Saving water helps desert plants

Angela O'Callaghan

Thursday, Sept. 4, 2008 | midnight

Occasionally, I am asked why we need to worry about conserving water in Southern Nevada, in the Mojave Desert. The question comes as a response to our efficient water recycling system. According to this peculiar logic, we have a very competent method for recapturing the water we use, and the bulk of our water actually comes from the Colorado River, anyway. What difference does it make whether we care for our water quantity?

It makes a huge difference.

We cannot be complacent because we have a thriving water-recycling program. When we use water wastefully, it is not recycled, not cleaned up and not put back in our supply. If you have looked at Lake Mead over the past few years, you have probably noticed a big white ring around its border. Less water getting back in there means less water in there, which means more concentrated pollution problems and more work for the equipment we depend on for our drinking, cooking, bathing and landscape water.

Recycling only happens when the water gets back into the system. If it pours out into the street, it is wasted. When it evaporates, it goes into the atmosphere. That raises our humidity. Remember when you first moved to the desert and said, "Yes, the temperature is 115 degrees, but it's a dry heat." Wasting water means the relative humidity here can go from 5 or 10 percent (normal for the Mojave) to 25 or 30 percent. When we let water drain from lawn sprinklers, or when we wash the car in the driveway, using a hose; when we can watch the water flow down into the gutter, we are not replenishing our water stocks. We drain them, and create more environmental problems.

As a horticulturist, a biologist, I have spent much time studying plant diseases. Part of my job is to help when plants start showing distress. I have looked at many stressed plants here, but few diseased ones. Plants have problems caused by insects or bad drainage, and many suffer because they are not adapted to a land of intense winds, high temperatures and scalding sun. With certain exceptions, like powdery mildew on roses and sooty canker on a few trees, most of the common disease organisms do not survive this dry climate. The bulk of problematic fungi and bacteria need humidity.

When the humidity increases, the atmosphere becomes more hospitable to the fungi and bacteria that cause problems to our landscape and garden plants. When we are heavy handed with misting, or sprinklers are not situated properly, then we create new homes for unfamiliar and unwelcome guests.

As long as it stays dry, we need not worry about most blights that affect our favorite garden vegetables and ornamentals. We can keep plant diseases near the levels they should be. There are many ways to do that, including using desert-adapted plants, but one important way is by being a careful water manager.

Keep the Desert Dry.

Angela O’Callaghan is the area specialist in social horticulture for the University of Nevada Cooperative Extension. She can be reached c/o the Home News, 2360 Corporate Circle, Third Floor, Henderson, NV 89074, or [email protected].