Damage to trees from extended drought can happen over a period of years and includes stunted growth, canopy die-back, and possible death of a tree. Trees can take up to three years after a drought to show symptoms. A sign of extended drought is canopy dieback, which can be directly correlated to the loss of tiny absorption roots. During the hottest and driest months of the summer, the fine roots in the upper portion of the soil begin to die causing an imbalance between the amount of absorption roots and the above ground canopy. If and when rain does present itself, trees may not be able to take full advantage due to the fine root loss. The result is a decline of the canopy through branch die-back. If drought persists for multiple consecutive growing seasons trees may not be able to recover and can ultimately lead to death.
Pest problems are another side effect that can be associated with long-term drought. Wood boring insects, such as Ambrosia Beetles and Pine Bark beetles prefer weakened trees and actually seek out weakened trees. As trees become weakened from drought, these pests invade rapidly.
Some pests such as Crape Myrtle bark scale, Gloomy scale, spider mites and aphids tend to cause more damage to trees during long periods of hot and dry weather.
To reduce the effects of long term drought on trees:
- Install a 2-4″ layer of shredded hardwood mulch to conserve water, keep soil temperatures cool
- Install mulch from the trunk to the dripline keeping the mulch approx 6 inches from the base of the tree
- Water slowly to allow for absorption and prevent runoff
- Infrequent, deep watering promotes deeper roots and increases drought tolerance
- Install a drip irrigation system or use soaker hoses