I understand that ants protect/move/farm aphids and I wonder if there
are any effective controls that concentrate on excluding/killing ants?

For example, a few weeks ago, I had aphids on my apple tree attended by
ants. If I had excluded the ants (greaseband on the trunk?) would that
have prevented/reduced the problem?

Steve Harris - Cheltenham - Real address steve AT netservs DOT com
A useful bit of gardening software at http://www.netservs.com/garden/