Wooly @^%@&^# Aphids

First of all, howdy. I've been lurking for about a week, and very much like the tone and content here. I'm a long time user of newgroups (specifically rec.music.a-cappella, and alt.music.a-cappella back in the early 90's), and it's nice to find a new community for a my new hobby (now that I have a garden).
Onto the question (the first of many, I'm sure):
I live in San Francisco, and recently (April, 2003) bought a house with 3 dwarf apple trees in the back yard. All were infested with wooly aphids. I like to keep an organic garden, so I was told by several sources that my best bet was to squirt them off with a hose.
And squirt I did. All summer and fall. It was like a carnival game, but the balloon never popped.
I kept the trees clean, and yet the little monsters would come back. At first every day or two, then twice a week, then once a week, and now I hardly see them.
In the summer, the sunniest tree was covered with leaves, and by fall it provided a nice harvest. The largest tree, second sunniest, was covered with leaves, and sent up some verticle shoots, but never bore fruit. I'm bullish that it'll be in full force next year.
However, the third tree, the runt (3 feet high) and least sunny of the three, is still a sad sight. A few full-size leaves, and some tiny ones, but mostly a skeleton.
I understand wooly aphids go underground this time of year, attaching themselves to roots. It's not unlike the Alien from the movie of the same name - keeps changing form, keeps coming up with new ways to make your life miserable.
All of the builds up to the following questions:
1) What are my runty tree's chances?
2) If it's likely to die, would I be doing my other trees a service by pulling it up, bringing the root-born aphids with it, or would they jump ship and go bother my other trees?
3) Is there anything I can do during the winter to fight these monsters?
4) Next year, what should I do to hopefully be rid of them once and for all? I read somewhere that the'll change form once again, and send crawlers up the trunks. Is this right? Will fatty acid soaps do the trick (they're not much effective when the aphid is in "wooly" stage, protected by the "wool," but will that be gone in the next incarnation? Any natural pests (the regular aphids on my Meyer Lemon tree became a tasty snack for ladybugs)?
5) Anything else I should know?
Thanks! - Deke Sharon
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Deke Sharon said:

A badly located tree is never going to thrive. It could struggle on for quite a while, attracting pests and requiring extra attention. It might be best to pull the plug.

How long is the crawl over? Is the runty tree upwind of the others?

The Organic Method Primer UPDATE suggests gently digging around the base of the tree looking for aphid galls on the roots, which can be pruned away and destroyed. It also suggests using beneficial nematodes to attack any colonies on the roots.

According to what I just read, they have an alternate host on elm trees, which they feed on in the early spring for two generations before moving back to apple trees. (Underground root-gall colonies are continuous.) Any elm trees in the neighborhood?

Consider using oil sprays (Organic Method Primer UPDATE).

Same source noted above: Chalcid parasitoid wasp, _Aphelinus mali_ syrphid flies ant lion Clover is recommended to support enemies of the aphid.
[I 'rescued' a plum tree on the property that was badly infested with scale; another was too far gone. However, the tree is not well located and still struggling. And varmints eat all the plums that the bugs don't get. Thirteen years and it's still hanging on, barely...]
--
Pat in Plymouth MI ('someplace.net' is comcast)

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Thanks for the lengthy, thorough response

It has fruited in years past, but that doesn't mean it will.
A related question - were I to plant a new fruit tree in its place, would I be wise to stay away from apple (or pear?), so as to not give the aphids a new similar food source?

from tree to tree? Perhaps a yard. This is a San Francisco backyard, after all ;)

yup
Ah - good suggestion. Probably not a backyard chore while my 3 year old is around. What nematodes does it suggest.
And wht is the OMPU $200 on Amazon?!?

The closest possible one would be in Golden Gate Park - a minimum of 2 blocks away.
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Deke Sharon said:

IMHO yes, so as also to give yourself an alternative fruit!

A, sounds doable.

Very doable....

Oh, they don't harm people and applying them involves pouring or spraying solution and then watering them in. Might even be fun.

Doesn't mention specifically. I the Hh or Hb species are better at going after underground insects. (The Sc nematodes are better for near-surface.)
Another thing you could do is give the trees some TLC in the form of foliar feeding (with seaweed spray -- I use Maxicrop) and mulching with compost.

The culmination of the life-work of Bargyla Rateaver, self-published, low-volume. She is elderly and the book sales have been a source of income.

Close by, then, in terms of a generation of flying aphids.
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Good idea.
New question - what fruit?
I live in the "Inner Richmond" - Just north of Golden Gate Park, due south of the Golden Gate Bridge - 10th avenue and Balboa, for those of you who know the city.
Currently, I have:
Mission Fig 3 Apple Trees (European) Pear Loquat Meyer Lemon Haas Avocado Summernavel Orange Calamansi Lime Keiffer Lime Pineapple Guava Passion Fruit Vine
I also have an assortment of herbs and some vegetables (carrots, this season).
This isn't a large back yard - basically a rectangular lawn with fruit trees surrounding. I just happen to like planting edible plants (which is why I'm reading RGE now)
What would make a nice addition? Based on the location, it would need to be a tree (not the sunniest part of the yard, so to get year-round sun it will need to be 3 feet tall).
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