I'm climbing up on my soapbox again. Just skip to the next post if you've already heard this....
RRD is rampant in our area. Multiflora rose is rampant here, too. That's no coincidence, but that story is for another day. Airborne mites carry a virus-like RRD, and that is what causes the spread of RRD. It's not production techniques or parentage of the rose.
In our area, like many others, Knock Out roses are widely used in commercial plantings. They are an excellent choice for any business that wants easily maintained color for 7 straight months.
The problem arises when the roses are planted too close together, and landscape crews who are asked to maintain a certain height on the roses take the easy way out and use powered hedge trimmers. They move through the beds quickly, and the virus in the "sap" of the rose is carried from one rose to another. That's not to say that one infected rose wouldn't spread the virus through all of them eventually, but it happens more quickly through the trimming.
If the roses were spaced further apart, the way they are in a residential setting, it would take longer to spread. Hopefully the gardener would notice the first infected rose, remove it, and keep the disease from spreading, at least until another mite starts the process over.
Here, commercial maintenance crews often do not speak English and they definitely don't have the authority to remove plants. I know of one retail area that removed all of their infected Knock Out roses, replacing them with Drift roses. The next season, all the Drift roses had RRD. Last fall, they replaced the Drift roses with potentilla.
I guess I should be glad they got them out before people started "hating" the Drift series. Folks, Knock Out and Drift are not the source of the problem! It's wild infected multiflora and a tiny mite.
About 12 years ago, there was quite a discussion on Garden Web with people strongly hating Hybrid Teas because they had so many problems with blackspot. That time, it was both a weakness of the class of rose and of cultivation. Now there's many more disease-resistant Hybrid Teas and I think people are more aware of watering and cleaning. The gardening public spoke, and now we have much needed improvements on both ends.
I remember years ago when 'Blaze' and 'Eutin' were in every yard. My parents scoffed at how boring and common they were. I guess that's what keeps hybridizers in business, isn't it? If something is easy, successful, affordable, and everybody has it, well, it's not for "us".
May Night Salvia, Stella d'Oro daylily, and Karl Foerster grass get the same "overused, boring" rap. Well you know what? They grow. They don't need you to suit up and spray chemicals. You don't have to water them every day. You don't have to pick bugs off of them. Your average Joe can come home from work and look at pretty blooms in their yard and smile and say yes, I can grow flowers. So what if every third house on the block has the same plants. We need to show people more easy care flowers like this, and then quit criticizing them when they grow them.
Rant over.
