What is stress? Stress Condition in which a tree is not in good health Factors promoting plant health are out of balance Light, Air, Water, Nutrients, etc.
Types of stress Acute stress Disorder that occurs suddenly or over a short period of time Examples: pesticide sprays, frosts or freezes, mechanical injury, etc. Chronic stress Disorder occurring over a long period of time Nutritional imbalance, improper soil pH, long term weather changes, incorrect light intensity, etc.
Types of stress Biotic stress Disorder that occurs from a living organism Examples: insect feeding, disease infestation, animal damage Abiotic stress Disorder occurring from a non-living source Examples: Nutritional imbalance, frost damage, flooding, etc.
Types of stress Primary (inciting) stress Usually a chronic factor effecting the plant’s overall health Examples: nutrient imbalance, improper soil pH, construction damage, weather, etc. Secondary stress Usually a biotic factor that compounds the stress Disease or insect pest
Soil and site problems Physiological disorders Physical and mechanical injuries Insects and other pests Diseases General Examples of Stress
Soil and Site Problems Root related problems difficult to diagnose WHY? Symptoms typically appear on trunk and canopy Typically abiotic, chronic, primary stress Compacted soil Salt usage Soil pH Soil water holding capacity Grade changes and soil layering
Soil and Site Problems Soil compaction is extremely difficult, expensive, and often impractical to correct once it has occurred Avoid grade changes and soil compaction in the Critical Root Zone (CRZ) or Radius (CRZ) DBH x 1.5 = __ft of radius
Physical and Mechanical Injury Fire injury Use appropriate controlled-burn strategies Animal feeding Use tree wrap and fencing to protect May be associated with other stress ie. Woodpeckers & borers Lightning Install lightning protection in trees on special trees Vandalism (and stupid stuff) Lawn mower damage Mulch trees and educate the person with the weed-whip!
Architectural Problems Improper pruning Double leaders Included bark
Family A’s Tree - Not Pruned When Young Family B’s Tree - Pruned When Young At Planting 3-4 Yrs. 5-7 Yrs. 15 Years later
Insects Many insects, harmful or not, may live on plant Different life stages may be harmful to plant Most insect damage is result of feeding activity Biotic and typically secondary stress Leaf feeding insects vs Wood boring insects
Courtesy of D. Herms, OSU/ OARDC Scars the xylem tissue on the surface of the sapwood Feeds on phloem tissue just under the bark
Insects Develop IPM strategy for insect control Resistant varieties i.e. don’t plant ash trees? Scouting and monitoring Preventative measures Systemic insecticide, inspect incoming stock, etc. Curative measures
Diseases Susceptible host, pathogen, and favorable environment must be present for infection to form Most pathogens are host specific Part of tree affected indicates severity of disease Leaves, stems, trunks, roots, flowers Cosmetic vs. fatal Biotic, chronic or acute, typically secondary
Tree Selection For a healthy urban forest… No more than 10% of any single tree species. No more than 20% of any tree genus. No more than 30% of any tree family. (Frank Santamour, Jr. 1990. METRIA 7)
City of Janesville, 2009 http://www.jstac.org/Inventory.html