Damage to bur oak leaves
Thank you for using the Help Desk.
Clearly, your Bur Oak is experiencing some stress. More than likely the leaf damage is due to a pest munching on the leaves. In order to give you an answer would you answer some questions?
Have you seen any pests on the leaf, twigs, or trunk of the tree? Examples would be caterpillar, beetles, even grasshoppers. Look especially at the underside of the leaf for an actual pest or activity such as tunneling. You may have to look with a flashlight after dark when the pest is most active. Photographs of pest or evidence of pest are helpful. How old is your Bur Oak? Is the damage confined to one area of the tree such as canopy, one side or other of canopy?
I'm fairly confident that we are dealing with a pest as the holes in the leaf indicate a chewing insect.
I hope this is useful. Please feel free to send as many photos as you can showing detail. This will help me - us to determine the exact cause.
Thank you for the fast response!
No pests on leafs, twigs, or trunk. Tree is 20+ years, but has grown very little over the years. By this time of year, leaves would be turning yellow and fall off, presumably the soil was too dry. Last spring, I put a burlap sack on the soil around the base (not around the rootball). Almost all leaves are still green and feel velvety, but a few are turning yellow (see photo), possibly soil is too wet?
The chewed on leaves are scattered throughout, not limited to a particular part of the tree. I did not notice this leaf damage in the past (possibly because the leaves were already starting to fall off by this time). There are grasshoppers around, but I don't think they do not make such small holes in the interior of the leaves. We've had flea beetles munching on tomato plants, with damage that looks somewhat similar, but I didn't see any flea beetles on the bur oak. See attached for 2 photos of the underside of two leaves that have a small speck, perhaps a tiny bug?
Oaks are host to many leaf-eating insects, some more voracious than others, including gypsy moth, tussock moth, fall webworm, forest tent caterpillar, yellownecked caterpillar, and various other caterpillars incuding wolly bears and also some beetles, such as, Japanese beetle. Without a sample of the actual insect we cannot determine what is chewing on the leaves.
Controls may be needed for young trees, depending on the time of year and the extent of the damage, but a mature, healthy tree can tolerate the loss of some foliage without the need for controls.
Continue watering to mitigate tree health. Mulching 2-3 inches around the base of the tree but not against the trunk of the tree will help cool the roots and conserve moisture.
You may want to consult a certified arborist.
If you have a sample of the insect, send pictures. If you have further questions please contact us.