Maybe you should apply it as a spray. I use Discus (Merit/Marathon and Decathlon mix) on River Birches for aphids and it offers extremely good control. Soaps and oils just don't cut it, because the aphids are often inside the curls on the bottoms of the leaves. Discus is availabe to homeowners under Bayer Rose & Flower Insect Killer. I've used imidacloprid in turf before, and dug there a couple of months later and still found earthworms. If it's highly toxic to earthworms, it will say it on the label. That said, on the Merit/Marathon label it says that imidacloprid has properties similar to chemicals that have been found in ground water. Also, insects can become resistant to imidacloprid if used too often without rotation (all part of IPM).

For the most part any damage done to the soil life will recover if you are going to use a sysntemic insecticide on a limited, short term basis.

I also have a river birch in my front yard. It is not in a good spot as river birches want wet soil, not dry like my front yard.

Throughout my area I see a lot of river birches being planted. Most don't last more than a couple/few years, but some, for unknown reasons, do really well.

One of the principles of IPM is site selection and proper plant choice. You may want to give some consideration (sounds like you already have) to replacing the tree. You *could* try another river birch if you really wanted to. I don't know why some make it when many don't.

In my case my RB is on it's 3rd year in my yard. Last year it dropped it's leaves 3 times. It was 3 trunks, now it is 2, the weakest died.

This year I have sprayed repeatedly with Safer bioneem. There are no mites or aphids on the tree. About half the leaves yellowed and dropped anyway. And we are just getting into the hot dry weather here. If this tree doesn't improve by fall it will be replaced. I am simply not willing to baby a tree with persistent troubles.

It is much easier for me to replace the RB when it is 12' tall than when it is 40' tall. It is also pretty fultile to think you are going to keep spraying in a 40 tree.

I suspect your insect problem is not the problem, but symptoms of the problem.

Thanks for the input User and Stomp. Very good points. Here's a couple of other thoughts.

First, it is not a river birch, it is a grey birch, Betula populifolia or something like that. I know birches are notoriously buggy and they all get scale, borers and aphids. The main reason the aphids on this birch are such a concern is that it is very small, so the level of attack is almost completely defoliating it. I had hoped that by planting this native tree in a relatively good spot it wouldn't suffer from all the problems birches are famous for in suburban areas. BTW, I don't live in a suburban area, I live in an urban area, where you rarely see birches, especially the white barked ones. There is one in a yard up the way from me and that was my inspiration.

The bed is very small, maybe 6x6. The tree is small, maybe 4 ft. max. There's a lot of room to go up but not out. That's why river birch is absolutely out of the question. Grey birch is one of the smaller birches. The smallness of the bed is the reason I'm worried about killing worms and other beneficial soil organisims. If it was a larger area, other worms and beneficials could migrate into the soil once the insecticide wore off and recolonize. But I don't know about it in this case because I don't know how long these systemics persist. I lost my glasses but I have tried to read the fine print and it doesn't say anything specific about earthworms. It does say it is highly toxic to humans, birds, fish and pets. And it says you don't want it to get into the groundwater. That's not too likely given the siting of my house and the small level of application I am considering.

But the larger question is whether this tree is ever going to thrive or if I am just signing on for something that is going to take continual fussing with. I can tolerate some bug damage but in my small yard this is a specimen tree and I don't want it to get too ugly.

I've had a hard time coming up with an alternative since the area is very sunny and I need a small, fastigate tree but one that will give some shade. Ideally I want something umbrella shaped. I have considered Ironwood, Carpinus carolinia as an alternative, but I don't know if that won't be just as buggy. I have no experience with this tree as an ornamental. The most trouble free trees so far in my yard have been the fireglow japanese maple and a small crab apple. Considering the sun my yard gets I am wondering how I've gotten so lucky with the maple. On the other hand, I only have four trees planted, the birch, the maple, the crab, and a japanese silverbell which has been ho hum. I hate to do a repeat just because this tiny patch is all I have to indulge my passion for trees and other plants.

Hmmm.. my apologies for thinking you had river birch when you clearly said grey.

One thought, since the tree is so small is that you have at least a few years before removal becomes an expensive (have to hire someone) solution.

Instead of using a systemic insecticide why not give neem products a try? This is what I use for aphids and other soft bodied pests and it works really well. Like I said my river birch still drops leaves, but this only indicates to me it has troubles beyond insects.

If you aren't familiar with neem, it is a botanical insecticide from the seeds of the neem tree. It initially acts like an insecticidal soap in that it smothers or dehydrates the soft bodied things like aphids, but it also coats the leaves an acts as an anti feedant. Any bug that still takes a bite or suck becomes unable to reproduce. Adults can't lay eggs and larvae/nymphs can't become adults. So, can't feed and can't reproduce = goodbye bugs.

It is believed that *some* plants absorb the material into themselves and it has systemic properties, but I have never seen a list of which plants neem has a systemic function with. It provides protection for around a week, or until a good rain.

Neem has actually been shown to be beneficial to worms, dunno why. If it is beneficial to worms the odds that it harms soil life seems remote. Worth a try.

I am using a product called Safer (brand name) BioNeem. It is an extract of the insecticidal ingredient in a light oil base (like a summer or horticultural oil).

There is some concern that neem can cause damage to beneficial insects if they are sprayed directly, but overall neem would be among the least toxic solutions if you aren't getting effective control with insecticidal soaps which only protect for a minute or two.

Straight neem hasn't lived up to the hype. That's why they're pushing the extraction, azadirachtin, which is a first-class insect growth regulator on soft-bodied insects in my opinion. It keeps insects from advancing to the next life cycle stage. A rep from OHP mentions that existing adults can still reproduce, but the new hatching larvae will be stuck in that nymph stage and eventually die. The only thing neem oil really worked on for me was Japanese beetles, probably because the smell repelled everything for a few days, even customers.

As far as the health of the tree is concerned, I'm a firm believer in plant selection and planting practice. Putting the right plant in the right spot is half, while the physical planting is the other. Trees poorly planted or poorly cared for during establishment may take many years before they thrive, if they ever do. Some trees planted poorly may grow well for several years, only to end up dying from something that may have been linked to the installation.

-- Straight neem hasn't lived up to the hype. --

I agree and I wouldn't expect it to. Straight neem is marketed for a wide range of purposes from plant protection to toothpastes to makeup to health concoctions etc.

I really doubt that the neem being offered for horticultural purposes is any different than the neem offered for human health purposes and as a result I doubt it is at all standardized for azadirachtin.

So, one order may work wonders and the next do nothing.

That's why I go for the extracts. You always know what you are getting.

I did some Internet research on the neem oil and did read up on the difference in concentration of the important compunds related to the extraction methods. I couldn't find a reliable source for a good neems spray right away, but since I work for an organic farming research facility I will get with my colleagues and find a source. Meanwhile, I used the dysyston because I had it. I looked at the EPA's web site and it said it was only "intoxicating" to worms and also it doesn't persist for years and years, at least as best as I could tell, so I'm willing to give it a try. There is room in the bed for the worms to leave the vicinity temporarily if they don't like the conditions. I also realized that part of the reason the leaves were floundering is the oil I was using was scorching them.

As to the larger question of right tree right spot to thrive, this had been a continual battle/problem for me to solve. I've hemmed and hawed for over a year about this. The condition, in my urban yard, is very harsh. The soil I have amended and worked on to be relatively OK, which is why I guard its fertility so jealously. But the other conditions over which I have very little control are bad. There are virtually no other trees in the vicinity of this urban situation to ameliorate the hot dry microclimate. The reason for this is there are a lot of power lines overhead and square footage is limited, making trees problematic. There is lots of cement and ashphalt that absorbs and radiates heat. Plus this is southern exposure so it gets strong afternoon sun. The bed is small so the fertility resources are also small. And because it is a row house, it gets a bit of a wind tunnel effect. Now, small trees are usually understory trees that will not thrive in these conditions. Trees that thrive in these conditions are not necessarily small, or umbrella shaped. Hence the paucity of trees in this neighborhood. The only broad leaved trees I've seen around are dogwoods, flowering cherries, japanes maples, and a mimosa tree. And the one birch I mentioned. Even going back to the "tree drawing board" leaves me thinking about trees native to the hot dry steppes of Mongolia I think! :-)

I have never seen a warning on a pesticide label regarding earthworms or microorganismns! Some resources indicate that the active ingredient in Merit(imidicloprid) is very toxic to all kinds of non target organisms, including earthworms. We have a lot of studying to do with this product, but it appears that it is insidious in its long term effects.

By the way, plain old Sevin is one of the very worst in regards to earthworms. There are no warnings. There are many commonly used chemicals that are highly toxic to worms and microorganisms...and if that kind of information is important to you, it is available on the internet.

The chemical companies are not going to put any information on the label other than what they are obligated to by Federal law.

I don't think that Dysyston is labeled for outdoor use (anymore), but am not certain of that. I would hold off on using that until you can gather more information. For one, you wouldn't know how much to use. You could try the 800 number that will be on the label!

Well from what I gathered from the EPA Web site, Dysyston is not even recommended anymore or made anymore, the permit ran out, whatever. The only thing I did see was I think that Dysyston was less persisent than Merit, which I got the impression could persist for two years. And I agree rhizo, that most of the time there is very little comprehensive information available on these chemicals. They are not tested comprehensively. The biggest concern is their toxicity to humans, not soil microorganisms. Heck, we don't even know all the types of soil microorganisms that exist, let alone what pesticides are how toxic to them. But I have to weigh this question with how bad is it to treat one tree in a tiny urban yard. I'm not broadcasting this stuff all over my lawn. But as has been discussed here, a topical systemic might be better for this particular application.

Know, too, that you are discussing a plant with strong associations to a wide variety of insect pests. ;-( Given that disposition, and the difficult growing conditions you've described, I'd say that you have your work cut out for you.

you might want to look around to see if you don't have another problem that goes along with your aphids/ants - namely - fungus.
i've seen several problems that start with birches - which if planted in lawns usually get a bit overwatered - and if the environment is right - mushrooms beging to grow around the base of the birch, and inside the trunk - from the ground up. this produces a great hangout for both aphids, and the ants that "farm" them. it'll kill a birch slowly (couple 5 years or so).

small ecosystems are fascinating things as they destroy the plants we love. one ailing birch in our yard, before it had to be removed due to this problem, was found by a woodpecker who bored into it looking for tasty insects. next, a pair of western blue birds moved into the woodpecker-made hole, and fledged 5 clutches of young ones in a three year period before the tree had to be removed.

the birds brought us great joy, but we were quite sad to lose the tree. lessons learned - what to plant where - and what not to overwater. if we do it right to beginwith, we don't have to run 'round ruining our soil.

Well, the birch recovered after the Dysyston and a small shot of fertilizer with healthy leaves. Third releaf of the summer. But since I'm moving and will not be living there much longer to baby this tree I dug it up and brought it with me to the north country. What I planted, carpinus carolinia probably won't do much better in the heat and sun. I should have not hacked up the mimosa that was growing along my foundation and just transplanted that volunteer sapling!

You bring up another reason the birch had to go. I couldn't afford a pest vector in my tiny yard. Out in the country I would have just let the birch do its thing, come what may. Here's a shot of the tree before I took it out, so you can see what I mean by "tiny" yard. The little birch is growing in front of the green lawn chair.