Hand Pollinaton of Squash

[macmex]

Hand pollination is a way to:


1) Assure pollination of squash (or other cucurbits). If all you want, is to be sure you get fruit, while in an environment in which there are few pollinators, then you can skip all the tape and just simply use the respective flower parts, pollinating in the morning. This will get you fruit when there are no pollinators available.

2) Produce pure seed in an environment in which there are (or may be) other squash of the same species, which could cross with your desired variety. See the thread titled "On Maintaining Purity of Squash Varieties" for a basic explanation of the different species of squash (and, or course pumpkins). There you can get a start on identifying what species of squash you're working with.

In order to produce pure seed using hand pollination, you need to have access to your squash plant, while it is flowering and producing fruit, and at two times of the day:

1) After 2:30 PM in the afternoon. This is when you select flowers which are going to open the following morning, and, when you seal them, to protect from foreign pollen.

2) Between sunrise and noon, the following day. This is when you do the actual pollination.


Note: If ever you believe you had a lapse in procedure which could affect purity, mark the fruit and DON'T TRUST IT to be pure.


Note: Squash cross MUCH MUCH MUCH more easily than you probably think! To be absolutely sure to save pure seed without hand pollination, a variety needs about a mile of isolation from other varieties of the same species! Somewhat less distance may at times work. But one never knows.


So, let's take a look at the process. For practical purposes we'll focus on the production of pure seed.

[macmex]

First off, it's important to understand that squash have what is known as incomplete flowers. This means that no single squash flower contains everything necessary for the production of seed. There are male flowers, with male parts and pollen. There are female flowers with female parts to receive the pollen. Just for kicks, you can know that the male part, which produces pollen is called the stamen. The female part, which receives the pollen is called the pistil. But you don't need to know these terms to be successful in hand pollination. "Male part" and "female part" will suffice. 

The male flowers tend to be more slender than the female. The female flowers generally have a little tiny squash beneath them, where they join to the stem of the plant. 


Here's a picture of both a male (left) and female flower (right), which have just been sealed with masking tape, in order to preserve its pollen for the coming day. (Note: Wide masking tape is much easier to use than narrow.)



Here's a picture of a female flower which ready to be sealed with masking tape.



Notice the little squash at the bottom end of the female squash flower.
Also notice that there is an untaped male flower just to the left of the middle flower, which is a female ready for taping.
The flower on the right is a female flower. But it lacks another day to color up. One ought not to tape a flower shut until the afternoon before it will open. If taped shut prematurely, and left taped shut, it will abort.

[macmex]

Also, keep in mind, that the degree that a flower colors up, the day before flowering, differs from one variety to the next. So, it really helps to get to know your variety, in order to more easily know when to tape flowers and when to let them alone. 

Here's a picture of that same female flower, now taped and ready for hand pollination, the following morning.




Notice I taped a male flower, for use as well. It does not hurt to "self" squash. "Selfing" means to use pollen from the same plant as is applied to the female blossom. This may reduce some of the genetic diversity, if repeatedly performed. But the resulting seed will produce squash plants that will be very vigorous and healthy.

[macmex]

Here's how you do it.


1) Have wide masking tape on hand. You might even rip off about 4 -5 inches and stick the piece to the back of your hand, for safe keeping. Be aware, that if there are honey bees around, they may try to dive into one of your flowers, effectively negating all your effort to preserve purity. So, keep a weathered eye open for bees!
2) Pick the male flower with a little bit of stem on it.
3) If they are not right next to one another, take the male flower over to the female flower. There you can rip the petals off of the male flower. This will leave you with a little natural "pollen paintbrush." I often find a little handy shelf to lay this on, using an open squash leaf.
4) Grasp the tape on the female flower and try to remove it without completely removing the petals. Sometimes you just have to tear off the end of the petals, with the tape. Once free from the tape, a mature flower will immediately open.
5) Use the male flower (minus petals) to brush pollen onto the pistil of the female flower. If the male flower is indeed mature, you will see the yellow powder come off the stamen and stick to the pistil in the female flower.
6) Grasp the petals of the female flower and gather them back together, closing them. Then use the masking tape to seal the flower shut. If there is any doubt about how insect proof the petals are, use another piece of masking tape to augment the seal.
7) Try to avoid taping the actual  fruit below the flower. This may cause it to abort.

Here's a picture of a stamen, ready to use, resting on a squash leaf. The leaf makes a handy "shelf" while I'm preparing the female flower.



Here's a picture of a female flower being sealed up again, after having been hand pollinated.

[macmex]

For several days the tape will remain as a marker, showing which flower has been hand pollinated. But within three days, not only will I know if the flower is going to go on to maturity, but also, I can mark the little squash, so at harvest I know that this is the fruit, from which I need to save seed! The tip of a ball point pen or even an old nail is sufficient for marking the little squash. All you do is scratch a symbol into the skin of the young fruit. That symbol will grow with the fruit.

Here's a picture of a young hand pollinated squash which has just begun to grow. Notice that the tape is starting to get loose.


This is when one ought to mark the young fruit.


Here's a picture of a squash which was marked and which has grown considerably:


Since the time of this picture I have take to simply marking my hand pollinated fruit with a "P." "P" is for "pure." It's faster and less damage to the immature squash. So, theoretically, the little fruit will be less likely to abort.

A certain number of female squash blossoms do abort. So if your hand pollination aborts, just try again. It may have had nothing to do with your technique.

[macmex]

Hand pollination allows a gardener to reliably reproduce seed of their favorite squash/pumpkin. It can also be a tool for breeding squash varieties. I first worked with a variety which had many shapes. Over the course of about 15 years, without thinking about it, I selected flowers from just one of those shapes, which I liked the most. Suddenly, one year, I woke up realizing that I only had squash with that one shape! I had selected a new variety!


Hand pollination makes it is easy to do controlled crosses. Just keep in mind that, after the first (F1 hybrid) generation, the plants will differentiate a whole lot. It may take a decade or more to stabilize that cross into another stable variety.

[john]

George that is a great tutorial, I wish I had seen it earlier as it would have been perfect to use for a class I am teaching on growing giant pumpkins. Just about all giant pumpkin growers do hand pollination on their plants and the 'Atlantic Giant' variety has improved so much in the past fifteen years because of it. When I started back in 2006 the world record was 1468 pounds, Now the world record is 2,624 pounds! Imagine if everyone was a plant breeder, we would have no need to buy hybrid seeds from Monsanto or Syngenta. Everything we need is already in the seed, we just have to find the genes we want and select for them. It baffles me to think that for thousands of years the Cucurbita maxima has had the genetic potential to grow a 2624 pound fruit. The C. maxima also grows the tiny little butternut squash! What a difference! The genetic diversity is amazing.

Thanks for taking the time to do this.

[macmex]

Thanks John. It was quite a bit of work. However, the information was worth gold to me when I needed it.
You know, I believe, to date,  they have not developed anything in plants using genetic modification techniques which could not be done with old fashioned plant breeding. The fact that the weeds are keeping pace with them is testimony to that!


When I was in my 20s the best breeding being done for home gardeners was basically overflow from university work. Now, it's hobbyists and small private seed companies. The "big boys" left most plant breeding to chase after bio-engineering.

[john]

That is a good point about the weeds keeping up with all that technology can throw at them. I had never thought about it that way.
The best slicing cucumber in my opinion is still the open pollinated 'Marketmore 76', it resists disease better than any other variety and it will outyield others too. It was developed by Cornell. My favorite open pollinated slicing cucumber is the 'Little Leaf'developed by the University of Arkansas. The 'Marketmore 76 and the 'Little Leaf' are wonderful gifts to the world. It is too bad our Universities and private institutions don't really put much effort into breeding these great open pollinated types. It would have taken time but land grant Colleges have been around for over 100 years. Think of all the wonderful open pollinated varieties we could have by now if we had maintained a focus on open pollinated seeds. Maybe we would even have an open pollinated sweet corn that tastes as good as a modern hybrid.

[macmex]

It's hard to imagine what might have been accomplished. I'd like to work with Green Country Seed Savers to educate and produce more gardeners who are versed in seed saving and even selection. Ron Cook, himself, is a great asset to the group, with his experience and practice, developing Heavy Hitter Okra.

Yet, there are opportunities galore for development of new vegetable varieties.
Here's a link for a great book about doing this: Breed Your Own Vegetable Varieties: The Gardener's and Farmer's Guide to Plant Breeding and Seed Saving, 2nd ed.

by Carol Deppe

caroldeppe.com/byovv.html