Deke Sharon said:


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.


1) What are my runty tree's chances?

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.

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?

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

3) Is there anything I can do during the winter to fight these
monsters?

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.

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?

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?

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?

Consider using oil sprays (Organic Method Primer UPDATE).

Any natural pests (the regular aphids on my Meyer Lemon
tree became a tasty snack for ladybugs)?

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)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)