First of all what is a tree? A tree can be defined as a large, perennial, woody plant. Though there is no set definition regarding minimum size, the term generally applies to plants at least 6 m (20 ft) high at maturity and, more importantly, having secondary branches supported on a single main stem or trunk (see shrub for comparison). Compared with most other plant forms, trees are long-lived. A few species of trees grow to 100 m tall, and some can live for several millennia.
Lots of studies have been done so we can recognize may stresses that can occur in trees. We can diagnose the problem, by determining whether stress is biotic or abiotic.
BIOTIC
Biotic stress involves; insects, mites, disease, animals, etc. Ways to diagnose are:
- Insects are visible
- Saw dust or frass on the ground
- Egg cases, webbing, beces, curled leaves, and honeydew
- Examine wood for brownish colour
- Girdling roots
- Examine twigs for sunken areas, blister like structures, fugal and fruiting bodies
- Foliar disease, discoloured spots and blotches, discoloured viens, galls
ABIOTIC
These types of stress are harder to recognize and correct than biotic. Abiotic stress is non-living factors such as soil, weather or the overall growing conditions.
When assessing abiotic, examination of more than the damaged parts is nessassary. Make sure to check surrounding vicinity and other plants to see if they are showing the same symptoms. Is the stress affecting the tree all of a sudden or has it been this way for awhile? Assess the soil, local weather conditions, any recent conditions; construction, pesticide and grading.
There are four factors to be examined when assessing what is affecting tree growth.
1) soil
2) hardiness
3) environmental stresses
4) human activites
Soil: Quality, Organic Material, pH, nutritional status, porosity and aeration.
Drainage: Soil drainage affects oxygen to roots and nutrient uptake. Drainage affected by many factors including texture of clay, silt or sand, mineral composition, OM and local water table.
Hardiness: The ability to withstand cold temperatures.
Environmental Stresses:
- Weather conditions or other natural factors
- Winter injury
- Lightning injury
- Wind damage
- Hail
- Ice and wet snow
- Competition from other plants
- Drought
Human Activites:
- Construction
- Improper maintenance
- Girdling stresses
- Site alterations
- Salt damage
- Pesticide damage
There are a lot of different stresses that can affect the way trees grow and live. Are you paying attention? Do you understand what to look for?
