Update - Grey Aphids. - I killed off the grey aphids using the blast-jet on the hose. It does work, sort of, but within hours the plants are moderately re-colonised, and within a week its back to where it was again. Sometimes not even this long - one kale was re-infested within 2 days. And water blasting isnt something Id want to do every two days. Water blasting works to get rid of catastrophic infestations, but not as a regular routine maitenance. A tip - obvious really - try ot take your pot plant from the area it normally lives in, and blast it somewhere else. Otherwise the bugs just climb back up. One also finds that there are colonies of grey aphids on the leaf undersides and these just recolonise.
I am going to try using a spray similar to what Ive
tried, but apply it after Ive finished with the blast-jet hose. So apply
it to a clean kale and see if a spray works as a deterrent. (It
certainly worked as a deterrent on the cabbage moths, but not on their
caperpillars, although I must admit Im not sure in what state of
disrepair the spray actually left the cabbage moth caterpillars in).
UPDATE: a week or so later.
have been water blasting the Kale, but the grey aphids come back after a
few hours. I am tending to the view that I might get rid of all the
mature kales now, and allow the new batch of kales Ive planted to have
the best chance of success and be aphid free. There is enough kale on
the adult plants for a few weeks, but I think I need to purge it all;
eat whats recoverable, and leave the rest. This will create a gap of
about two weeks of meagre salads before I have enough from the seedlings
to get a decent salad. I am also contemplating nuking the small salad
pot plants, because they are overgrown with caterpillars, when the
caterpillars were rampaging in February, and I was not doing a lot to
stop them. I think I'll chop and drop the foliage and let it try again.