Mesquite Trees are Water Opportunists

Q. Do you have any ideas how to stop the flowers produced by mesquite trees? For the past two years mine seems to have gone crazy producing the little yellow flowers that create a constant scum of yellow on my pool all summer long. This mesquite has 1½ long spines on new growth together with the leaves.

Native mesquite in the Mojave Desert just outside of Las Vegas, Nevada. Restrained growth and flowering because of the 4 inches of rainfall the Mojave Desert gets each year.

A. The tree sounds like a native mesquite, perhaps the Honey Mesquite. This tree is native to our desert Southwest, a North American native plant.

            Production of fruit by olives and pods in mesquite, can be controlled by spraying the tree when flowers are open. The flowers must be present and open for the spray to cause the fruit to abort. So, timing of the spray is critical for success. Chemicals like Florel and Olive Stop are used. But sprays to prevent flowering are more difficult to find and apply.

            Under desert conditions of limited rain, flowers are produced only in the spring when temperatures warm up. If the soil has water in it, there will be lots of flowers. If the soil is dry, flowering is sparse. If this tree is watered freely then it is possible it can produce flowers, in waves, all summer long, with each flush of growth.

Mesquite make a good looking landscape tree if pruned and managed correctly. The density of shade has much to do with how much irrigation water it gets in the desert. Infrequent watering would produce filtered shade. Frequent watering produces dense shade. They would grow too fast if grown in wet climates.

            Desert plants, like this mesquite, are opportunists; they take advantage of water when it is present and restrict growth and flowering when water is not available. In other words, growth of all kinds including flowering is tied directly to irrigation.

Mesquite trees do not belong in lawns and they should not have flowers growing beneath them. They are prefect for desert environments.

            Manage its growth and flowering by managing its supply of water. Water less often but with lots of water when you do water. Give it water in the spring to so it can grow and flower and then restrict water the rest of its growing season.

            This restriction of water will curtail its growth and flowering to once a year. At least then the yellow scum needs to be cleaned out of your pool for only three or four weeks each year.