Identifying interspecific squash seedlings

[Mike Deyo]

Update on the squash I started in December to try to see if I could tell if they were successful interspecific crosses. I ended up discarding the pepo X argyrosperma plant, as it exactly resembled the pepo plants. I will try more seeds from that cross this spring, just in case there are a few obvious hybrids. I kept the argyrosperma X moschata plant, and the moschata plant, transplanting them into larger pots under led plant lights indoors. My thought is I will try to backcross with pollen from the moschata plant. In an attempt to encourage earlier production of a female flower in the arg X mos plant, I pruned off any male flower buds, and most of the side shoots developing from leaf axils. I was pleased to see a female flower has developed! There are also male flower buds on the moschata plant. I will have to cross my fingers that the timing of blooming will work out to get a pollination.

In the first picture, the moschata plant is in foreground, and the arg X mos is in background. The latter is in a 18 inch pot. The second photo shows the female flower bud on the arg X mos plant.

This is all very experimental, I have no idea if I can mature a fruit in a 18 inch pot, when the parent plants had large vines when grown in garden.

[Mica Winnower]

I look forward to seeing what it ripens into. I'm always curious about potential leads that might improve my moschatas in the future.

[Mike Deyo]

I'm curious to see what it does too. Even if I don't succeed with a pollination growing under lights, I know I can try again growing outdoors this summer.

This present cross, I'm showing in the photos, is more about improving/changing argyrosperma, since argyrosperma is the female plant. On the moschata side of the cross, which is itself a cross: Burpee Butterbush X Ithanga, I will be planting ~20 or so F-2 seeds this spring, with the hope that I can pick out bush plants while they are seedlings. Then I will just grow out the bush plants, selfing them and hoping to get some of the fruit flesh quality of Ithanga in a bush moschata like Burpee Butterbush. I could use one of those bush plants as a male to back cross pollinate my interspecific cross (Tennesse Swt Pot X Mex Wild Green) X ( Burpee Butterbush X Ithana ). It would be neat if I could get the bush gene into the argyrosperma, as well as some fruit flesh quality from the moschatas.

Here in Ohio, argyrosperma is the most resistant to squash bugs. This past year they barely touched them. Moschatas can get a lot of squash bugs, but they don't seem to slow them down very much, especially if you lower the load by finding and crushing eggs. Pepos get a lot of squash bugs, and they can be weakened even by a small number of them. It's a race somethimes to get mature fruit. Even worse on the pepos are vine borers, which I haven't seen on moshatas or argyrosperma.

[Mica Winnower]

I do love those Ithanga you showed off, with those enormous sepals/calyxes(?) they had.

[Mike Deyo]

It looks like this female flower on the argyrosperma X moschata plant is about to bloom. Unfortunately, I don't have any male flowers ready to bloom. I included a photo of one of the male moschata flowers that is farthest along.

The female flower doesn't appear to have a butternut shape like the moschata pollen parent. I don't remember if the two argyro's that went into the cross had sepals like that, or whether that came from the Ithanga in the moschata half of the cross. You can see the big leafy sepals in the male moschata flower, although it's magnified by the camera a bit compared to the first photo.

I think this female flower developed quicker because it was close to and above a smaller plant light I am using for some dwarf tomato crosses below. The air is warmer there. Luckily there is another female flower on the ArgXMos that is in a cooler location and developing slower. Hopefully it will line up with some of the male moschata flowers so I can make a pollination.

[Mike Deyo]

The female flower opened on the possible argyrosperma X moschata cross. This would be a F-1 interspecific plant. Does anyone have experience with what the flowers would look like on a cross like this?

[Joseph Lofthouse]

Traits on F1 plants tend to be mid-way between the phenotype of the parents. The previous photo looks like a hybrid to me.

[Mica Winnower]

If I notice that I'm getting a female flower near blooming without any male flowers, I'll wrap the female flower with something to cover it from the sun and pests, and it typically gets me an extra day, which is usually enough time to get a male flower that might not be open, but should have some pollen.

But yeah. Getting a fruiting flower with no pollen source is one of the more frustrating things to deal with in squash breeding like this. Forces some emergency decision-making.

[Mike Deyo]

Traits on F1 plants tend to be mid-way between the phenotype of the parents. The previous photo looks like a hybrid to me.

Thanks, Joseph. That's good to hear. Even if I can't get a back cross done on this plant growing indoors, I know I can do it outside this summer. I will probably try both moschata and argyrosperma as male parents, since I don't know which might work best.

If I notice that I'm getting a female flower near blooming without any male flowers, I'll wrap the female flower with something to cover it from the sun and pests, and it typically gets me an extra day, which is usually enough time to get a male flower that might not be open, but should have some pollen.

Mica, your suggestion gave me an idea to try. I have 4 male flower buds on the moschata plant that have just been sitting there, not progressing to blooming. I'm going to try to accelerate their development. I chose two, wrapped aluminum foil around the base of the flower to reflect more light on them, and covered the top with plastic wrap to enclose it and maybe have a warmer environment around the flower. I never thought my problem would be a lack of male flowers, but that is how it has turned out. Another thing I have read about, is cutting a male flower that is opening in the morning, and storing it in the refrigerator in a ziploc bag for a few days max, to pollinate a later developing female flower. I will try that with any male flowers that bloom if I don't have a female flower ready.

[Mike Deyo]

I finally got a male moschata flower to bloom, actually two this morning. I also had two female flowers on the argyrosperma X moschata plant that opened yesterday morning. I taped them shut yesterday, in the hope they would stay fresh enough to take pollen this morning, one day after anthesis. I could tell by the appearance of the two male moschata flowers that they would open today. So, fresh pollen on one day old female flowers. I pollinated both arg X mos flowers, I'll just keep one. I hope the fruit will mature and I will be curious if it shows more evidence of a species cross.

The male flowers on the moschata had been present for more than two weeks, but seemed to have stalled in development. They had developed early, and close to the base of the plant. I had 4 female flowers grow from tiny buds to blooming during that time, but with nothing to pollinate them with I picked them off. I tried putting a heat mat under the male flowers, but it didn't speed up development that much. What finally seemed to work was some radical pruning of the moschata plant. I cut off all vine tips, some old leaves, and all small female flower buds. The first two male flowers opened about three days later.

To review, I have two squash plants growing indoors under lights that I started in December. One plant, the female in today's cross, is itself a cross between an argyrosperma and a moschata I made this summer. The parentage is a bit complex, as the argyrosperma was an F-1 plant of Mexican Wild Green Cushaw X Tennessee Sweet Potato, and the moschata was either Burpee Butterbush, or a F-1 plant of Burpee Butterbush X Ithanga. So the female in today's cross is (MexWildGrn X TnSwtPot) X ( BBB or BBB X Ithanga). The male in today's cross is an F-2 plant of Burpee Butterbush X Ithanga. An interspecific cross argyrosperma X moschata, that today I back crossed to moschata.

I don't know if I will have space to fully investigate this cross, but it will be interesting to see if the bush growth habit and good fruit quality from the moschata parents can be introduced into a pest resistant argyrosperma background. The Mexican Wild Green Cushaw is not helpful in this goal, as it is grown for eating the seeds only, probably poor fruit quality.

The first photo is of the two male moschata flowers that opened today, and the other two are the agyro X mosch that opened yesterday, and were pollinated today.

[Mike Deyo]

Update on the fruit developing on my F-1 argXmos plant. The pollen came from a moschata plant. So it is a backcross. The pollination was done on Feb.15. I had pollinated two female flowers that day. I pruned off the one that was developing slower, after a week. The fruit that I saved is developing unevenly, one side not swelling out as much. I'm guessing there are no seeds on that side. I'm planning to wait to pick it til ~60 days after pollination, which would be April 15. As long as the plant lives til then. I am hoping for seeds inside, and it will be interesting to see what the flesh is like.

Of the parents, Tennessee Sweet Potato had a white skin with a slight greenish tone, shape sort of pear like. Mexican Wild Green Cushaw had a flattened globe shape with white skin and green stripes/flecking. Ithanga had immature fruits that were mottled dark green and light green, that ripened to tan, a short neck butternut shape. Burpee Butterbush is a typical butternut shape and color. This fruit appears to have the shape of Mexican Wild Green Cushaw, with the color of the butternuts, although the tan color seems a bit lighter.

[Mike Deyo]

About 10 days ago I decided to harvest the crossed fruit. The plant's leaves were yellowing, and then getting brown edges. Any ideas as to what that might be? The leaves were yellowing well before they got old. The youngest leaves were still green, and the plant was still growing and blooming. I figured it wasn't contributing much to the fruit. I stored the fruit in a warm room for 10 days where I was starting tomatoes and peppers (~80F). Hopefully to help the seeds mature. When I rapped it, the fruit felt hard as a rock. Photo is of fruit just before I opened it today. It was 58 days since pollination. I used a hacksaw to circle around the rind, which was ~1/8 inch thick. This was surprising since none of the parents have that thick a rind. The flesh was not bitter (tasting raw), and appeared to have a smooth non-grainy texture. Most of the seeds were completely undeveloped. Luckily, there are 10 seeds which appear to be good. I will know for sure once they dry. It looks like the seeds have an enlarged edge, similar to the Mexican Wild Green Cushaw, but not the corky surface. They are much larger than the seeds of either of the moschatas in the lineage.

To review the plant's history, grown this winter under lights, it's seed came from a fruit on a F-1 plant this past summer (Mexican Wild Green Cushaw x Tennessee Sweet Potato), that was pollinated by Burpee Butterbush this past summer (or possibly a F-1 plant of Burpee Butterbush x Ithanga). That's argyrosperma x moschata. The seeds on the plate were pollinated this winter by a single F-2 plant of Burpee Butterbush x Ithanga, so a backcrossing to moschata. The pollen parent was grown under lights as well, and once I saw the pollination was successful, I got rid of it as there wasn't room to grow it to maturity as well.

I think I will try to grow one of the seeds this summer, and see if I can successfully self it. There should be a lot of variety in the F-2. I don't know if I have enough garden space to pursue this cross fully, but I will be interested if any bush plants like Burpee Butterbush emerge, in a at least partial argyrosperma background.

[Mike Deyo]

I was not able to germinate any seeds from the crossed fruit I grew indoors. There were only two seeds that were filled. They were not fully filled. After a week of no sign of germination, I peeled the seed coat off. There was an embryo inside, that had absorbed moisture, but no root. I tried the embryo for another week in peat moss, and there was no germination, it eventually rotted. So either the seed had not developed enough, or the second crossing with moschata led to an embryo that would have needed embryo rescue. I have planted three seeds in the garden from the argyroXmoschata fruit of last summer, I will try pollinating it with pollen from an argyrosperma- Papalote Ranch, and also try selfing.

The main interspecific cross I was interested in last summer, was argyrosperma x pepo, where the argyrosperma was one of the silver seeded varieties (large seeds), and the pepo was hulless. I would like to get the hulless trait into argyrosperma, as it is much less bothered by squash pests than the pepo. The first photo is of the potential species cross. The second is of the argyrosperma female parent, and the third is of the pollen source, my hulless pepo.

I'm pretty convinced it's a successful species cross, as the leaf outline of the crossed plant looks more like the pepo pollen parent. I will try backcrossing to a silver seed argyro, as well as selfing it.

[Mike Deyo]

I planted two plants of the possible argyrosperma X pepo cross out into my garden on May 10. They are growing vigorously, and had a number of female flowers develop, and then after a week a few male flowers. Since both parents were genetically diverse (the argyrosperma was a cross between Tennessee Sweet Potato and Mexican Wild Green, and the pepo was from an open pollinated population from crosses I did ~20 years ago, with naked "hulless" seeds), it's not surprising the fruits of the two plants look different. It's interesting that both have an elongated shape, which none of the parents did. On the argyrosperma side, Mexican Wild Green was a flattened round shape and Tennessee Sweet Potato is pear shaped, has a short neck. On the pepo side they are pumpkin shaped, of varying sizes. The north plant fruit has the coloring of Tennessee Sweet Potato, while the south plant coloring looks more like my hulless pepos, and more like Mexican Wild Green. I'll put in photos of two hulless pepo fruits so you can see the variation and similarity.

The argyroXpepoNorth fruit came from the first flower to develop, and was pollinated with pepo pollen from 5 different plants. The south plant fruit came from a later flower, and there were male argryoXpepo flowers available. I tried something different for it's pollination. You know how there are three lobes of seeds in the mature squash fruit. There are three lobes on the stigma in the female squash flower. I put pollen from the north argyroXpepo on one lobe, from the south argyroXpepo (selfing) on the second lobe, and hulless pepo pollen on the third lobe. My thought is the diverse pollen might help ensure the fruit develops, but I might also be able to to tell which lobe is from which cross in the final fruit. I would expect the lobe with the hulless pepo pollen would be more likely to have some hulless seeds, or if vice versa the pepo pollen doesn't produce filled seeds there will be a lobe with no good seeds.

I'm waiting now for my straight argyrosperma plants to have male flowers so I could try backcrossing that way too.

[Tim DH]

An interesting idea, to pollinate the three lobes of the stigma with different pollen, I'll be interested to hear how that goes.

Tim DH