Keeping your trees healthy

By Pam Wallace

U. C. Master Gardeners

We all should know by now the value and benefits of trees in our landscapes.

• Trees improve air quality through photosynthesis and the storage of carbon.

• Trees provide shade in our landscapes, which reduces the water needs of surrounding plants, and help keep your home cooler, which reduces electricity usage.

• Trees reduce soil erosion by slowing storm water runoff.

• Trees provide us with food and animals with food and shelter.

• Trees improve property values.

As our climate changes and we are faced with watering restrictions, we need to take steps to protect our trees and help them survive the drought.

According to a recent study published in Geophysical Research Letters, a journal of the American Geophysical Union, it will take several years to recover from California’s four-year drought. Specifically, researchers studied the Sierra Nevada and found that the lackluster snowpack there, year after year, created a sizable water deficit that the state may not recoup until 2019. With California facing one of the most severe droughts on record, in 2015 Governor Brown declared a drought State of Emergency and required public water systems to reduce water usage by 25% statewide.

The Visalia City Council revised the “Water Emergency” water conservation ordinance, effective June 16, 2015. Approximately two thirds of water used in Visalia is for landscape irrigation. Here is the updated watering schedule for Visalia residents:

March – November

Even Addresses – Wednesday and Sunday;

Odd Addresses – Tuesday and Saturday

All watering is to be done before 10 a.m. and after 8 p.m. to reduce evaporation loss.

December – February

No watering allowed

As we reduce the number of days per week to water, we may not realize the impact this will have on our landscape trees. Trees in irrigated landscapes become dependent on regular watering, especially trees in lawns. When this water is reduced, trees can suffer and eventually die.

Here are some tips to reduce the effect of the new watering restrictions on your landscape trees.

• Deeply and slowly water mature trees one to two times per month with a simple soaker hose or drip system toward the edge of the tree canopy — not at the base of the tree. This enables trees to grow deep roots that help them withstand drought and longer periods between irrigations. A slow irrigation allows the water to percolate deeper into the soil. Arborists recommend applying water to a depth of three feet. Use a hose faucet timer to prevent overwatering.

• Young trees need 5 gallons of water two to four times per week. Create a watering basin with a berm of dirt. This basin should be constructed a little higher around the trunk of the tree, so the water drains away from the trunk.

• Do not over-prune trees during drought. This can stress your trees, or stimulate a flush of new growth, causing them to use more water.

• Mulch, Mulch, Mulch! 4 to 6 inches of organic mulch keeps tree roots moist and cool, helps retain moisture in the soil, and releases nutrients to the tree. Be sure to keep the mulch at least 3 to 12 inches from the base of the trunks to prevent rot.

Put a 3- or 5-gallon bucket on your shower floor to catch the water while you are waiting for the water to get hot. Use this water for your trees, making sure it is free of non-biodegradable soaps and shampoos. You’ll be surprised how easy this is to do and how much water you can save from going down the drain!

Tree loss is a very costly problem; not only in expensive tree removal, but also in the loss of the benefits a tree provides. By following these tips, you will better equip your landscape trees to survive their reduced watering this summer.

– To contact the Tulare/Kings Master Gardener Program, call 559-684-3325, e-mail [email protected] or write to 4437 S. Laspina St., Suite B, Tulare, CA 93247.

– This column is not a news article but the opinion of the writer and does not reflect the views of The Foothills Sun-Gazette newspaper.

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