Ive got cucumbers in a grow bag in a greenhouse, last year in the same position they were great, lots of fruit and no problems, this year they are being treated exactly the same but after the fruit has developed to about 1" long it turns yellow and wilts (or rots?).
The leaves look OK and there is no obvious sign of pests or diseases, any ideas please?
Any sign of pollinators, e.g. honey bees?
I would suspect lack of pollination. This could be due to lack of pollinators visiting the plants, or due to a lack of male flowers.
Some cucumber cultivars are gynoecious (bear only female flowers), and require another cucumber cultivar to pollinate them. Usually seeds for a pollinator variety are included in packets of gynoecious cultivars. Home gardeners growing only a few cucumber plants risk not having enough plants to ensure one of them is the pollinator cultivar.
Cucumbers cultivars can also be parthenocarpic (set fruit without pollination) and these cultivars are ideal for greenhouse growing.
Most of the types we grow do not need to be pollinated, so that's a good tip. How is the watering going if the fruit are rotting?
No, I think that inadequate pollination would still be a prime suspect.
Either most of the blossoms are not being properly pollinated or the cucumber vines are aborting the fruit because they are under stress (examples: disease, lack of some particular nutrient, too much shade).
It's easy to find out, cut one (yellow cuke) in half and see if there are any seeds. No seeds, it didn't get pollinated and it's being aborted.
Newb
New info...Thanks
It would be a little early to expect seeds.
No it's not. This type of forensics may require visual aids such as a magnifying glass, depending on how good/bad ones vision is. If one knows what a seed pattern in a cuke, watermelon, etc looks like, finding that pattern on a smaller scale is dead easy.
I learned this trick from Master Gardener Cisco Morris. You can discuss it further with him if you like:
Newb
You're welcome. I learned that from a local Master Gardener who has a radio show on the weekends. I called him about this a couple of years back and that's what he told me to check. I did, it had no sign of seeds meaning we had a pollination problem. So I called a friend who raises honey bees and he placed a few hives on our property. End of problem, plus we charge him a little honey for rent ; )
Newb
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