Creosote Bush and Spider Mites

Q. About a year ago you helped us diagnose a spider mite problem on our creosote bush. We took care of that as you directed. The results were encouraging and seemed to get the problem under control. However, we think the mites have come back with a vengeance and considering a severe pruning to revive it.

Creosotebush cut down probably with a grader in the front and unpruned creosote bushes in the back.

A.  Creosotebush can be cut back to a few inches above the ground and it will grow back after a few occasional waterings. Look at the creosotebushes mowed off near desert roads probably by a road grader from the DOT. Because they were cut down and got some extra water from the road when it rained, they came back like gangbusters; dense and green.

Predator/Prey

            What concerns me more is why the spider mites got out of control in the first place. Creosotebush has its share of spider mites naturally, but they are frequently controlled by predators such as other insects and mites. However, in your case, the balance between “good guys” and “bad guys” got out of hand with the “bad guys” winning.

            The problem with spraying a pesticide is killing off the “good guys”, then the “bad guys” get out of control because few or no predators are left. So, we usually avoid spraying pesticides unless we don’t have any choice.

Cutting Back Creosote

            I like your idea of cutting it back and letting it regrow. But I think you also must do something different or the spider mites will just be back again.

Weed Control

            Control weeds in the area. Spider mites like to feed on many kinds of plants including weeds, and these can play host to a growing population of “bad guys”. Secondly, be careful of watering too often. Creosote bush should never be on an automatic irrigation system because it just doesn’t like to be watered that often. Water it no often than four times a year with three of those irrigations during the hot months.