MAKE YOUR SPRINKLER SYSTEM SMARTER.

Byline: JOSHUA SISKIN

As winter approaches, it would be comforting to know that your sprinklers will automatically shut off when it rains. There is nothing more maddening than watching sprinklers come on in the midst of a downpour.

Well, there are no more excuses for irrigating when it rains. Thanks to rain sensors, you can now relax, knowing that your sprinkler system will shut down even when it drizzles. Hunter Industries, for example, has two rain-sensor products, each with a list price of less than $30. The Rain-Clik sensor is the more sensitive of the two and will shut your sprinklers off with the first drops of precipitation or even in a heavy fog. The Mini-Clik sensor, by contrast, may be calibrated to shut your system down after a certain amount of rain -- say 1/4 inch -- has fallen.

Hunter Industries has three other sensors worthy of consideration. If you live in a windy area such as the high desert, the Wind-

Clik sensor would be useful in shutting off sprinklers when high wind velocity makes watering -- except where drip irrigation is in use -- a futile exercise.

The Freeze-Clik sensor is another useful device for the high desert since it disables a sprinkler system as the mercury approaches 32 degrees Fahrenheit. Clearly, the possibility of hazardous ice formation on sidewalks and driveways, as the result of irrigating in freezing weather, should be avoided.

Finally, the Flow-Clik sensor shuts an irrigation system off when a pipe or sprinkler breaks, minimizing water waste. Details on these sensors are available at www.hunter

industries.com. The sensors are distributed through the many Ewing Irrigation and Hydro-

Scape stores located throughout the Los Angeles area and surrounding valleys.

MOTHS ATTACK CITRUS: From Chatsworth to Burbank, I have been receiving reports of curled citrus leaves accompanied by squiggly trails in the foliage. The party responsible for this unsightly development is the larva of a moth. The larva, a tiny caterpillar known as a leaf miner, burrows its way inside the leaf, creating, in the words of correspondent Cynthia Marks, a ``road-like pattern.''

On mature trees, the disfiguration that results is primarily aesthetic and should not affect fruit production. On young trees, however, there is more of a concern, especially since leaf miners do damage exclusively to young, expanding leaves in new flushes of growth. Lemon, lime and grapefruit are most susceptible to the citrus leaf miner pest, although other citrus family members may also become hosts to it.

Since the pest attacks young foliage, the least invasive control method would entail application of horticultural oil on small, newly forming leaves on shoot terminals.

The moths will not be able to stabilize themselves on the oily leaves and so will be discouraged from laying eggs -- which would hatch into the damaging larvae -- on the slippery surface.

Q: About a year ago, I bought several poinsettia plants. Two survived, and I would like to plant them in my yard. I heard they can't take hot weather. Where should I plant them?

A: Poinsettias are native to tropical Mexico, and were brought to the U.S. in 1825 by Joel Poinsett, the first American ambassador to Mexico.

Since they are tropical, they not only need protection from direct Valley sun but from the cold as well. The most robust poinsettias I have encountered in the Valley -- one in Sherman Oaks and the other in Granada Hills -- were growing against east-facing walls. Their placement allowed them to avoid hot afternoon summer sun. At the same time, the reflected light and heat from the wall behind them provided a measure of insurance against winter cold.

TIP OF THE WEEK: When selecting poinsettias for indoor decoration, avoid plants in sleeves, or which are crowded together, since they lose leaves and quickly deteriorate when deprived of air circulating around them.

If you have to travel very far, they should be transported in a roomy shopping bag.

Give them six hours a day of good ambient light, but avoid direct sun exposure and, as is the case with most plants living indoors, water only when soil is dry.