This year's plague on our cucumbers has been black aphids / Blackfly, so bad I have had to call it quits on the whole crop this week. A few plants started looking badly afflicted in early July, I pulled, bagged and removed them, I didn't think much more about as while we've seen a bit before but it's never been a prolific problem before. I ran the sprinklers a bit more often as I remember hearing that helps knock them off the leaves and they don't live long away from the plant, don't know if that actually helps or hinders really. That seemed to limit the spread for a while but by the end of the last month it had spread further about a 1/3 of tunnel was thick was them. It went through all the rest of them in the last 10 days, every plant is stunted with dead flowers, or completely done for.
Is this a particularly bad year for them? Like I say, we see a bit on outdoors on the courgettes etc taking out one or two plants but never much in the tunnels and never to this extent. From the limited amount I know about them I thought we were out of blackfly season by the end of June?
Any tips on early intervention next time? Our supplier of Phytoseulis at BHGS has recommended Aphiline (Aphidius colemani) combined with Aphidoline (Aphidoletes) next time, presumably with SA permission.
I am thoroughly hacked off as this is the 4th year of pests wiping out the whole crop by end of August, all from things we hadn't been afflicted with prior: Two consecutive years of red spider mite, last year with a really bad case of mosaic virus (vectoring in on aphids?), now it's Blackfly. For the spider mite we'd invested in regular phyto predator applications plus Majestik hot-spot spray when needed. Still not sure if that was actually effective as the last 2 years something else has killed them first. Particularly galling as they were the strongest plants I've raised and the early crop was spectacular in the early summer heat wave.
I am thinking about dumping or drastically reducing cucs from the crop plan next year as all the damn things want to do is die....