Normally a Runner Bean produces one stem which is the clear "leader" - like this:-
In the axil between the main stem and each leaf a small shoot grows, but it normally remains insignificant unless the main shoot is pinched-out or damaged. In fact some growers advocate deliberately pinching-out the growing-point in order to stimulate the production of side-shoots. I generally only pinch-out my Runners when the stem reaches the top of the cane.
Sometimes the leading shoot runs into trouble, like this one. It has just stopped growing for some reason (pest-related, maybe). It has gone brown and is beginning to shrivel.
However, when this happens, the plant responds by switching its energy to the secondary shoots, ones which would normally remain insignificant. It's the same principle as cutting the main head of a Broccoli plant to stimulate the formation of side-shoots. That's what has happened here. The two shoots next to the bottom pair of leaves have put on a burst of growth.
In this next shot you can see the original main shoot wrapped round the cane at the right, whilst a second one is racing to catch up, and thrusting out strongly towards the cane.
This particular plant won't win the race to the top of the canes, but it may very well turn out to be the most productive plant of the batch.
It will be interesting to hear how that plant does next to the other, unpinched out ones. I only pinch mine out when they get to the top of the cane too.
ReplyDeleteI keep thinking I should pinch my beans this year. As so many of them died and I didn't have replacements. But I figure I'll just do it as normal, just like you do, when they hit the top.
ReplyDeleteLike Jo, I'm wondering if the pinched plant will be more productive - if you get 2 or 3 runners when you pinch off the leader, will that mean you get a bigger harvest per plant? That would make an for an interesting experiment.
ReplyDeleteI just ours - at least some as some have disappeared completely- have developed a strategy for overcoming slug attack.
ReplyDeleteReally interesting point Mark! Thanks for sharing this.. In the past, the deer have (ahem) pinched back my pole beans for me and production was delayed by a week or so, but overall, the plants did thicken up and production increased.. Can't wait to see your updates on this. Niki
ReplyDeleteI'm new to pole beans altogether so thanks for the useful info as I'm growing some this year.
ReplyDeleteWhat about the runner bean called "simpson man stems which has 3 shoots/stems growing directly from the bean/seed?!
ReplyDeleteThey are amazing plants.....ours(scarlet runners) grown from seed in pots inside the kitchen, have been out for 6 weeks now, six plants growing up a six poled wigwam, and having survived the wind last week are flowering and beginning to produce little beans at last. The tops have all been pinched out now. We had a few accidents with the main stems whilst they were inside in the kitchen, but planted them out perservered and youre absolutely right, they compensate and grow another main shoot. Interestingly, only one of six plants has been affected by farming ants and aphids/black fly?, right at the base and it grew another main stem to overcome that. Can't wait to see how many beans they produce, keeping my fingers crossed.
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