Wooly Apple Aphid

I am noticing some wooly apple aphid fuzz on some of my grafts from last year that I brought in and put under lights about a month ago. I sprayed with neem but because I see some fuzz on the roots of some of these I am hoping that there is something that can be done such as a systemic pesticide. These are in pots so they can also be pulled out and sprayed, is that an option at this point?

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Some of the Geneva roots are resistant. Some are susceptible.

G.30 is susceptible. Too bad I bought an apple tree on G.30 (the only apple tree I have planted in my backyard). Dr. Cummins told me woolies shouldn’t be a problem in my area, but somehow woolies found their way to my tree anyway.

I discovered that woolies bounce back between apple trees and elm trees. Too bad I planted a gorgeous Princeton elm next to my G.30 apple tree before finding out this would be a problem. That elm tree is HUGE now (that was the idea). No chance of me spraying that 20 foot high tree.

I doused my apple tree with neam last fall. The woolies were terrible last summer; they have definitely sapped its energy and stunted its growth.

I have read that the only way to really kill them above-ground is to squeeze them between your fingers. Their tiny guts come bursting out and turn your fingertips red! I have employed this method; it is a nasty business.

Apparently getting rid of the roots-chomping woolies is a more uncertain proposition.

Some trees can soldier on despite a hopeless infection of woolies— usually the larger more established trees. My tree is still smallish. I am concerned about it, but I refuse to worry too much. If it dies… then I will replace it with a better rootstock underneath.

Good luck.

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All of mine are on B-9. Above ground I seem to have put the kibosh to them for now luckily I can get to the roots of all grafted trees because none are planted in there permanent spots yet. If I have to I will pull them all one by one and dip them in a bath of neem or volk.

A quick pass with a butane torch is way less messy and much more satisfying; the waxy stuff burns really good.


On the roots though?

So are B9 wooly aphid susceptible? I was looking at putting some grafts on B9 rootstocks.

Awesome! I have these nifty little gas lighters I can use. Great idea!

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This is what I use, it sterilizes pruners also.


No, there’s nothing you can do for the roots except plant on resistant rootstock.

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I grow 100’s of apple trees and manage many orchards. I often see woolys in trees but they’ve never become very problematic- but I don’t mange or grow many trees less vigorous than M7 and my preferred root stock is M111. The literature suggests that it is more dwarfing rootstocks that tend to suffer unless they’ve been bred for resistance and that it is young trees that are most affected.

It seems like about the only thing you could do to save infested trees would be to keep them as vigorous as possible by giving them lots of available nitrogen and removing fruit spurs and flowers until trees reach their desired size (if they do). Encouraging greater vigor is always the last resort and some times first resort treatment to this kind of decline.

Of course, you can probably treat bare roots with an appropriate pesticide, which might help the trees establish. You could even size them up in very sandy soil with a thin plastic sheet spread about 12" deep in the soil so you could quickly dig plants up for treatment.

All this is only speculation, but half the apple trees that I eventually sell are bare root trees grown in a light soil with a sheet of plastic to keep the roots shallow (and capture rain water) for easy and quick digging. Not in any nursery manual I’ve ever read, but I discovered it works like a charm in my soil. If I wasn’t a senior citizen, I probably wouldn’t share this info- I’d be afraid of competing nurseries using it.


So being that my affected trees are in one gal pots it is safe to say that dipping them in a neem bath after taking them out of pots and getting medium off of the roots is an option? I have no problems with aphids on established trees outside. (Knock on wood).

I don’t see why not. I have a lot more of a problem with aphids in the greenhouse- makes plants especially tender and delicious. The tender leaves on green house vegetables can even be damaged with hort oil- which I’ve tried to use for aphids I finally had to use a neonic, which worked for that species. I just can’t speak for how effective neem will be- you know more about that than I do.

Neem oil did not seem to work on my wooly aphids issue last year. It was on some newly planted apple trees. They did not show up at all until towards the end of the season. I may have to get out some heavy duty spray this year or go with the blowtorch method mentioned above.

Torch would surely be a great way on larger established trees. Have not heard much on a systemic insecticide, what is a good one to use?

I asked this same question sometime back, called some nurseries and it seems nobody really knows about B9. Given the fact that the patent holders want to sell as much rootstock as possible if it was wooly aphid resistant I am sure the descriptions would say it.

If these are small trees (assume they are) and on rootstock that is not wooly aphid resistant throw them away and start over. I had one tree last year that I pulled up because it was stunted and learned from the forum that the roots were covered in wooly aphids, Lesson learned - only wooly aphid resistant rootstock going forward.

I’ll have to look again and see which ones these apples are actually grafted on if it happens again this year. Good point. I’d rather do it early enough than to waste 5+ years on a tree that has constant issues. Waste as time and space. Most of mine are on M111 but I do have a few other rootstock choices scattered around. Mostly to see what these different rootstocks do in my orchard. I thought perhaps the wooly aphids were attracted to some type of sweet sap discharge along the a couple of branches. I’ll pay closer attention to the actual trees that are affected this year. If so, out they go!
I’m having issues with all the different Geneva rootstocks I put in. So I’m replacing them with a different rootstock(s) choice for those apples I had on them. That was about 4 years wasted.

I have tried several Geneva Rootstock, G.935 (which not wooly aphid resistant) and G.41. I have one new tree on G.11 and some G.202 rootstock for grafting. Both trees have grown fairly well but they did not produce quickly like I thought they would. Going forward my first preference will be M.111 and second MM106 both are Wooly Aphid resistant for rootstock. No B series rootstock as I cannot tell if they are resistant. I think the tree I threw away was a Red Delicious (which I needed to get rid of anyway - bad tasting variety). I had Wooly Aphids above ground on a Liberty Apple Tree (MM106) - they did a lot of damage.

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I am very disappointed with the Geneva rootstock varieties as well. Read great things about them and thought I chose the correct ones. The issues were not listed as problems to look for. So I’m getting rid of them when I find the apple varieties on rootstocks other than the G series. I even have an interstem that had problems. The G series is just not right for where I am. Maybe it works out for other places.
I may even wait until next year to take scion wood off these trees and try my skills at grating on a different rootstock. I was also looking at the B9 to put a few trees in a smaller space. Only issue is staking those varieties forever on B9. I just never have liked the look of constantly staked apple trees.

An imidacloprid drench is supposed to work well for wooly Apple aphids (and a bunch of other insects as well.)