Water is the single most limiting essential resource for tree survival and growth. Drought conditions can severely affect young and old trees alike leading to tree decline, pest problems, and non-recoverable damage as well as decreased rates of diameter and height growth.
More than eighty percent of the variation in tree growth is because of water supply.1 Although providing adequate water to newly planted trees is essential, replacing older, more valuable trees lost or damaged due to lack of water can be especially difficult since they can take decades to grow to the same size. With the many social, economic and environmental benefits that trees provide, it is important to continue caring for our trees even in times of drought and tightening water restrictions.
The signs of drought stress can be observed mostly in the foliage of trees. Symptoms such as leaf drop and curling, wilting, or discolored leaves as well as dead branches are all signs of dry roots. Many people may not realize that their mature trees are stressed since these symptoms first appear in the top center portion of the canopy which may be far from view.2 However, it is better to apply water preventatively before these symptoms even appear.
Considering that state and local watering restrictions may be in place, here are some tips to help weather the dry conditions:
Tips for Watering Trees During a Drought
- Mulch trees. (Add mulch at a depth of three inches. Place it over the tree roots. Do not place mulch against the tree trunk.)
- Use recycled water or gray water from your home (dehumidifier, air conditioning condensate, or shower before it heats.)
- Pump water from other sources such as detention ponds, lakes, creeks or cisterns. Remember to get permission from the landowners if the water source is not on your property.
- Use gator bags and refill them with recycled water.
- Ask the fire department to use water that is recycled from their trucks. Follow crews as the fire hydrants are drained and collect the water. A large tank is needed to collect water as it is under high pressure.
- Get a permit (contact your local county government) and pay to bring water in from other sources. Your trees provide more benefits than this cost.
- When you are able to provide water, the most beneficial time to irrigate plants is during the late night and early morning hours. Evaporation is minimized, and the foliage has time to dry out during daylight hours. Evening watering is efficient for water use, but should be applied after dew is on the leaf surfaces
- Install a rain barrel at your planting site.
What Not to Do During Drought Conditions:
- Do not prune live branches which forces the tree to expend energy to heal the wound from the cut. Removing live foliage also reduces the capacity of the tree to grow once rains return.
- Do not fertilize trees in extended drought since this pulls water from the roots and forces the tree to expend precious energy to process the fertilizer.
- Do not dig under the canopy of a tree during drought because this will reduce the capacity of the tree to uptake water.2
- 1 Coder, Kim D. 1999
- 2 Gilman, Edward F. 2007