My beautiful black walnut tree is acting oddly this summer. For over 40 years it’s been growing, and dropping its nuts in the early fall. But this year it’s dropping them now, all tiny and under-developed! What’s going on? I see no sign of leaf die-off, the number of dead branches looks normal, I see no webs choking off anything! Any tree surgeons out there? I’m worried! What will my local squirrels and chipmunks do this winter?
If that’s what it is, you need to clean up the nuts to prevent the insects from establishing themselves in the soil.
I wrote a really long and detailed response to this but the damned board ate it. Here’s a slightly shorter version:
IANATS but I do have degrees in agriculture and horticulture. Here’s the things I’d look for.
Most people immediately think that anything wrong with a plant can be attributed to pests or diseases and reach for the pesticide. In fact. most plants die because of changes in environmental conditions, poor siting or poor planting. I’d look for these things first:
*What’s the weather been like? Are you in the middle of a drought? Has it been unusually wet? Abortion of fruit is a common reaction by stressed plants that need to conserve energy in tough times.
*Are there any open wounds on the plant that fungi or diease may have entered through?
*Has there been a chemical spill near the plant? Diesel is a particularly bad one because it hangs around in the soil for ages
*Has there been anything that has disturbed or compacted the root zone recently? Remember that the root zone for most trees extends twice the distance of the canoipy.
*Have you been doing any building works?
*Have any nearby trees or structures been introduced or removed?
*Any broken water pipes nearby that might have flooded the ground? Or have you recently fixed a broken pipe?
- How old is the tree?
*Anything else that has changed?
After looking at these things I’d try to eliminate any possible pathogens:
*Have a look at the walnuts, split them open. Is there any indication of disease, fungus or pest infestation?
*Have a look at the stems the walnuts hang off. Is there any indication of disease, fungus or pest infestation?
*Have a close look at the leaves of the tree. Is there any indication of disease, fungus or pest infestation? Any skeletonizing or curl?
*Have a good look over the entire plant. Is there any indication of disease, fungus or pest infestation? Particularly look for borers or termites. Also have a look at the bark - is it discoloured (usually lighter) underneath any old wounds or knotholes? (often indicates a fungal infection through the wound).
Without seeing your plant it’s a bit difficult to tell but those are the sort of things I’d look for.
I’m not really familiar with black walnuts so I can’t tell you any of their particular diseases but I’ll have a look in my reference books tonight.
thanks squink and motog. No unusual changes in the tree’s environment as is described above. Rain has been adequate, spring was cool, but now its hot and humid out as it often is. The tree is at least 50 years old, maybe older, and was planted by my grandfather.
I will inspect the plant’s bark, leaves and nuts as soon as conveniently possible.
Squink’s suggestion sounds like a good possibility. A full description and means of identification is here: http://www.na.fs.fed.us/spfo/pubs/howtos/ht_walnut/boring.htm
A general coverage of common black walnut problems is here:
http://www.na.fs.fed.us/spfo/pubs/howtos/ht_walnut/cover.htm
Take the tree to a doctor. A tree doctor. http://www.treedoc.com/
Yes, its probably not practical to take the tree out, however, you can take some leaf & nuts
to a local tree doc or store & they would let you know what’s up doc.
Apparently, walnut trees like a good thrashing every now and again, maybe that’s what yours needs.
Thanks again. I autopsied four fallen immature nuts, and found no signs of insects at all. The leaves look healthy, as does the rest of the tree. The nuts tended to have a brown streak thru the flesh outside the nutcore. Healthy nuts pulled from the trees didn’t seem to have the brown streak. Older nuts on the ground were brown thruout the flesh. I don’t know if this is normal decay, or a fungus or something. I couldn’t find anything like it described in the above links.
We’re in the middle of a severe drought here in VA and that was the first thing I thought of; however, you report that rain has been good in your area so I suppose that’s out. My parents have several black walnut trees at the farm and they periodically do the same thing - drop fruit before it forms well, leaves drop early, just a general decline in health. The next year, they’re right back to producing (and my dad is right back to swearing how he’s going to take the trees out). Perhaps there’s something cyclical going on - has your tree ever done this before?
Plnnr - who LOVES black walnuts (doesn’t really care for running over them in the truck and then cleaning the meat from the hull, but is willing to do what must be done).
With all of the ‘go see a doctor’ advice we see here on the SDMB is it sort of funny to see someone telling Qadgop to go see a doctor!!!
I sent this thread to a friend of mine who said:
So, if it turns out the end is near for your tree, you may have a nice vacation in your future.
If it turns out that it needs to be removed, please sell the tree! Depending on how big it is, you are looking at a serious chunk of change. However, let it live as long as you can please, black walnuts are beautiful!
I’d take some samples of leaves, fruit (both dropped fruit and fruit still on the tree), stems etc to your local tree doctor. Collect them as close as possible to when you’re going to the tree doctor and seal them separately in ziplock bags.
In the meantime keep the area under and around the tree raked and permanently dispose of anything you rake up by either burning or putting out for garbage collection - don’t put it on your compost heap or keep it in any way. Most walnuts secrete a chemical that discourages other plants from growing under their canopy so it shouldn’t be hard to rake up underneath.
The question I didn’t ask before is are there any other black walnut trees on your property or in your neighbourhood? How do they look? Are they losing their fruit as well?
If there aren’t any others in the district then the chances that you’ve got any black walnut specific diseases or pests are much lower. If there are others, their condition might give you an indication of what’s causing the problems with yours.
A couple of times when I’ve been asked to look at trees that had problems I’ve gone around the neighbourhood looking for trees of the same (or closely related) species to see how they looked. A few times this has given me an indication if there was a problem affecting the whole district.
P.S. Don’t listen to these Phillistines that want to see your tree reincarnated as a couple of end tables. I’ve never seen a black walnut in person but I’m sure it would be much more beautiful growing and thriving than as a piece of furniture.
Poor walnut tree, gets no privacy, always has doctors looking at it’s nuts.
<ahh, the smell of a green walnut>
I have four old walnut trees in the yard and another hundred or so in the timber and park next door, and they randomly drop walnuts whenever. Since I never have a lack of walnuts to hit when mowing in the fall, I don’t generally worry about it.
Regarding taking it down for use as furniture, I doubt it’d be worth it. Walnuts, like a lot of trees, don’t bother to grow anywhere near straight unless they’re competing for sunlight with the trees next to them. Most of the logger types seem to want long straight trees for board making, not stout curvy ones. The stout curvy ones look a lot neater, though.
On the other hand, I have a couple ‘boards’ of 4"x16"x10’ black walnut that weigh a metric arseload and would be spectacular as a mantel or giant bookmatched table… I’ll probably end up using them for firewood, though.
Kidding! You woodworkers are touchy.
Thanks again, everyone. There are no other walnut trees of which I am aware for miles around. We’ve been a bit low on rain, but the damned tree is growing on the primary dune next to Lake Michigan; If it’s roots can go 8 feet down, it’s got all the fresh water it could want.
I’ll tidy up underneath it this weekend, and keep an eye on it. I wonder if tree surgeons give professional courtesy?