Too early to call at two inches. I don't know of any parthenocarpic butternut varieties but that also is possible.

Yes, I agree about two inches probably being a bit early to call. Need to watch them.

But it seems that there has been some success with breeding parthenocarpic (useful word, thanks) squash many years ago.

http://cuke.hort.ncsu.edu/cgc/cgc02/cgc2-19.html

You could have missed a few squash bees or other native bees that emerged from the soil under the row covers. They often make their galleries in soil near where cucurbits grew the year before, often deep enough to escape cultivation. When the next flowers open, go out first thing in the morning and see who is sleeping inside the blossoms. Male squash bees often do that to be sure of meeting ladies first thing in the morning.

OK, here's the situation a week later. These five butternut squashes in two plants are rapidly increasing in size. So this is under tulle, with no hand pollination. In fact, I'm pretty sure there were no male flowers (which was my original complaint).

So even if I missed a male flower (unlikely, this is a 6x3 foot area), who's doing the pollination? They're doing a very good job. Almost all the female flowers now have fruit on them.

It's hard to believe that wind is that efficient. Squash bees undercover? Perhaps, but I've never seen any in there, and the job is a lot harder if there are no male flowers. I'll keep my eyes open.

These plants were just selected off-the-rack at a local nursery. The ID tag that came with them is buried under some layered compost, so it may be a while until I can excavate that.

I'm wondering if I should be prepared to collect seeds from this patch!

Maybe ants or another crawler assisted?

I actually just had something very similar happen.. I had 2 summer squash plants that put out all male flowers, then all female flowers, one got killed by wind damage leaving only the one with only female flowers, few days later, I noticed that one of the 'fruits' wasn't rotting away like the others, it's been a couple weeks now and it's just growing in size.. It's about half the size of what you'd buy in the store and still growing.

I have to wonder that, if you had male flowers at one time, then there perhaps was some pollen laying around on the ground for when the female flower appears? But that's interesting. Makes one wonder, how long does the male pollen last? That is, if you have a male flower, can you pick it for "insurance" for when the female flowers come out later?

Pollen isn't viable that long.

Well, if you didn't have pollen, then there likely won't be any seed to save. :)

I think that's correct about pollen viability. I did a little digging, and established that in at least one research project, squash pollen is 95% viable when the male flower first opens, and 72% viable when it closes later that day, By the next day, the viability is 10% or so. So it seems unlikely that pollen can just get dumped on the ground and used later.

So much for that idea.

Tried to post this earlier and I thought I did.. Didn't go through I guess.. Anyways..

Was out taking pics of the garden today, figured I'd take a couple of the squash and post if anyone was interested. It was originally all white, it's only started taking on color the last few days. Growth has slowed on it though.

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My "virgin birth" squash are getting bigger and bigger. Now that those fruit are well along, I'm getting lots of male flowers. But no more female flowers, so as my patch is under tulle, I've never gotten to do any manual pollination.

Looking into these male flowers, I occasionally see an ant or two. Hard to believe that they did the job, especially in that they'd have to crawl a block or two away to find a male flower.

Parthenocarpathia, methinks.

It seems that there are at least varieties of commercial zucchini (Cavili) and even cukes (Carmen) that have this property. The latter aren't cheap! One would think that such varieties would be extremely well suited to being under netting to protect from SVBs.

I am surprised that no one here pointed out that Butternuts are Curcubita Moschatas which are not typically attacked by borers. I grew only that kind last year and not a single plant was affected. No covering needed. Just a note.

Very interesting thread though.

I am growing yellow crooknecks under row covers this year for the same reason and with the same plan.

Actually, that's not true that these are not attacked by SVBs. These squash are "resistant", but they aren't immune. Other squash, and cukes, are "highly susceptible". I lost a few stems in a crop last year to what were clearly SVBs, which is why I'm putting them under tulle now. Maybe my SVBs just work harder than most! My goal is to beat the borers, and when I've learned how to do it with these, I'll try the more susceptible ones.

Wow. That's not good news. Sorry for the inaccurate information. Hope the tulle works.

Donna, I'll be interested to hear how you do with your yellow crooknecks under covers. Once I get some confidence with these butternuts, I'll probably try those. I'm interested in vining squash, as the more vertical ones like zucchini won't fit well under tulle, unless I splice some pieces together. I'm too cheap to get large area row covers ...

OK, back again. Just gets weirder and weirder. I now have two very healthy butternut squash plants (each vine is about six or seven feet long), pretty well sealed under tulle. As I wrote earlier, I had female flowers with no (that I could find) male flowers, and ended up with several squash. I now have SIX beautiful squash, and I have NEVER done any hand pollination. Never ever. My plants switched over to producing mostly male flowers, and an occasional female flower. Those one or two female flowers immediately started fruiting, but I have to say that I never saw male and female flowers open at the same time.

So I have to assume at least wind pollination (or perhaps some very creative insects), but probably also parthenogenesis.

Now, what's a little unusual is that my squash don't quite look the way they usually look. The biggest ones (most of them, actually) are six inches long by three inches in diameter. A bit on the small side, and not growing quickly anymore. They are mostly not funnel shaped, as butternut squash usually are, but more cylindrical. They are also completely tan. They look ripe. Now, in previous years, I'd get larger (eight or nine inch) funnel shaped squash that were white/green striped that didn't turn tan until midsummer. These guys are only white/green striped for a few weeks when very small.

So I suspect that (1) I have a different variety of squash than I usually have. Um, in previous years I sometimes just used volunteers from my compost pit! But perhaps (2) that parthenocarpathia is producing somewhat unusual fruit.

Mysteriouser and mysteriouser. This is my first year using tulle, and I'm just boggled. Any experts in parthenogenesis out there??? Google is my friend, sort of. There is a 1914 reference on parthenogenesis in butternuts but (after I got excited) I realized they were talking about trees.

Have you sliced one open to see if there are any seeds yet? That will help decide pollination vs parthenogenesis.

I'm not sure what seeds has to do with deciding this. I think this phenomenon (see also apomixis) is one that results in a fruit, with seeds, but that are genetically identical to the parent.

It would be pretty interesting to collect the seeds, and see if I've stumbled upon a variety that just likes to do this. But no, I have not harvested any of the squash.

I thought the definition of parthenocarpy was the development of fruit without fertilization or formation of seeds.

Sunnibel - You're right! I didn't know about partheno-whatever and seedlessness. I'm reluctant to pull off the squash before they're really full sized, but when I do, I'll certainly be looking for seeds. If there aren't any, that will make it hard to raise such a handy variety again, I guess. Thanks, and standby.

It surely does make seed saving hard :) I guess that's why seedless watermelon seeds are so expensive? I'm not sure how they get those,a cross of certain parents? Raditation?

It could be ants. I usually have a lot of ants in my squash flowers. This year I am trying Romanesco Squash and I put them out late. I removed all the male flowers that I saw because I wanted the plant to get larger first. I didn't have any female flowers at that time. Then about a week later, I saw a female flower with fruit, but I still had no male flowers. There were a lot of ants in the female flower. Low and behold, I have a zucchini! With no male flowers. I think ants are small enough to get through tulle.

OK, I have an answer. My butternut squash plants have continued to thrive, but the squashes topped out in size about 4-inches long, and 3-inches in diameter. They didn't get any bigger. Barrel-shaped -- not the usual shape for a butternut squash. When they were very small, they were green with stripes, but very quickly turned all tan. That too is unusual. Previous butternuts I've grown take months to get tan, as they continue to increase in size.

One became badly cracked, and another was threatening to do so, so I pulled them off. I dissected the cracked one.

And the answer is .... drum roll ... NO SEEDS! Not even a seed cavity. Solid meat. I didn't taste any, but it smelled nice, and as expected, and had a rich orange color. I'll eat some of the other ones in a day or two.

So I think what I've been witnessing is true parthenocarpy, as I never once did any hand pollination, and the tulle prevented any classical pollinators from entering. In fact, the first four fruit were produced before there were male flowers. So we're not talking wind or ants. (The closest neighbor with a vegetable garden is one or two hundred yards away.)

So I think the lesson is that partheocarpy can happen in butternut, but the squash you get are a bit unusual. They have no seeds, mature quickly, and are a bit on the small side. I guess I have no options for preserving this variety.

I have no idea what makes butternut squash plants want to do this. These two plants were very happy about doing it, and produced half a dozen squash, so far, in this way.

Again, the plant identification tags that came with them is buried under compost. I'll excavate them later. I don't recall them being labelled as any bizarre variety.

Just an update. My plants keep producing all by themselves. See the picture, which is where we cooked up three of them. There are quarters on the slices for scale. As you can see, these are pretty small butternuts, and unusually cylindrical. No tapering in the shape. This picture is after slicing them in half, but before they were cooked. Nothing was scooped out of the slices. As you can see, almost no seed cavity, and no seeds. None at all. The outer flesh is normal butternut tan which, unfortunately, you can't see in this picture.

The flavor was quite nice. Nothing strange.

They look a bit like the mini butternut, the Honeynut, just without seeds. They too don't have much tapering. How interesting!

They do indeed look like Honeynut on the outside. I suppose the nursery could have gotten in a bunch of those, and sold them as regular butternut (my apologies, but I still haven't managed to excavate the tag, which I stuck in the ground next to them). If so, then we're looking at parthenocarpic Honeynut, without seeds.

I have had Sucrine Du Berry and Waltham Butternut both do this to me. I had female blooms when for sure there were no male blossoms within a half mile, and probably much longer. I got no seeds. The Butternuts were the awesome. The seed cavity was virtually non-existent. They were delicious and provided a huge amount of food. I'm thinking maybe I should pull off the male blossoms, but I doubt I would have the nerve.

That sounds like exactly the same thing that is happening to mine! Were your fruit also on the small side?

Canby, eh? I was just up thereabouts in Molalla!

Just a quick follow-up report. A month ago I took the tulle netting off to see what would happen. Today I just harvested two normal-looking, full-sized butternut squashes that got started after the tulle came off. So I think the lesson here is that for this particular variety at least, if you allow normal fertilization, you'll get normal fruit. If you don't, the plant will go parthenocarpahtic, and try its best to do something, fruit-wise.

I have not yet cut open the new squash, but I suspect they'll be full of seeds.