White Out is being marketed as part of the "Knock Out Family", and it was hybridized by Bill Radler, who hybridized Knock Out. The small number of reports that I have received so far is that the disease resistance is suspect, and that it fades quickly.

The light pink was probably Blushing Knock Out, which is a color sport (mutation) of the original Knock Out. I have it, I love it. Totally disease resistant for me, with good rebloom, and a light fragrance. I think Knock Out is mildly fragrant too.

Thanks for the information, Diane. I am actually interested in getting a couple of knock out roses for my daughter's flower bed. She is very, very busy (1 child in little league and 1 in gymnastics)and has no time for "fussy" plants, but she loves roses. Will all of the knockout roses grow to about the same size? Can they be easily maintained at about 4x4. I have more than 75 roses, but mine are all teas, chinas, hybrid musks,and noisettes and have zero experience with the knockouts.
Molly

I think that KOs will be much bigger than 4x 4 in zone 9 and are very thorny. How about some polyanthas? Perle d'Or is much more attractive. Or, Clotilde Soupert that is also very fragrant.

In your area I'm guessing Knock Out and Pink Knock Out get pretty big. Rainbow Knock Out, on the other hand, is clearly a smaller plant in most areas, as is Double Knock out. I think you would easily be able to maintain them at 4x4 without much problem.

I love the Sunny Knockout. It starts yellow, ends up large white flowers. I have had 2 people comment mine look like gardenias. The color goes well with other annuals - I am really liking this rose. I havent seen much of White Out, but I think Sunny Knockout is better.

I absolutely love White Out. The bush grew beautifully for us last season. There was no blackspot at all, it was always in bloom and it grew into a nicely shaped mound very quickly. It was beautiful. The foliage was a nice dark green which contrasted nicely with the pure white & the nice growth was that nice burgundy color which was beautiful against the green & white. This is not officially a Knock Out, but it is my favorite of the group.

White Out has been a fantastic shrub rose for me. Dark dark foliage, continuous white/cream colored blooms, self cleaning, requires no pruning, was the only rose that thrived during my rose slug infestation last year. No scent but otherwise an amazing compact landscape rose.

Thanks to dollsandroses and srgraves for the comments, but information about disease resistance is much more helpful if you say approximately where you live.

I'm in New England where we get major blackspot & this bush was healthy & clean throughout the season.

I have two Sunny Knock Outs. They are quite a bit smaller than the other Knock Outs. The yellow fades to a dirty white and doesn't stand out in the garden. Personally, I think the reds and pinks are prettier.

I'm located in San Diego, CA.

Thanks to all for your input. Comments regarding roses that I consider buying is so very helpful, even when there are different experiences with the same rose. I purchased Thomas Affleck roses for my daughter's garden since this area is along the sidewalk leading to the front door and the lack of thorns is a big plus. However, I am smitten by the White Out and plan to purchase one to plant in my moon garden.
molly

This is great information about the White Out. I am also in ATX and planning on White Out. How are yours doing @jardineratx?

Cyndi, I never got around to purchasing a White Out rose. By the time I researched this rose, they no longer had it at the nursery, lol

Molly

When I first got my White Out many years ago it was introduced as a knockout. They dropped it as a knockout the following year. My White Outs are disease free. I love them. They are always in bloom for me and grow to about 3'x3' every year.

End of last season after several frosts

One of the new ones this year