Oak Wilt Diagnosis on Monterrey Oak in Kerr County
I received a call about a Monterrey Oak (Quercus Alba or Mexican White Oak) that didn’t look very good. This is a residential property near Kerrville State Park in the 2800 blk of TX 173, near Comanche Trace. It is close to the river and most of his Oaks that are left are dying from Oak Wilt. The red oaks are dying off annually, the live oaks are infected but surviving and now the MX Oak is looking sick. This oak tree was given to my client 15 years ago with the KPUB free tree program. (which I LOVED) He planted next to his house in the backyard, next to infected oak wilt trees. There was also a young red oak that was obviously infected with OW about 25’ away. As I inspected this white oak, I knew this was oak wilt, yet I didn’t see the “classic” symptoms that I had been taught all these years. This oak had a very thin canopy, yellowing of leaves with some marginal tip burn and a very light necrosis of leaf. I took several samples from oaks on this site. They all came back POSITIVE with OW Bretziella fagacearum from TX Agrilife Plant Diagnostic Lab. The oaks cultured out in 12 days. The red oak trees that were infected have been removed. This white oak and the live oaks will all stay for further observation. So, if you’re expecting the classic signs -don’t. Look for a pattern of mortality in the area. I am not for sure if this tree grafted onto the oak wilt center, since I can’t see underground, but that would be my hypothesis.
We all had such high hopes for this tree being resistant to OW. Unfortunately, I am seeing more and more OW where I was told wouldn’t happen much. In 2018 RTS diagnosed OW on Post Oak in Medina county, Lacey Oak in Upper Turtle Creek area and now on the Monterrey Oak in Kerr County.
Now what do you plant? I would say Cedar Elm or Mexican Sycamore. Anything native that is size appropriate for your yard and space. If you are in OW areas or have hot spots of OW near you, plant a diverse group of trees. I will have a list on my website with all my favorite trees.
If you have any questions, or would like a site consultation…Oakwilt.com or 830-955-0304
Karen Rockoff is-
International Society of Arboriculture Certified Arborist TX3308A
TX Oak Wilt Qualified
TX Master Certified Landscape Professional 4803
TX Forest Service Wildfire Mitigation Specialist
TDA Licensed Applicator