Cucumber woes: aphids

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John English
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Joined: Sunday, 6 May, 2012 - 11:37
Cucumber woes: aphids

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....

 

katecollyns
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Joined: Tuesday, 23 March, 2010 - 11:21
cues

which varieties are you growing John? I only really bother with marketmore now which are affordable in case of seed failure, & seem pretty bullet-proof. Appreciate the thicker skins might not suit all markets though...

Cheers,

Kate

John English
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Joined: Sunday, 6 May, 2012 - 11:37
Varieties

Hi Kate,

Varieties are all midi size F1s, Passandra, Khassib and Akito. Khassib from Rijk Zwann was a replacement for Melen as I couldn't find seed this year, good variety and great yield while it lasted (ought to be good as the seed isn't cheap...)

The thicker skinned Akito ridge variety held out for longer against the aphids but it was so severe it was only a matter of time. Will have a look at Marketmore and maybe give them a trial.  

Will probably do more cucs next year but maybe just half a tunnel this time. I am reluctant to give them up completely as demand is high and they are a good earner and an easy sale, can easily sell a steady 500-600 a week and shifting the bigger gluts isn't too much of a problem either. If investment of £80+ a month in aphid and spider mite controls is what's needed to keep them going into the autumn then may just have to bite the bullet and do that.  I need to do some costs and returns calcs....

philsumption
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Joined: Friday, 11 December, 2009 - 17:12
Bringing in the bugs

Hi John,

I think you need the Hankham approach of encouraging your beneficials https://www.agricology.co.uk/resources/buildings-machinery-roots-horticulture-pests-diseases/bringing-bugs

There is a lot you can do in regards manipulation of climate that will affect pest and predator poulations one way or another - see here. Overhead irrigation is essential to keep red spider mite down, for example. RSM will get ahead of the predators (especially Phytoseilus) in hot dry conditions, which also means it is worthwhile having a mix of predators in there.

 

John English
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Last seen: 3 months 2 days ago
Joined: Sunday, 6 May, 2012 - 11:37
Thanks Phil, very useful

Thanks Phil, very useful resources there and food for thought for next year. John

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