The skin on Jupiter is awful for my taste. But my buddy likes them. For hardy seedless I prefer Canadice, Glenora, or Reliance as far as eating quality. But don't know how they compare on disease resistance.

The University of Wisconsin has had a seedless table grape trial in Madison, WI (zone 5a) for several years now. Jupiter isn't part of it (though, they may have planted it now, and will collect data soon). The purple grapes they have are Mars, Trollhaugen, and Venus. All are susceptible to downy and powdery mildews in humid weather, and occasionally require spraying. They use organic sprays. It isn't as humid here as the East Coast area.

Here is their results:

Here is a link that might be useful: UW Seedless Grape Trial

I planted Jupiter, Hope, and Joy last year. All were developed by U of Arkansas, Hope and Joy in 2012. I didn't spray at all and Hope and Joy had no disease issues. Jupiter got mildew and maybe black rot which slowed its growth. The Hope vine right next to it got nothing. Hope and Joy both grew 10 - 12 feet. I can't comment on the taste as I didn't let any fruit ripen. However, it looks like the newest U of A varieties are very disease resistant, and I assume that includes the other two that I haven't tried yet - Faith and Gratitude.

These vines are all available at Double A vineyards, which I highly recommend for all grape vines.

Here is a link that might be useful: U of A grapes

Rob, thats good to hear Re: the new Arkanses grapes. I did one spray of myclobutanil at about 1' shoot length and had no problems on Hope, Joy or Gratitude. I also do a copper dormant spray.

Jupiter also did fine, and generally it does fine every year with that regimen. I like the taste of Jupiter but its got a bit too much of that slipskin skin on it. Swenson Red is thin skinned and crunchy like your grocery store grapes but it has seeds in it. Heres to hoping the new AK grapes come through on all counts.

Scott

Swenson Red is a very fine tasteing grape and quite hardy to boot. I have been growing it for some time now and it does quite well in this zone 5. It does take a beating and gets winter killed back quite a bit. It however can bounce back quite fast since it is quite vigorus and then produce a nice crop. If we can get a little break from the fall frost it will develop some nice sweetness. The seeds slurp down quite nicely and are good for you! I might also add that it gets very little care.

Scott, I'd like to hear about the flavor of your grapes once you get fruit. I'd like to add Faith and Gratitude, I just don't want to build another trellis!

There was a Geneva New York muscat seedless grape that never got named. NY 65.483.2
I think it has a richer more fruity muscat flavor, but the berries are not as impressive as Jupiter.
I like it better for my region and it gets sweeter and tastier.
Of course the Seattle Tacoma area is much cooler.

I personally regard Jupiter as one of the most delicious table grapes I have ever eaten, very sweet and with a rich, complex flavor. It is an interspecies hybrid, vinifera x labrusca. In my semi-arid climate it is completely bullet proof as to disease. I never spray my grapes at all. Very likely you could not get away with that in a humid area. I have also read that it is very cold resistant, another quality I do not need as our winters are mild. I just grow it for the incredible taste.

My other grape is a seeded table grape, Steuben. It is even more disease resistant and cold tolerant than Jupiter. I find it almost as good in flavor, and superior in that it produces over a longer period of time in my garden. Seedless grapes are wonderful, but I don't mind the seeded ones. After all, aren't grapeseeds supposed to be very nutritious?

Over in the tropical fruit section, there were two members who remarked that Jupiter grapes have a similar taste to Lychees, that they have a very floral aroma, very different from the regular grapes sold at the supermarket. I've never tasted Jupiter, but I just thought that was very notable since I'm a Lychee fan, but not really all that much into grapes.

If you like lychees you will love jupiter grapes, they are close in flavor.

I planted a 'Jupiter' vine seven years ago, and for the first time the vine is beginning to produce a bunch of grapes.

Mostly no big disease issues, but I'm in the PNW, so the summers mostly tend to be dry with clear skies. Some of the leaves do have signs of grape mite (bumpy leaf disfiguration), but not too bad.

The vine seems moderately vigorous, and they're in a more shady spot that only gets sun for a few hours in the day.