I’ve lost five 4-year-old trees this year, and have another half-dozen that are badly damaged. Mostly apples, but I also lost a Shipova and have a Rabina Mountain Ash that seems unlikely to make it. Now that I’m aware of the issue, I feel like I have a chance. But despite having read everything I can find, I still don’t feel I have a surefire plan to prevent them from eventually killing the rest of my younger trees.
For those of you with severe apple borer problems, what have you found that works? My current plan involves painting the trunks with a mixture of Neem oil and Surround, and physically extracting the larva with a knife and wire every time I see a hole with frass. I’m open to harsher options, but I’m not finding any that are still available to homeowners.
In the meantime, here are some links that I’ve found useful:
A great 1919 report by Fred Brooks:
Fedco’s suggestions:
A 2020 thread here:
A Holistic Orchard Network thread summarizing Michael Phillips approach:
i guess i should be grateful ive never seen these borers here. im surrounded with mtn. ash, chokecherry and serviceberry. can’t say I’ve ever seen a beetle like that either.
What we do is paint the trees with a thick layer of lime wash (you can use cheap interior latex paint, too).
Keep the trunks exposed so you see the frass ASAP. Then it’s the knife and wire.
I am trialling some fragrant underplanting, but time will tell.
Btw. Rabina (Ryabina) means literally “European mountain ash”.
Painting the trunks white does seem very helpful for looking for evidence of “frass”. I haven’t quite figured out how to combine this with the Neem oil in a way that I can put it on in a single application. I tried mixing the Surround into the Neem oil, hoping it would leave it white, but it doesn’t have any opacity and looks more like peanut butter. You can see it’s been applied, but it doesn’t provide a useful white background. My current idea is to mix Titanium Dioxide powder with the straight Neem oil to turn it into an a white oil paint. I’ll put that on for the next application and report back.
I hadn’t realized it was a literal translation! Here in the US, “Rabina” usually only refers to a particular selection of European Mountain Ash that has (slightly) better tasting berries: Rabina Mt. Ash - One Green World.
I thought so. The fun part is that we have named sweet varieties and I’m sure the Russians and others have named their special strains as well.
I wonder, if someone sourced it locally and asked the million $ question “So, what do you call this tree?” in English…
I hadn’t realized some people consider it a carcinogen. It seems to be thought of very differently in North America vs Europe. In the US, it’s often considered the “safe choice” for sunscreen because it doesn’t have “dangerous” chemicals. Here’s an article about the US vs Europe: Titanium Dioxide, banned in Europe, is a common food additive in the U.S..
But I do appreciate the different perspective. Since I’d like to use a high concentration of Neem with a white background, and since I’ve already bought it, I think I’ll still try the Titanium Dioxide, but I will be especially careful to avoid inhalation while mixing it. And I’ll try to do a comparison with slaked lime.
So I went ahead and mixed up an trunk paint with the Neem oil and the Titanium Dioxide. I used a 1:1 ratio by volume, and wore a mask while measuring the dry powder. It mixed reasonably with just a spoon, and I thought it might be enough, but didn’t seem perfect. So I hit it with an immersion blender, which turned it into a perfectly smooth bright white paint.
It applied as well as one could hope. It adheres well to the trunk, the same as a thick commercial paint would. It gave me a bright white background to spot any future frass, and it leaves the trunk coated with a layer of Neem. Time will tell if it’s actually effective against borers, and I really hope it doesn’t somehow damage the trees, but I’m totally satisfied with the result and will use this approach again.
The only things I’d do differently next time is to plan my mixing and measuring a little more carefully. It’s a strong white oil paint, and hard to get off anything it touches. I made an applicator bottle by cutting a hole in the top of a plastic peanut butter jar so that I could tighty fit the handle of a paintbrush. This worked well for application and storage. Next time I’ll blend directly in this rather than blending in something else and trying to transfer. And I’ll do the blending outside rather than on the kitchen counter!
