virus in soil kills roses

Asked June 3, 2015, 11:32 AM EDT

I have had a rose bed in the same spot for at least 10 years. The last two years the new bushes I have planted have struggled and only grown about one foot tall. This spring the branches turned black on most of the bushes ( old and new) and most did not leaf out. I dug up all plants and took to local garden center. They concluded that there was some unnamed virus in the soil and I would not be able to plant roses there any more. In the meantime, my husband had tilled the area and added composted manure, so the soil is not exactly the same composition that it was. Can it still be determined whether/ what virus may be the problem? How do I do that? Is there any remedy for this problem, so that I can plant roses there?

Clackamas County Oregon disease issues roses horticulture soil and fertility issues

1 Response

Well, no, you would not have a virus of any kind that I know about causing this problem. Even if you had brought a virus in with the new plants it would be slow to spread and not affect every plant that quickly.
The most dominate problem affecting plants this year is frost/winter injury from way back in November last year. Many of our woody perennials were still growing strong or had leaves on when the temperature finally dropped in mid-November. Many of these deciduous plants with injury had leaves frozen on the stem during this event. If your roses were still growing strong they may not have hardened off and likely sustained cold damage during this event. If this is what happened then there would be no residual effect and you are clear to plant away in this bed.

But lets be cautious and think about if there were something that might linger in the soil just in case my diagnosis (based on this little bit of information) is wrong. Crown gall is a bacterial problem we do have and can be brought in on plants. You would see galls on the stem or roots or root crown area just under the soil. I suspect you would have seen those on the plants you dug up so I am ruling that out. It may still be in the soil so being careful not to injury any new plants when planting will be important.
Nematodes can be troublesome in some areas, especially in sandy soils. The symptoms you describe are not consistent with injury by these roundworms. There are a number of fungi and similar organisms that can cause root rots on rose. Again they would move slower and are not likely problems.
Replant problem is something they talk about in Europe but we have not confirmed it in Oregon anywhere for roses. You might find rose would do better in other areas of the yard. In fact, it would be interesting to plant the same type of plant in this bed and another that has never seen roses and see how they do. In any case, the Portland rose garden routinely digs up 1,000s of roses, replants after doing what you have done to your rose bed, and they do very well. See here:
http://pnwhandbooks.org/plantdisease/rose-rosa-spp-and-hybrids-replant-disease

Bottom line - go ahead and plant roses in the same bed. Be careful not to injure roots when you plant. Take good care of them this summer but do not fertilize too late in the year. Good luck!