Irrigation systems need check before hot weather

By Rebecca Jepsen
for the Mercury News

With the weather heating up, May is the time to do a thorough inspection of your irrigation system.

If you use drip irrigation, emitters may have gotten clogged, animals may have chewed through the drip tubing or lines may have been broken by foot traffic through the garden.

Visually inspect your system. Flush lines by unscrewing the end caps and turning on the water. Check the flow from each emitter and replace broken or damaged emitters. Look for leaks or breaks in the drip lines and repair. You may need to reposition emitters to accommodate plant growth.

If you use an overhead sprinkler system, you should still do a visual inspection. If a sprinkler head isn't flowing or has low flow, use a screwdriver to unscrew it, clean the filter and check for cracks.

If you need to replace a part, take the old one to your local hardware store so you can be sure to get the correct part; they can look surprisingly similar when you are staring at the vast array of choices.

You may need to use your screwdriver to adjust the spray pattern to avoid watering your sidewalks, driveways or patio furniture.

Make sure pop-up sprinkler heads rise up enough to reach all plants; you may need to trim hedges or shrubs that are blocking the water spray.

To ensure that your lawn sprinklers are adjusted correctly and providing complete coverage, use the "can test." Set out similar-size cans across the lawn, turn on your sprinkler system and let it run for about 15 minutes. Check to make sure all of the cans have the same amount of water. If not, make adjustments or add heads as needed.

If you use an automatic timer, check the zones to make sure it is working properly. Also, take a look at the time setting. You may have forgotten to adjust for daylight-saving time, or it could be off because of a power outage.

Although we had a wet winter, the past two months [March and April, 2008] have been pretty dry. Now is a good time to thoroughly water trees and shrubs to encourage healthy roots and prepare them for the summer.

Trees planted in the lawn generally have enough water. For those planted in other areas of your landscape, use soaker hoses installed at the drip line of the tree. Make sure to keep the line at least 6 to 12 inches from the base of the trunk.

You may want to use a moisture meter or dig down at least six inches to check the moisture level of your soil; water when dry. Established native trees, especially oaks, do not appreciate summer water.

Q: I was wondering about the lasting effects of using dormant spray on our lemon and nectarine trees. There is a white residue left over from the spray. Is it toxic to dogs or to the fruit?

A: Dormant spray is not necessary, nor recommended, for citrus trees. It is not harmful to mammals, but may affect fish. It is best to let the spray dry completely before you or your pets come in contact with the fruit; be sure to wash the fruit before eating.