My red currant is severely infected with Blister Aphid, or what I think are blister aphids… I spray with oil in dormant season, and with insecticide before the bloom. But every spring it starts with few leaves I try to pick and discard out of the yard, and by June whole bush is just covered with bad leaves. This year I noticed few leaves affected on gooseberry and black currant - something I never saw before. What is strange, when I pick a bad leaf and look underneaths, there is nothing visible or touchable to smash there - are they really that small? Or I have some other issue and treat the wrong enemy?
Did you try a magnifying glass?
No, I didn’t, but I do not feel anything under fingers as well. How small they are?
Good point, aphids would create a slickness when there bodies are crushed and they also deposit the sap outside the leaf. It’s always been aphids when I’ve seen the blistered leaves so I have no clue.
OK, it is aphids. I couldn’t feel them because they are not in the blister area, they are on undamaged part of the leaf and they do not make that sweet mess as regular aphids do. Also, unlike other aphids there are just few of them per leaf, so you don’t feel them. I can even see their eyes under magnifying glass and on the picture.
So, how to deal with them?
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Thanks, that is interesting.
You can spray them with hort oil if it’s not too warm (in the '90’s or higher). I’m assuming you don’t want to use pesticide or you wouldn’t be asking. A hard spray of water might even work.
I use Worry free, does it count as pesticide?
ACTIVE INGREDIENTS:
Pyrethrins… 0.30%
*Piperonyl butoxide… 3.00%
Other Ingredients… 96.70%
TOTAL… 100.00%
It does kill feeding aphids, but what I really want to do is to find the strategy that allows me to keep leaves undamaged, what I can’t achieve so far with dormant and spring spraying…
You kill them before they damage the leaves, as you can guess. Now you know when you must monitor for them and how small they are. Of course a little leaf damage does no real harm- I would just wait until I see some damage and worry about other things myself.