Try these tips if trees are in decline

Russ Thompson and the Southern Nevada Arborist Group are noticing trees in decline all across town. He took me on a tour of some subdivisions and tree decline was everywhere.

Thompson defines tree decline as a gradual deterioration in tree health. It is a common problem everywhere. Symptoms include stunted growth, premature leaf drop, late spring leaf development, sparse foliage, light green or yellow foliage, twig and branch dieback or other abnormal symptoms.

When stress occurs, trees survive temporarily by using stored food reserves, but once that's used up, decline appears. It may take three or four years for decline symptoms to appear.

There is no single reason for tree decline. It's usually a combination of stresses leading to reduced vigor. Some common causes are underwatering or overwatering; underfertilizing or overfertilizing; chemical injury; drought; improper planting; compacted soils; girdling roots; poor maintenance; sunburn; high soil pH; bad pruning; and poor growing conditions.

In Thompson's opinion, tree decline primarily evolves from a lack of water, especially with trees that cannot withstand extended periods of drought.

Water restrictions for four minutes, three times a day may lead up to the problem. Water is not getting to the tree roots. On the back of Southern Nevada Water Authority's watering guide, it advises you to water trees and shrubs longer because of their deeper roots.

If you have a lawn under your tree, Thompson suggests placing the garden hose at the tree's dripline and let it run slowly for 20 minutes and then moving it to another location to deep-water your trees. This pushes salts away from the roots to enhance your tree's health.

Thompson said prevention is the key to controlling tree decline. Once decline symptoms begin, it is difficult to reverse. However, it's possible to slow decline if caught early with proper care and management.

In some cases, Thompson said, the decline can be linked to the Water Smart rebate program, which removes sod from landscapes. Thompson has come up with a cookbook approach to removing sod while protecting a tree's health afterward:

• Do not let heavy equipment under trees; they compact the soil.

• Spray the grass you plan to remove with a herbicide; it may take more than one application to eradicate.

• Remove unsuitable trees if they are a problem.

• Continue to water and fertilize trees through the conversion process.

• Scalp the lawn down to bare soil. Do not use a sod cutter or grub hoe to remove sod, advised Thompson. Leaving the topsoil protects the embedded tree roots, which waters the tree.

• Place emitters over the area out to the dripline so you provide water to the entire area under the tree's canopy.

• Plant your new, colorful, drought-tolerant plants.

• Cover the surface with your desired mulch to a depth of two to four inches.

BECOME A DESERT GARDENER

Take part in the fall gardening series at the University of Nevada Cooperative Extension's Lifelong Learning Center at 8050 Paradise Road. All classes begin at 7 p.m. for the next four weeks: On Wednesday, Helen Brown will tell the advantages of fall vegetables; on Oct. 14, Diane Eisen will take the aches out of those gardening with physical limitations; on Oct. 21, Scot Troter will share tips of knowing when to water; and on Oct. 28, Jeneane Young will show you how to grow anything in the desert. Classes are free, but call 257-5555 for reservations.

EDIBLE LANDSCAPES

As energy costs rise, so do food costs, but you may not need to go farther than your own backyard to get a healthy snack or nutritious meal. Learn from those who have created their own food supply in their yards at 8:30 a.m. Saturday at the Springs Preserve, 333 S. Valley View Blvd. Call 822-7786 for reservations.

NATIVE PLANTS BEHIND THE SCENES

This Saturday's tour beginning at 10:30 a.m. takes you on a walk through the Springs Preserve trails, introducing you to plants native to the site. Learn to identify them and of their historical uses. Please wear sturdy shoes. It's free, but reserve your spot by calling 822-7786.

IRIS FALL WORKSHOP

Do you want new irises in your garden? Do you know how to divide and plant them to raise blue ribbon flowers? Then come to the Las Vegas Iris Society workshop at Plant World Nursery, 5301 W. Charleston Blvd., from 10 a.m. to 2 p.m. Saturday to get help with your iris questions. For details, call 228-0827.

Linn Mills writes a garden column each Sunday. You can reach him at linn.mills@springspreserve.org or call him at 822-7754.