closer:

This part looks healthy...

Based on this bulletin from the University of Arkansas's Division of Agriculture (http://plantpathology.uark.edu/Number5-2009.pdf), I am going to believe for now that the wind currents delivered the herbicide to this one rose only and that it's herbicide damage -- there is no excessive thorn growth.

"Roses are extremely sensitive to herbicides. The most
commonly seen damage is caused by glyphosate drift
(Roundup). The rose pictured below was 40 feet from
the area sprayed with Roundup. The slightest amount of
drift can cause stunted, twisted, cupped, curled, chlorotic
foliage and even death to your plants. Injured plants that
donâÂÂt die may take months to recover. Great care must
be taken with this herbicide. Spray only on windless days.
Studies show that 14-78% of glyphosate can travel as far as 1300 feet downwind. Roses may be covered with a tarp while spraying. Be sure to remove the tarp immediately after the drift has had time to settle. Roundup injury resembles a virus called Rose Rosette Virus. You can tell the difference by examining the thorns. Plants with the virus have an
excessive growth of unusually soft and pliable red or green thorns. Virus is not curable."

Please don't hesitate to comment.
Thank you.

Which ever it is I recommend cutting the affected cane down to the ground as a precaution.

In agreement with Henry and not with the necessity of hyperthorniness as a RRD symptom.

There is too much growth at too many leaf axils, esp when compared with the other canes.

Something else that argues against the herbicide cause. To me it seems as if the problem started out the cane and is moving down. That's the way a phloem transported problem works. Look at the newest red growth on the affected cane....it's at the juncture of another (from last year) cane. The more established problem is out and it's spread downward.

My only problem with your decision is that I can't believe that herbicide damage would express itself in just one week. There seems to be several weeks of growth there. Cut the cane off to the ground and be very watchful of new growth on this bush. If it happens again I'd not take any chances and remove the bush.

I'd probably do what Seil recommends.

Kate

Herbicide damage can result in the spring from herbicide contact with the canes or leaves the previous summer of fall.

"5) Round-Up can cause problems even if sprayed last summer or fall. A quote from Roses: Cultural Practices and Weed Control: "Roses are also very sensitive to glyphosate (Roundup and many other trade names), which can be absorbed through the green stems in addition to the leaves. Glyphosate damage may appear at bud break the following spring after a summer or fall application that contacts leaves or stems; symptoms include a proliferation of small, narrow shoots and leaves.""

From:
http://home.roadrunner.com/~kuska/rose_rosette_disease_virus.htm

Here is a link that might be useful: link for above

Thank you, Everyone, for offering your opinions. I suppose this may be a case of believing what I want to believe. It hard though. I have just a handful of roses that are truly spectacular so far and this is one of them. But. It's better to be safe than sorry. I will cut the cane after work tomorrow. :(

I'm sad. But I am also grateful for this community. So thank you all who took the time to respond. I appreciate you all.

I agree with you Henry. When I had herbicide damage it was from a neighbor who had sprayed in the early spring. My damage didn't show up until mid August. So it can take some time for it to show up which is why I think Sidos' spraying a week ago is not the cause of this damage. Unless he also sprayed with herbicide last fall this could well be RRV.

My husband didn't spray the herbicide last year. I'm not sure what got into his mind this spring and convinced him that he needed to spray. He's never done that before and wouldn't listen to me about it being too breezy. I didn't know that it could take so long for the herbicide damage to appear, that makes me feel even worse, as I saw him spray just inches away from my Veichenblau. Now. Not only do I have to cut a cane out of my A Shropshire Lad, I have all summer to worry about the longer term effects of the stupid spray.

Loving and growing roses is full of joy for me but not without several heartbreaks a season. They really bring out the drama queen in me. ;)

Hopefully the rest of the rose will be okay.

Table 4 and Table 6 give the amount of injury as a function of time when RoundUp is sprayed at bud break and at full leaf at one concentration.
http://www.hriresearch.org/Docs/Publications/JEH/JEH_1999/JEH_1999_17_4/JEH%2017-4-164-167.pdf

Here is a link that might be useful: link for above

Update. A brand new cane shot up immediately after I cut out the infected cane of my A Shropshire Lad. Everything appears healthy so far.

Part of me continued to hope that it was pesticide and not RRD.

Until last night.

On my way out on a date with my husband I noticed an old multiflora rose hanging out of my neighbor's neglected apple tree along the property line.

I went in for a closer look.

And there it was. The RRD.

Just down the hill about 15 - 20 yards in direct line of sight of my infected rose.

My husband ripped out the rose this morning and said it filled the back of his pickup truck to overflowing. He took it to the landfill but felt unable to seal it up.

He also said that he is convinced that roses reach out to grab you when you walk by even if you're several feet away. It didn't go down without a fight, poor thing. :(

Wow good thing you found it!

Oh, Sidos! I'm so sorry!! I am also relieved that you found (and eradicated) the culprit on your neighbor's tree. You have an eagle eye. I bet you'll spot RRD a mile away now, even when it's barely visible. Once having recognized the odd growth, I imagine one develops an ID skill. It's hopeful that you only spotted signs on one of your garden roses. I know gardeners who have lost one or two only while other plants never developed the disease. Fingers crossed that you nailed the source in time. I think that there's a solid chance. Try to relax while you keep your eyes on new growth in your beds and know that one infection does not guarantee an epidemic. If you ever need any cuttings of roses in my garden, they are all yours. You have a wonderful husband! I adore partners with trucks. Thinking of you and sending a hug of encouragement--Carol

Sidos-House, I'm so glad you spotted the multiflora rose. Even if it wasn't RRD this time, it probably would have been just a matter of time. At least your husband made up for his spraying mischance by getting rid of that monster for you.

Yours is such a lovely rose. I'll keep my fingers crossed that it will get to stay in your garden.

Ingrid

As I drive around and look in peoples yards I'm disappointed to not see more people growing roses. Sure they are work, but oh so worth it. Your post reminds me how just not anyone should have roses as with RRD you really do have to be watchful of your plants to ensure they stay disease free and don't spread the disesase. I'm so glad you found the source, and I hope you have stopped it in time. Your Shopshride Lad is beautiful.

I hope you caught everything in time and you have no further outbreaks. Good luck.

Thanks, Everyone, for the support and well wishes! Thanks, Kippy!

Portland Rose, thanks so much. Based on other people's experiences, I am hopeful that I caught everything early on but worrying is in my nature and it's difficult not worry. You have great taste in roses and much more knowledge than I do, so if I had to start all over with only your cuttings I'd have a great beginning.

Oh, Ingrid, I know. He felt so badly! I'm never using that stuff again, he said. But with a little more color, if you know what I mean. I still don't know what he was thinking but it's over now, thank goodness. My ASL is not the most well-behaved rose but I do love it. And would be so unhappy if I had to put it down. And yet, I think about other friends here who have had to take down true heirlooms -- and there is no comparison in the loss.

Thanks, Janet. Hugs! I am hoping too. I have a path lined with roses right in the line of sight from our house to the rose that introduced the RRD and I am hoping it didn't get in there.

MZ, I know! I would have never known about RRD if I had remained casual about growing roses and had not begun to read and participate in the rose forums here. And I would have just kept that growth and let it infect my garden. Like many other people must be doing -- and unknowingly making a problem they don't even know exists worse. :(

Thanks again to all of you.