Pumpkin rotted

[Jonny.D]

Hi Guys,
I planted a Thai Kang Kob, took ages to produce flowers and I ended up with 2 fruits on it.

Everything was going well & then I noticed the one that was in amongst the foliage had rotted.

Can anyone shed any light as to why this happened? The fruit was on a piece of wood and was not in contact with the ground.

The other fruit is fine.

[ameno]

It didn't look overly large, so I would insufficient pollination.
Sometimes fruit will seem to have pollinated, and start swelling, only to abort when they reach 4-5 inches across. Water stress can also sometimes cause this to happen.
If anything else had caused it to rot then you wouldn't be seeing even all over rotting like that. It would be worse in one place, where the rot started, and then it would have spread across the rest.

[yogz]

It didn't look overly large, so I would insufficient pollination.

I have noticed this a lot with my courgettes and squash. I get really excited when I see the fruits start to swell, only to get disheartened when they stop growing after reaching a certain size. I have been hand pollinating everything to ensure pollination takes place. Anything we can do to ensure proper pollination?

[Jonny.D]

It didn't look overly large, so I would insufficient pollination.
.

Around 10" in diameter, so wasn't insufficient pollination

Water stress can also sometimes cause this to happen.

Something like the recent sustained downpour?

[ameno]

I have noticed this a lot with my courgettes and squash. I get really excited when I see the fruits start to swell, only to get disheartened when they stop growing after reaching a certain size. I have been hand pollinating everything to ensure pollination takes place. Anything we can do to ensure proper pollination?

Always use pollen from a male flower that opened that day, as the pollen starts to die after one day.
Always pollinate the female flower on the day it opened, as it becomes much less receptive on subsequent days.
If the pollen or the stigma of the female flower is wet, just forget it; wet flowers won't pollinate. If rain is predicted, you can tie off flower buds that are due to open the next day (you should be able to tell by their size and the fact that they petal colour is showing) in order to try and keep the rain out.
Be sure to rub the pollen on as much of the stigma as you can. Each seed requires a separate grain of pollen in order to fertilise it, and a certain minimum number of seeds need to be fertilised (although not all of them) in order for the fruit to grow to maturity.
Make sure the male flower actually has plenty of pollen on it. If it has, it should be very obvious. I find bees often take all of the pollen from squash flowers quite quickly (and yet still fail to pollinate the female flowers, rather annoyingly). Tying off a male flower the day before can be useful, if you find they often have no pollen by the time you get to them.

And sometimes, the flowers just don't set fruit. Perhaps the pollen was infertile for some reason, perhaps the plant was under stress, or perhaps the plant already had too many fruits, and so took to aborting any subsequent ones.

Around 10" in diameter, so wasn't insufficient pollination

Something like the recent sustained downpour?

Huh. That is pretty large.
Usually it's lack of water that is the problem, not too much. I feel it;'s unlikely to be that.
Have you checked the underside of the squash for damage? If a slug or insect damaged it then rot can easily get it.

[yogz]

Christ that's a lot of work :O( How do professional growers manage to grow anything? The way gardeners complain about having too many courgettes they don't know what to do with them! I managed to get 4 courgettes off my one plant this year. I doubt I will get more as weather is turning cold and all the little female flowers are turning yellow and rotting before being able to flower :O(

[ameno]

Christ that's a lot of work :O( How do professional growers manage to grow anything? The way gardeners complain about having too many courgettes they don't know what to do with them! I managed to get 4 courgettes off my one plant this year. I doubt I will get more as weather is turning cold and all the little female flowers are turning yellow and rotting before being able to flower :O(

It's a lot less work than it looks. It's really more of a list of what not to do, after all.

[Plot70]

You need to keep some flowers near by all through the season to keep wild bees on side.
I saved some comfrey and dahlias that were already on the plot when I took it on.
Wild bees nested under my tool shed and did all the pollination for me.

[ameno]

You need to keep some flowers near by all through the season to keep wild bees on side.
I saved some comfrey and dahlias that were already on the plot when I took it on.
Wild bees nested under my tool shed and did all the pollination for me.

It might vary by area or bee habits, but I've never found bees a reliable pollinator of squashes (or courgettes).
My squashes always attract tons of bees. I see dozens of them buzzing around the flowers. Yet left to their own device, I would be lucky to get a handful of fruits.
I suspect either the bees are only visiting the male flowers, and missing the females (the females have no pollen, after all, which bees also want, and the females also have shorter stems to are often hidden under leaves), or else the honey bees are too slim to pollinate such large flowers, and they slip in between the stigma and petals when the access the nectar, and never actually rub off enough pollen on the stigma.

[Plot70]

The bees that nested under my shed are white tailed bumble bees and are easily big enough for squash flowers especially once the 3/4 inch long queens start flying. The queens have been flying for a month now.
My squash vines have been setting about a third of there flowers. Basically they need a certain number of leaves to support each fruit and will carry on setting fruit and as soon as there are more leaves one will not abort and so on as long as there is sun and warmth.

[ameno]

Huh. I've never seen much in the way of bumblebees on my squash flowers. I have plenty about - the lavender is covered in them, and they like the bean flowers, too - but it's only ever masses of honeybees which visit my squashes.

[Plot70]

Perhaps you don't have the right species where you are.
The ones on my plot are a nesting species.
The ones that live on there own only need pollen.

[jdlondon]

I have had two patty pan squash on two separate plants, in separate areas, rot at just a couple inches. Very disheartening.

I thought you had to cut some leaves off to get air circulation and pollinators to the flowers - but maybe I cut too many leaves?

One looked slightly nibbled before it rotted so it might have been slugs, but the other looked nice and whole before it got squishy.

There has been a lot of rain and sun, and blight on the tomatoes and mildew on the peas, and earlier, some awful orangey speckling, like rust maybe, all over the broad beans which cut their lives short - so weather could so easily be the reason yet again.

I'm in desperate need for a polytunnel.

[TrixC]

Sometimes I find that squash plants only want to mature a single fruit, particularly the larger varieties. Often several fruits will start to swell and then the others abort and rot the way you describe.

[TrixC]

Huh. I've never seen much in the way of bumblebees on my squash flowers. I have plenty about - the lavender is covered in them, and they like the bean flowers, too - but it's only ever masses of honeybees which visit my squashes.

My courgettes and squashes always attract loads of bumblebees too - and I always seem to get good pollination. I’m not sure I’ve really seen honeybees taking an interest.