The only parthenocarpic summer squash that I am aware of are zucchini and dark green zucchini at that. The development of partheno carpic hybrids is patented, so it seems to be restricted to high volume types. Varieties at present include Sure Thing, Partenon, Cavili, Whitaker.

I haven't found a parthenocarpic yellow squash. I'm going to try Perfect Pick parthenocarpic zucchini from Jung Seeds in an attempt to evade the SVBs.

Thank you. Yes the SVB is a real menace that I too would like to evade!

Cavili is in this month's Organic Gardening as one of the 10 best from their trial garden.

The link has one rater that likes it.

Here is a link that might be useful: VVG rating

@farmerdill When does the patent on developing parthenocarpic varieties expire? Does the patent only apply to zucchini, or to all plants? When was the patent granted?

I don't think the process is patented. All the varieties that I am aware of are hybrids and the protection is provided the developer by trade secret. That is to say they don't publicize their breeding lines. Most were developed for the greenhouse trade. Cucumber, tomatoes are also available. The H-19 cucumber is both open pollinated and parthenocarpic. Some varieties have a natural tendency toward being parthenocarpic and these enhanced bu selecting breeding. There is a lot of research particularly in China and India to use genetic modification, but nothing on the US market as yet, https://books.google.com/books?id=ygolH97ENLcC&pg=PA205&lpg=PA205&dq=Breeding+parthenocarpic+vegetable+seeds&source=bl&ots=g0dqKphh9r&sig=zZ12lNH3tTnfrLsK7G0443cXCmw&hl=en&sa=X&ved=0CE0Q6AEwB2oVChMIleaLhvjuxwIVDHU-Ch16TQf0#v=onepage&q=Breeding%20parthenocarpic%20vegetable%20seeds&f=false

A number of squash varieties have some level of parthenocarpic capability. See

http://www.hort.cornell.edu/expo/proceedings/2014/Vine%20crops/Seedless%20squash%20Reiners.pdf

Looks like Golden Glory is something worth trying. Seeds are marketed by many providers.

Golden Glory is a yellow zucchini from Syngenta. It is not listed as a parthenocarpic variety however. Johnny's is a reliable vendor that also makes no parthenocarpic statement. A parthenocarpic yellow zucchini shoul be possible.

It may be that no one had realized that GG was parthenocarpic. But this experiment seems to prove that it is.

I'm guessing that when Johnny's posts a statement suggesting they may be parthenocapic, the price will rise significantly. Get 'em before they figure it out!

I found this potentially lapsed patent: https://www.google.com/patents/US6031158

I grew both last two years - Perfect pick and Cavali under cover. May be it' me, but more then half of the fruit ended up rotten or misshaped young. This year I had to take the cover off due to some other issue, and production became much better, until they died due to SVB. I also planted tromboncino this year, and I think this is what I am going to do from now on. It survives SVB, cucumber beetles, groundhog, and powdery mildew. It has its damage, but keeps to grow and producing. I grow it vertically, so it doesn't take more space, same as zucchini would. The taste is different, but i like it. It is less watery, and has no seeds other then very top of it, that you can just cut off. Next year they go on the wider bed with trellis then this year, so I am planning to plant three plants on trellis, and 3-4 regular zucchini in front of them and keep them under cover until they start flowering or over grow cover height. After that I will enjoy about a month of regular zucchini, until tromboncino started to produce, the SVB will take the zucchini, and tromboncino will have whole bed to enjoy)

Easypick Gold is a very good parthenocarpic yellow squash. It is available from Territorial Seed Company.