Jumping Oak Gall

Asked June 21, 2014, 9:13 PM EDT

Will this effect or destroy the trees? Is there something to prevent this or treat it?

Wayne County Michigan

3 Responses

In general you need not try to control any type of gall on oaks. Jumping Oak Gall can cause severe defoliation with a heavy infestation, and may warrant treatment if the tree’s health is being affected. A healthy tree will grow another set of leaves within a few weeks of being defoliated. Keep the tree watered during long droughts.

According to Univ. of Minnesota Extension - “Galls are growing plant parts and require nutrients just like other plant parts. Its possible that galls steal vital plant food and adversely affect plant growth. This is most likely a problem when galls are numerous on very young plants. Injury may also occur if galls are numerous on branches or if abundant for several consecutive years. In most cases, however, galls are not abundant enough to harm the plant.”

If you think your tree is being stressed too much, and the tree is large, you will need to consult a certified arborist to confirm the identity of the pest, and to schedule treatment at the proper time. Control treatments are typically applied in early spring. Timing is critical to control. Large trees require professional equipment and/or chemicals. However, Jumping Oak gall has not been completely researched and control options are not yet proven. Here is an article discussing that—

If your tree is small, say under 12 ft, you can try to protect it with a tree and shrub systemic insecticide that is mixed and poured in the root zone area. You would do this next spring before the leaves are out. Always read and follow the label of the product you choose. (Bayer Advanced Tree and Shrub is one brand, there are others. I use this as an example, not an endorsement.) But, if your tree is not severely affected, then no treatment is necessary.

Here is a link to a short article about Jumping Oak Gall- http://msue.anr.msu.edu/news/jumping_oak_gall_causing_damage_to_white_oak

If you decide to consult an arborist, you can find one by using the ISA web site- www.treesaregood.com and clicking on the “Why Hire an Arborist” topic, then the “Find an Arborist” topic ½ way down the page.

Please write back if you have any questions. Thank you for using our service.

Is this common in western wayne county? I have never seen this before in our area. Most articles mention California.

The following information from Ohio State University Extension indicates the galls have been widespread since about 1870---

“Jumping oak galls have been long attributed to one gall-wasp (family Cynipidae), Neuroterus saltatorius. However, there is now some debate as to whether or not jumping oak galls are produced by a single gall-wasp species or by several species of gall-wasps. The question centers on the occurrence of jumping oak galls on a wide range of oak hosts; from chinkapin oak (Quercus muehlenbergii) in Ohio to valley oak (a.k.a. California white oak, Q. lobata) in California. Such a wide host range over a large geographical area is very unusual for gall-making insects; gall-makers are normally highly specific to their plant host. Thus far, entomologist appear to agree that jumping oak galls are produced by wasps in a single genus, so some reports refer to the gall-maker as, Neuroterus spp.

Reports in the literature regarding Neuroterus saltatorius describe the wasp as a non-native invasive species and the galls have been reported as far back as the 1870's in the eastern U.S. Serious outbreaks with significant leaf damage have been reported in past years in the forests of Wisconsin, Indiana, Kentucky, and Ohio.”

The two links I gave you are from Michigan and Ohio. Jumping Oak Gall is common here. The uncertain factor seems to be which exact insects can cause the galls.
You may see a lot of references from California because of their large commercial production of plant materials; so they publish material of interest to commercial growers.
Remember that insects, animals and plants can all have ‘banner years’ of activity as well as ‘low years’ of activity. This year’s weather and the timing of the wasp’s hatching may have been just right in your area to cause a noticeable infestation. If you are not sure you have this particular gall, you can send a sample to the MSU Diagnostic Lab to confirm its ID. See www.pestid.msu.edu