[vron]

Some of our runner bean flowers have dropped off the plants, without there being a runner bean behind it.  
Can any one tell me what has caused this.
I have been told that its to do with bees boring through the base of the flower, instead of their normal way of entry, but I'm not convinced.
Can any one advise please.

[mumofstig]

It means they haven't been pollinated.
French beans set a bean for every flower........... runner beans do not, they have to be pollinated.
I've not seen many bees this year have you 

[granjan]

There are bees that do that.  I had them quite a few years ago and watched them do it!  I spent a long time hand pollinating them with a small brush that year.  You can see the hole at the base of the flower if this has happened.  

If it isn't that, spraying the flowers with water in the cool of the morning and evening can help, if that is possible, and give them as much water as you can.  Also, a small handful of lime to a can of water can help as it enables the potash to be released in the soil.  

[Paul Plots]

...........spraying the flowers with water in the cool of the morning and/or evening can help, if that is possible, and give them as much water as you can...........

Good advice - my 95 year old dad use to do that to the runner beans in hot, dry weather... only go gently with the hose / spray or you will knock the flowers off altogether 

[penance]

Save your energy and water and do not spray the flowers, it does nothing.

Taken from RHS site
'Don’t mist or syringe the flowers with water (as used to be advocated) as this has not been shown to help pod-set. '

http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=381

plenty more infor on the net about modern research showing it is just an old tale.

[granjan]

Save your energy and water and do not spray the flowers, it does nothing.

Taken from RHS site
'Don’t mist or syringe the flowers with water (as used to be advocated) as this has not been shown to help pod-set. '

http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=381

plenty more infor on the net about modern research showing it is just an old tale.

That shows my age   It does talk about the nectar robbing bees on that site though    It very an interesting article.  You're never to old to learn 

[Goosegirl]

I got very interested in this as I had the same problem. It seems to be only a certain type of bee that bores through the base of the flowers and that, later in the year, it doesn't happen as other bees take over.

[JayG]

Sounds a bit unlikely but there is a short-tongued bee which can't easily reach the nectar in runner bean flowers going the "preferred route" (for pollination) so it takes a short cut through the base of the flower instead!

Not much you can do about it, but it is not unusual for beans to not set very well at first, particularly in hot weather. It usually improves with time; just keep them watered, things will improve! 

[andy135]

Maybe it's worth considering planting some sweet smelling attractive flowers on the plot to help entice the little buzzers in there. When my BBeans were in flower, there was little else on the plot to draw pollinating insects onto my plot.

[Spana]

Can pollination only be done by bees?

[Paul Plots]

Sounds a bit unlikely but there is a short-tongued bee which can't easily reach the nectar in runner bean flowers going the "preferred route" (for pollination) so it takes a short cut through the base of the flower instead!

Not much you can do about it, but it is not unusual for beans to not set very well at first,particularly in hot weather. It usually improves with time; just keep them watered, things will improve! 

So that's why my father sprayed his... in hot, dry weather (although it has not been proven to work) it seems to help maintain the flowers longer and give a chance for them to be pollinated...