowly changing factors such as soil, site, and climate. These predisposing factors alter the trees' ability to withstand or respond to injury-inducing agents.
The second group of factors were called inciting factors. Their action is short in duration. They may be physiological or biological in nature. These generally produce dieback of small branches. Examples of incitants are insect defoliators, late spring frost, drought, and salt spray
A third group of factors, called contributing, were suggested to include a collection of environmental factors as well as biotic agents such as canker and decay fungi and bark and wood boring insects.
These were demonstrated in a spiral showing continued decline until the tree dies. When assessing trees that's are stressed or declining, ask yourself...
What are the primary, secondary, tertiary or possibly quaternary issues and symptoms?
Often the most obvious symptom is not the primary, but a sign of other problems.
some of the best arboriculture was done decades ago.
Manion described 3 sets of factors:
✅️ PREDISPOSING FACTORS
✅️ INCITING FACTORS
✅️ CONTRIBUTING FACTORS
The first were long-term slowly changing factors such as soil, site, and climate. These predisposing factors alter the trees' ability to withstand or respond to injury-inducing agents.
The second group of factors were called inciting factors. Their action is short in duration. They may be physiological or biological in nature. These generally produce dieback of small branches. Examples of incitants are insect defoliators, late spring frost, drought, and salt spray
A third group of factors, called contributing, were suggested to include a collection of environmental factors as well as biotic agents such as canker and decay fungi and bark and wood boring insects.
These were demonstrated in a spiral showing continued decline until the tree dies. When assessing trees that's are stressed or declining, ask yourself...
What are the primary, secondary, tertiary or possibly quaternary issues and symptoms?
Often the most obvious symptom is not the primary, but a sign of other problems.
some of the best arboriculture was done decades ago.