Thursday 18 June 2015

How to Protect Broad Beans from Blackfly


Hopefully within the next couple of days I'll be harvesting the first of the broad beans.  I would usually already have had a crop from the polytunnel but regular readers will know that the mice put paid to that idea this year.  Mice are not the only pesky pest trying to get to my beans before me and I noticed, yesterday, that some of the beans had some blackfly on them.

Blackfly or black bean aphid (Aphis fabae) are a species of aphid that love to feed on the tender tips of broad beans and can increase rapidly to the point of even killing a young plant and certainly weakening all plants they infest.  They can quickly spread from one plant to another helped by ants.  The ants feed on the sticky honeydew that blackfly secrete and they have "learnt" to move aphids to new plants in what can only be described as a form of farming.

Broad bean tip infested with blackfly
Young pods infected with blackfly

Because blackfly can be so damaging to a crop of broad beans it is vital that they are quickly controlled.  The simplest method is to be vigilant checking daily for an infestations.  Infested bean tips should be nipped off, together with any offending pests.  If you are not squeamish you can also squash off any blackfly that are further down the plant or that have infected the pods, their second favourite haunt.

Tip removed to show blackfly

Ultimately prevention is better than cure and there are various methods you can employ to keep blackfly numbers down:

7 tips to prevent blackfly infecting broad beans


1. Ensure you have a well manured soil to allow healthy plants to grow that are better able to withstand an attack.
2. Encourage insects and minibeasts in your garden that feed on blackfly including ladybirds, lacewings and hoverflies.
3.  Keep down the number of ant nests in the garden.
4.  Remove the tender bean growing tip before an attack takes place.
5. Be vigilant and check your beans daily.
6.  Blackfly also infest other plants such as nasturtium and weed species such as dock and fat hen.  Keep other susceptible plants away from your beans and keep on top of weeding.
7.  Grow your beans as early as possible (mice permitting!) so that the plants are bigger when the blackfly first attack and better able to survive an attack.


Fingers crossed then I have saved my broad beans from death by blackfly and will soon be eating these delicious veggies ... although my friend JT is no doubt shaking her head in disbelief that anyone can actually LIKE broad beans!!  However look, JT ..... I have actually managed to harvest cucumbers from the plants you and Mr JT gave me.  They may not be huge but they are really tasty.  I have always struggled to grow cucumbers well and was not even going to bother this year until Mr JT gave me 2 plants.  Glad I didn't give up on them and fingers crossed there are more plenty cucumbers to come.

MY cucumbers!!

Are you a vegetable grower?  Have you any tips for growing great broad beans or cucumbers?  



28 comments :

  1. have successfully dealt with blackfly on broadbeans by blasting them off with water - hose or sprayer - that way no nasty chemicals and you dont have to cut the plant back

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  2. I've only ever grown chillies, does that count? The cucumbers look great, home grown always taste better. My dad used to have an allotment and his veg was always much better than shop bought.

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  3. Fascinating how the ants and the blackflies work in a team (but they didn't know they had you to deal with and foil their plans.) I'd love to try and grow cucumbers some day as my family insist on slices in their sandwiches.

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    1. Mmmmm - cucumber and Marmite sandwiches, a taste on my childhood and something I look forward to every summer!

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  4. EEEEEE you said the 'A' word!
    I can't abide a..a...ants *shivers*
    I'm pinning this to my gardens board Rosie - really helpful, you are a good egg sharing your knowledge like this.
    Broads beans are the best *day dreams of broad beans, crispy bacon and a knob of butter*. See no actual tips on growing them - just eating them!

    Thanks for joining in again Rosie! x

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    1. I'm not keen on ants, especially the red ones which bite ...
      I've just picked and frozen the first of the beans, although I have to say a fair few went straight into my tum fresh from the pod. So good they were!

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  5. Great advice - last year my broad beans had a horrendous blackfly problem because I didn't pinch out the tips quickly enough. I swore to be vigilant this year and pinched out earlier but the pesky things are still there again, albeit in smaller numbers though. I'm going to try the water blasting idea this weekend!

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  6. Some great advice here :-) We struggled with black fly the first time I attempted a veg garden. I have been a lot more vigilant in future years :-)

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    1. Vigilance is the key otherwise they can take over so quickly.

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  7. Your post has come just in time. I have lots of blackfly on my broad beans and I've decided to take action this weekend! It's amazing how quickly they've mobbed the plant. Broad beans are my favourite bean so I'm determined to stop the little critters. Great post, nice cucumbers!

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  8. My nan used to dilute washing up liquid and squirt the blackfly with it, no idea if it worked, just recall her doing it....lol

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  9. I love broad beans but I've always been put off growing them because of blackfly. I think I'm going to have to start seeds off inside next year to get them in early. My mum always cooked them whole straight from the pod but my husband makes me shell them!

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    1. If you pick them young you can eat them whole but I prefer to pod them - just do it before they get too big. If the bit where the bean was attached to the pod is black you have left it too late and the beans will be tough.

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  10. Broadbeans are lush, hope they are saved. Those blackfly are so bloody annoying, thanks for the tips!

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    1. I have just harvested the first lot! The were delicious and I have frozen plenty for later.

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  11. I tried growing various veg in our other garden but I found it to be a lot of hard work for very little reward. Our potato crop was rubbish and I felt guilty about killing the eggs that the butterflies laid on the cabbage so they were left for the caterpillars! In our new garden, I'm just growing flowers!

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    1. Some flowers are edible too! Veggie growing is hard work and everyone has failures but the taste of fresh produce can never be beaten and makes it all worthwhile for me,

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  12. I saved this blog so that I could comment when I had more time. Broad beans and vege growing - a subject close to my heart! I know in Australia I blast the aphids of roses with water, and use dish washing liquid as well but it is not so effective. Are there any natural predators that will eat them (apart from the ants!). I grew up on a farm and I used to loath broad beans, but grow them nonetheless. Mum would force them down. But I've just found out that they are Feves! There is a great recipe in one of my earlier blogs - (sorry if I'm repeating myself) http://www.agathabertram.com/tis-the-season-for-feves/

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    1. Will have a look at your recipe later - in the meantime there are lots of predators that will eat blackfly including ladybirds and the larvae of wasps, lacewing and hoverflies. The ants don't actually eat them, just the honeydue they secrete.

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    2. Ok, tks. Can I garden vicariously through you? Are these worse pests than the ants? No need / hurry to reply if you are actually gardening - I live in an apartment and don't have a garden so am excited for those who do :)

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  13. Have pinched out the tops of my broad beans and this seems to have completely prevented an infestation of black aphids. Am keeping a close watch on the beans, but so far, so good and a huge difference compared with last year when I didn't know about this technique!

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  14. Is this post still alive? What does it mean to pinch put the tops of broadbeans? I am battling aphids (same thing?) in Australia now!

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    1. Hi - it means to cut off the top few inches/cms of the plant as this is the softest part of it that the aphids like to eat.

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