Oak Wilt Across the Street

[BillyB]

My neighbor across the street lost a beautiful grouping of oaks to oak wilt at the foot of his driveway. Most are gone now but there is still a large one standing that's been dead a few years. Opposite them, on my side of our paved little residential street, are a few of my own. There are no side walks and there are probably 30-40' between the drip lines, about the street width. My trees are fairly young, about a jr high school equivalent age and about 2/3 mature size and reasonably healthy, I think. So far, I've been lucky and have avoided infection but still, I'd appreciate it if you would help me with some questions:

• Is my neighbor's remaining tree still infectious?
• Seasonality aside, at what point does an infected tree cease to become a risk to other trees?
• How concerned should I be?
• Are there any precautions I should take other than keep my trees pruned, assuming its done at the correct time of year, so as to reduce unnecessary stress and the risk of breakage during beetle season?

Thanks in advance for your thoughts!

 

[PJM]

What types of oaks are you talking about? It matters in terms of susceptibility to the disease and how it is spread. The red oak group are more susceptible to the disease and are more likely to spread it to nearby red oaks through root grafting and beetles. Red oaks can still pose a risk of spread sometime beyond being dead, due to the spore mats that develop under the bark. The white oak group are less susceptible, capable of living with the disease for many years. They are also less likely to spread it, partly because they don't develop the spore mats that attract the beetles.

 

[BillyB]

What types of oaks are you talking about?

I'm talking about the red oak family, more specifically I believe mine are pin oaks. Sorry about not including that in my starting post. I had been aware that red oaks are more susceptible but did not know about the spore mats. Thanks for the additional info.

Is there any way to determine probability of ongoing infection?
Please see other questions in starting post.

Best regards!

 

[Jed1124]

I would have a aborist come out to get a price on preventative Alamo injections.

 

[PJM]

• Is my neighbor's remaining tree still infectious?

Most likely yes. As well, there is a probability that other nearby red oaks are likely to be or will soon become infected due to that tree remaining on site.

• Seasonality aside, at what point does an infected tree cease to become a risk to other trees?

When it is fully removed and all existing root grafts have been disrupted.

• How concerned should I be?

It sounds like you care for your tree, so I would be pretty concerned about OW spreading to your tree.

• Are there any precautions I should take other than keep my trees pruned, assuming its done at the correct time of year, so as to reduce unnecessary stress and the risk of breakage during beetle season?

Follow seasonal pruning recommendations, including the use of wound dressings if having to prune or repair branch damage during the peak adult beetle season. Consider fungicide treatments as suggested by Jed. Those are not a guarantee, and may only mask the symptoms of infection. Consult with a qualified arborist for an on-site evaluation of your tree.

 

[BillyB]

Thanks for the heads up! Before these replies I hadn't realized that the threat was onging. Now I do. First thing to do is to try to convince my neighbor to process the dead tree. Then follow recommendations above.

 

[BillyB]

Thinking more about this:

For the deceased tree across the street to pose a risk of infection, not only must the spores be present but there must also be a method for transmitting them. Would you agree? Given that transmission generally occurs via root connections or beetles, what is known about:

• The ability of oak trees to grow roots beneath roadways?
• Whether beetles feed on dead trees and what specifically they feed upon, sap, spore mats, or both and, if sap, whether it is reasonable to assume that it's dried up by now given that the tree has been dead for several years and no longer attracts beetles?

I ask these questions not because I like to live dangerously, only for a better understanding of the risk level.

 

[ATH]

Oak wilt will not remain viable contagious indefinitely after a tree has died. The fungus needs a live tree to remain viable...there will still be viable pores for a while, but not forever from a dead tree.

You said the tree has been dead for "a few years". Is that 3 years or 7 years? I think it is probably possible to spread an infection from a 3 year dead tree...but not a 7 year dead tree. There is no 'hard deadline', but even 3 years, the chances that your tree will become infected from that are dropping rapidly. The beetles that carry Oak Wilt are also no longer attracted to that tree, so not many will be visiting it to carry the fungus around like they would have as the tree was dying or right after death.

If your tree hasn't been infected by that one yet, I'd bet on low odds of it happening now. Not that your tree will never get infected...just not as likely from that tree.

Certainly worth having a qualified arborist evaluate your tree with you to come up with a long-term management plan. Your exact location and local experience (and budget/your willingness to invest in the tree) will be one of the biggest things influencing whether treatment makes sense.