Shella McBride and David Appel in their article on Hypoxylon Canker for AgriLife Extension state that once Hypoxylon Canker is evident, it is usually too late to save the tree. The Arborlogical Services web site says that it is extremely rare to see Hypoxylon Canker on the trunk of a tree and have the tree recover or survive. The Hypoxylon Canker article on the Texas Forest Service web site is even direr. It says that once the tree is actively infected, the tree will die. It also says that there is no known cure.
In the spring of 2011 during that record Texas drought, we removed two large branches from a large Red Oak (Quercus shumardii) on a client’s property in Grey Forest, TX. The client is a landscape architect and a winner of ISAT’s Best Development of the Year award many years ago. One of the two branches had Hypoxylon cankers on it and the other was dead, but had no cankers. One of the cankers on the live branch was closer than 12 inches from the main trunk and we were hoping to remove the branch before the disease reached the main trunk. During the next inspection of the tree we became aware that we had not been successful as a canker had developed just below the branch cut on the main trunk. We did a drench with corn meal water applied at the base of the tree. Our mix was one cup stone ground corn meal per gallon of water and we let it soak for several hours. We applied about 15 gallons of the corn meal water at the base of the tree.
The client took over with the treatments, applying a drench annually. A few years later we did an Oak Wilt injection on several Live Oaks on the property and we did a corn meal drench on the Red Oak at the same time. We also removed several large dead branches from the Red Oak that did not have any disease cankers present. The client’s opinion of this Red Oak in June 2019 from the point of view of a landscape architect is “the tree looks great.” That is survival and recovery.
Two years ago in 2017 we injected a large number of Live Oaks on a property in Boerne, TX for Oak Wilt. The clients were both dentists and were raising horses trained for barrel racing for their daughters’ racing team. Trees with no diagnostic Oak Wilt symptoms were flagged with blue, trees with symptoms were flagged with yellow, and two Live Oaks with Hypoxylon Canker were flagged with red and were not injected. The two oaks with Hypoxylon Canker did receive a corn meal water drench as did all of the trees that were injected with Alamo. All of the treated trees had also been drenched with corn meal water by the client several weeks before we did the injections and our corn meal water drench.
An inspection in 2018 revealed that 3 of the yellow flagged trees did not survive. All of the surviving trees were drenched in 2018 by the client and they plan on drenching again this year. All of the blue flagged trees have survived two years, the remaining yellow flagged trees have survived, and the two red flagged trees have survived. The two Hypoxylon Canker infected trees not only survived, they look better this year than they did when they were first treated in 2017 (in my opinion). That’s survival. The jury is still out on recovery.
Systemically Induced Resistance (SIR) or Induced Resistance (IR) using Trichoderma obtained from soaking whole ground or stone ground corn meal in water is showing promise for treating tree diseases. This is not peer reviewed research. It is just me playing with an idea based in science on a problem that is considered lethal with no treatment, no cure. It is anecdotal, but it is working. I’m 3 for 3. Actually, I’m 4 for 4. We treated another Red Oak with corn meal water at the South West School of Art that survived a year plus. It looked great when it was removed for a building expansion. I will probably soon make Dr. Linda Chalker-Scott’s list of Myths in Arboriculture.
Hopefully others will start playing with SIR or IR so we can see if I’m just lucky or we have something here that will help us with our care of trees. Trichoderma is not our only SIR weapon, but it is easy to use, very low risk, and inexpensive. Finding a tree infected with Hypoxylon Canker that you do not need to remove is rare. Give it a try when you find that rare tree that is worth the effort. Try it on some of the other diseases you encounter that are difficult to manage and see if it helps. Trichoderma is reported to be effective against Phytophthora and Armillaria.
David M. Vaughan
Certified Arborist TX 0118
ArborVaughan Consult, LLC