Drip irrigation is 30 percent to 40 percent more efficient than sprinkler irrigation.

Well-designed and properly managed drip systems are a great way to conserve water and cut down on the problems associated with sprinkler irrigation such as runoff, water spots on windows, uneven water application because of wind and water loss because of evaporation.

However, we should look at some of the problems that result from the improper use of drip irrigation:

Amount of water

A frequent cause of death of trees and shrubs in home landscapes is overwatering. Plant roots need water and oxygen. Too much water in the soil excludes air and leads to root rot. Even efficient drip systems on well-drained sandy soils can lead to root rot when set to water excessively.

Systems should not be run continuously -- smaller amounts of water fairly frequently is better than having the system run for long periods of time. A controller can make a drip system easier to manage.

Don't run the system all day or all night, even if someone tells you that you can't overwater plants in the Tri-Cities. This is false! It's illogical to install a drip system that conserves water, then waste water by running it continuously. Adjust your watering schedule with changes in weather.

Placement of emitters

Water applied by a drip system doesn't do any good if it's not applied where the plant needs it. Emitters are placed fairly close to the base of young trees and shrubs because of the restricted size of the root ball. As the plant grows, the emitters must be moved or repositioned, and more need to be added. Failure to do this can significantly restrict root and plant growth. If emitters that were initially near the trunk aren't moved, excessive water at the tree base or "collar" can lead to collar rot.

Good design

The ideal is to start with a landscape plan and a well-designed irrigation system. In reality, many landscape designs are based on availability of plants or the whims of gardeners. The ideal from an irrigation standpoint is to place plants in zones according to their water needs.

Good management

Drip systems need to be managed and inspected periodically. This means checking the soil in the root zone of the plants. Is it moist, too dry or too wet? Is the entire root system receiving moisture? Are there areas where emitters should be added or removed? Are any emitters plugged and in need of cleaning?

Without checking the soil for moisture, often the first sign that there is a problem is when a plant starts to die because of drought stress or from root rot. By that time, plants have gone past the point of no return.

* Marianne C. Ophardt is a horticulturist for the Washington State University Extension Office in Benton County.