Hi everyone, new here, and hoping for a successful winter bean crop with a little help from your good selves.
I'm successful with snake beans in the last two summers. Winter beans, notsomuch. The problem I only recently diagnosed: bean fly.
I've planted some Blue Lake and Purple King beans for this winter which are now 5 weeks old. This is my 2nd attempt after my early March planting was wiped out by bean fly larvae.
This 2nd crop was protected by fine netting for about 4 weeks (the lethal stage for bean fly attack), and the plants were hilled with soil to about 15 cm. Now the netting is off to allow for a higher trellis.
The Blue Lakes are doing fine, but I've noticed two different types of marks on some Purple King leaves and can't decide if it is bean fly stings or not.
The confusion might be the purple colour, as photos I have seen online of bean fly stings are yellow spots, not purple. I can't see anything that looks like larvae tunnelling marks, but I'm not sure exactly what bean fly larvae tunnelling in leaves looks like.
Some photos attached.
Bean fly? Or something else?
I've just done a search on bean fly pests. It makes me wonder how anyone can grow a decent crop. There seem to be loads of different enemies for beans. Can't say I've ever had much trouble with most of them, but I guess it depends on what your near neighbours are growing, etc.
My response to problems with pests which attack the youngest plants would be net the crop until the dangerous time is past. I use vege net which is close weave and will stop flies as small as fruit fly. Green Harvest sell it, or you can buy direct from NETPRO at Stanthorpe. If you ever buy from them make sure that the net you get is high UV rated as some will only last a year or so in full sun. Good luck with your efforts.
Thanks for the response Roger.
My net is quite fine and I only saw a few bean flies on the plants when it was netted (this was the first time I had netted young beans).
But good to know I can now go straight to a local business for more nets, rather than handing over more $ to Bunnings.
Interesting you posted this - I have never had any success with beans in winter until now.
I've had great suc cess with Digger's Dragon's Tongue bean.
I've grown it under vege netting (which I don't usually do but didn't want them munched on by wandering creatures), and interestingly, it's in a new patch that the chooks dug up that when I first planted didn't realise the winter sun arc would mean this patch is actually quite cool and shaded for most of the day. Not only the plants have been healthy (touch wood), they have been productive!
My regular green beans (bush and climbing) in the sun however didn't work - one bean and bust. I think these random really hot days were too much for them!
Thanks for your reply. If The Blue Lake and Purple Kings fail me this winter, I'll def give the Dragons Tongues a try.
Any idea from my photos what is on my leaves?
I grow Romano Pole Beans and my primary handicap is usually not being able to harvest them all because many are out of reach.
Hi Mike - not me no but just checked my pest and disease book. They say the most common ones for beans: angular leaf spot (caused from prone seeds) or bacterial blight/leaf spot (wet weather, infects wounds). Looking at the pics a little hard to say for me as not totally experienced at investigation (tend to just assume I've over or underwatered and killed the plants haha), but based on the pics in the book the angular leaf spot seems more like it than the blight? Dunno if that helps
Bean Fly larvae lives in soil in anticipation of a new bean plant growing nearby. Maybe chooks are the answer. I am not a vege growing pro at all, but read up on the bug and it is a real pest.
No doubt about it now - bean fly have been attacking my climbing beans, but they may be mature enough now to withstand it.
Unfortunately the sting mark on the bean leaves look generic - like a dozen other things including various fungal attacks. But then I noticed petiole droop on some plants. When I broke the stem off and examined the join, I found at least one bean fly egg (as shown in the attached photo - the brown thing on the left). One or more eggs must have already hatched and done the damage.
When I know more, I might contribute an article on this problem. Useful info aimed at home gardeners about bean fly is surprisingly scarce.
I least I protected the plants with gauze this time for the first 4 weeks. I know at least that much now!
Thanks for the attachment Mike, I did not know what a bean fly looked like up till now.
That would be wonderful Mike. I'd never even heard of bean fly until your post.
This year has been really bad for them. They even attacked some small madagascar bean plants at my place. My climbing beans are now under net as well.