Friday, July 26, 2013

Rose Rosette Disease

Rose Rosette Disease.

I've been out of the horticulture world for a while. I garden a lot, I learned a bit of plant taxonomy, took classes in plant propagation, helped build a greenhouse, toured nurseries around the northwest corner of Oregon, and drove my husband crazy by collecting plant samples and drying them in weird places in the house and spewing Latin names as we drove through neighborhoods while studying for exams.

This disease was never mentioned in class. It snuck up on me.

Part of the reason is because it hasn't officially blipped on the radar in this area. Part of it is because thanks to a newly-developed test and the devastating loss of some important rose gardens, in 2011 RRD and the rose rosette virus have gained new attention.

It has no cure. Roses that have the disease have to be destroyed, and no new rose may be planted in its place, as the roots remaining in the ground may transmit the virus to the new rose. This disease has destroyed a huge number of wild roses, and many healthy wild roses are destroyed in an effort to restrict the spread of this disease.

The primary vector appears to be a particular sort of wingless mite that doesn't appear to live in this area, and so it may be that my other roses won't be affected, but it may also be true that they're already infected, and I'll lose them all. As symptoms arise, I'll destroy plants, and in their place put lavender and rosemary and peonies and try not to think about how much I loved the scent of all those blossoms in the early morning as I walked down my favorite paths.

I suspect that the rose was infected when I bought it, probably through root stock or a graft purchased from a nursery in an infected region. Last fall, the rose sent up a bizarre shoot. I thought it might be just a weird sport, and wondered if it would bloom. It did, beautifully. The stem remained red, as did all the leaves, and the stem was covered almost completely in thorns. It grew so tall and thick and fast that it easily broke in the next strong wind. Very short side shoots developed, with more rose buds, and one more bloomed. None of the side stems grew more than a couple of inches--unusual for a knocked down branch that bothers to grow side shoots.

In the spring, my husband accidentally mowed it where it lay. The grass had covered it up. I snipped it and forgot about it.

While surfing I ran across an article about the disease, and my heart sank. The stem covered in thorns, the red foliage that didn't mature to green, the very lush, brittle growth ... I had everything except the witch's brooms, elongated and twisted leaves and short stems growing in profusion from a single node, eventually forming 'brooms'. The next morning I went out. That weird stem was long gone, of course, but I had the rest of the plant to look at. It looked normal, except ... the red leaves at the growing tips looked twisted and puckered. No more stems covered in thorns, but .... I emailed our county master gardener program. They concurred with my assessment. Dig it up, burn it. Don't wait for more symptoms. Even if the rest of the rose isn't blaring signs of the disease, even though those leaves might be twisting for other reasons, even though the leaves may eventually turn green, because the rose was probably infected via a graft or root stock, because there's no cure ... there wasn't much point in waiting to see if the rose might not be okay. It wouldn't be.

I may have unwittingly spread the disease. I didn't disinfect the clippers after I clipped off what I thought was a weird sport. I don't have a lot of problems with powdery mildew, and black spot is endemic ... all my roses have at least a little black spot, and so I don't worry about making that worse.

That lack of foresight and basic sanitary practice may have cost me my rose garden. There are always diseases, known and unknown, ready to arise in all our gardens that could kill living things that we prize and that rely on us for their survival. Sloppiness, laziness ... it's easy, but it's risky. I gambled. We'll see how much I lost. Maybe nothing. Maybe just the one rose, a rose I didn't infect, a rose that came infected, that was dying, though neither of us knew it. I surely hope so. Because I have some great roses, and I'd like them to stick around a long, long time.

No comments: