River Birch question

[fishin_spooge]

Why are my river birch trees leaves turning yellow and wilting on some of the branches. I water them enough but not too much, plus it's been raining like crazy. They are about 6' tall variety. They do see a lot of wind as my property doesn't have a ton of trees still but hard to believe that's the issue. Any help appreciated.

[Steve Foss]

There are a lot of reasons the leaves could be turning and withering. If you have a digital camera, can you take three pics? Closeup of small group of affected leaves, medium view showing the whole tree, and a wider view showing the setting, as well.

That'll help us a lot.

[Powerstroke]

Lots of different reasons associated with river birch. If you're watering even with the rain, I would stop. Birches also have a lot of pests and diseases that wreak havoc.

Do you have a picture?

Typically, river birch that are healthy aren't bothered by pests.

[fishin_spooge]

Maybe the roots of my trees aren't getting enough water, I don't think they have any of the diseases I see on the internet or any of the insects. Hard to say, the maples I planted are doing fine. I'll get pics up most likely tomorrow.

[Powerstroke]

Unless you got plastic over the roots, they are getting enough water. There has been no shortage of natural water this year.

[Steve Foss]

It'll be interesting to see the pics. A strong possibility is iron chlorosis due to higher pH. Birches in general seem to thrive best at pH levels of 6.5 or less, and river birch is susceptible to chlorosis. Not sure what typical soil pH levels are around the Twin Cities, but I've seen trees suffering from it down there. The river birch is very resistant to the bronze birch borer, so that's good, and they are somewhat tolerant of drier conditions.

Or it could be something completely different. Wilting is not a typical symptom of chlorosis.

Not a bad idea to get your soil tested anyway. The results can serve as a guide on what to plant and not to plant. Andy may know of a good place in the Cities to get that done.

[delcecchi]

Here is web site with some information.

http://www.extension.umn.edu/distribution/horticulture/DG1417.html

They say very low susceptibility. Also give some growing information. Die back can be a result of last summer dry weather too. How long has the tree been there?

http://www.na.fs.fed.us/spfo/pubs/howtos/ht_birch/ht_birch.htm

is another site.

quote...

In the forest, birch trees thrive on cool, moist soils. Their very shallow root system makes them sensitive to even short periods of drought or heating of the soil, thus they grow poorly on hot, dry soils. Therefore, homeowners should attempt to place birch trees in locations where the soil will be shaded, cool, and moist. However, birch trees require full to partial sunshine on their leaves to grow well. The challenge is to select a growing site where the soil will remain cool and moist, but where the tree will also receive full sunshine on its leaves for much of the day.

....

Soil acidity - Birch trees do best on slightly acidic soils (pH 5.0 - 6.5), though the white-barked birches especially our native paper birch-are capable of growing well on alkaline soils. River birch often develops iron chlorosis (yellow foliage) in alkaline soils and should be avoided as a tree selection in most cases where the pH is greater than 6.5. Slightly alkaline soils can be made more acidic if you add soil amendments, though it can be difficult to maintain the soil pH over the life span of a tree (discuss this with your county extension agent). Soil tests can be obtained at many county extension offices and some nurseries.

end quote.

[fishin_spooge]

I showed my neighbor the trees this afternoon and he said that iron chlorosis was a good possibility and the same thing happened to him. I'll get the pictures on tomorrow afternoon after work. He said he put some fertilizer on them for azeilias and hydrangeas that was acidic twice a year and that turned his around completely. The trees have only been there about 2 months, got them from Home Depot and they stand about 6-7 feet with about 4 trunks per clump. I bought some of that fertilizer and watered it in tonight.

[Powerstroke]

I didn't even consider chlorosis, but that's a very logical possibility. We do get a lot of chlorosis in the metro. Usually it involves oaks, but if the shoe fits....I especially like the part about your neighbor. It sounds like he added sulpher to alter the PH, but if it helps than it may be a PH issue that is affecting the soil and its trapping the iron.

If the product you use doens't perk them up in a couple weeks, check out iron chelate. Tell anyone at a quality garden store than you need iron and they will help you out. You just mix it up and pour in the root zone of the tree. Your lawn will green up like crazy too.

[Dotch]

Just a guess and yes we have a river birch that's 15 - 20 years old, but it could be based on what you've described, birch leafminer. We've had some issues occasionally over the years with it. This is Jeff Hahn's latest info sheet on the pest from the U:

http://www.extension.umn.edu/distribution/horticulture/DG6134.html

Our river birch has iron chlorosis big time this year. Soil pH's around the TC area vary but they tend to be more acidic than here. And, our subsoils tend to be more alkaline the deeper one goes in the profile. This is typical in MN especially as one moves further west. I also suspect as we've found with iron chlorosis in soybeans that there is a nitrate nitrogen component to the equation as with warm springs, we tend to get more mineralization of nitrate N from the soil organic matter. The rains in June have moved that high concentration of nitrate into the root zone in the soybean fields. It inhibits the conversion of iron to the preferable form (ferric or ferrous I can't recall this time of nite without looking it up). I have no reason to believe the same wouldn't be true under a susceptible tree, judging by the rate of growth of the grass without supplemental N. The wilting as Steve said does not appear to fit with the iron chlorosis possibility. Good luck trying the fertilizer approach though. Hope it works for you.

[Steve Foss]

If it is iron chlorosis, it takes a long-term effort to amend the soil enough to keep pH lower. You're essentially trying to create an island of lower pH in the middle of a sea of higher pH, and you'll be fighting the water table, which has a large impact on local pH.

Adding iron supplement is a very effective solution, but may be a temporary solution. The larger and older the trees get, the more costly and time consuming it is to maintain their health by amending soil characteristics or adding supplements. I once treated a mature maple out in central N.D. for IC using both methods mentioned, and it cost the homeowner hundreds of dollars to get the tree looking healthy, and it did not last. His wallet ran out. I suggested such would be the case, but he went ahead anyway because he had a lifelong and strong emotional attachment to the tree.

If, and again that's an if, your soil's pH is too high for the river birches, it's much more sensible (you'll be money and time ahead) to pull them (or resell them to someone to move, since they're barely established, and bring in trees more suited to the soil.

But that's still speculation at this point.