Redbud Tree Issues

Home Grown  by Keith Reed
Note: This problem produced hundreds of calls and inquires to the Payne County Extension Office a few years ago when this insect began showing up in large numbers. It was a common problem for two or three years then they simply moved on, or at least disappeared. While this is not really a health problem for the vast majority of redbud trees, it is something to be aware of in case the numbers continue to increase again.

In most cases, the leaves become folded or rolled up and many eventually fall off the tree. The problem is caused by the redbud leaf folder. This insect (the adults are non-descript grey moths) lays its eggs on the leaves. The eggs hatch and the very small caterpillars begin feeding causing the leaf to fold or roll up. This provides protection for the insect from various predators such as birds. The damage is very unsightly as it often affects the newer leaves. The problem is often reported on smaller trees but all size trees can be affected.

The good news is this is primarily a cosmetic issue and should not cause long term harm to your tree.

If you happen to have an especially prized redbud or one that has been recently planted, you may want to control the insects. Begin by closely examining the affected leaves. If you pull the leaves apart and do not find any worms actively feeding, the life cycle has been completed and an insecticide application would be of no value. If they are still feeding, an application of an insecticide will provide some level of control, although this depends on the size of the insects and how well they have protected themselves inside the leaves. A Bt product such as Thuricide works very well against not only leaf folders, but other chewing caterpillars as well. Bt is a bacterial insecticide that works only on the digestive system of the caterpillar. The side benefit of this product is that it does not harm beneficial insects.

Just as with all pesticides, it is important to follow the label for proper application instructions. It should be noted that Bt works slowly. They will stop feeding shortly after ingesting the insecticide, but it takes a few days for the caterpillar to shrivel up and die.

It is also important to mention that butterflies have a caterpillar stage and would be killed by a Bt application. This is another great example of why you do not want to have the attitude of “spray everything just in case”. Knowing your enemy and treating for it only when appropriate is a fundamental key to Integrated Pest Management (IPM) principles.

For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at
keith.reed@okstate.edu, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

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