An infallible adage in the gardening world is “If it ain’t one thing, it’s another.” If it isn’t some relatively recent bane like mulberry weed, it is some hitherto unknown disease or plague of some kind or another that strikes just as we think we are getting ahead of the game.
For my part, a big percentage of my gardening time the past few years has been battling mulberry weed. I never heard of it until a few years ago and now it is rampant all over the area. After three years or so of hand weeding, I thought I had just about beat it when, the other day, I was ramping through our overgrown and declining flower borders and found a lot of new stands of it hiding under abundant leafage of other things. They had already dropped seeds aplenty so next year will be no relief.
Then there is the rose rosette disease that has crippled and killed roses by the literal millions all over the place. Some commercial growers have had to destroy thousands of plants that were infected or were located near others that were. It spreads insidiously from bush to bush and can travel by the wind via almost microscopic mites that infect new plants. It is a virus that twists and deforms leaves and ultimately kills the plant. It is incurable, at least for now, and has many gardeners puzzling over what they can substitute for the formerly bullet-proof ‘Knockout’ series of roses that have been planted by the millions everywhere and were hailed as fulfilling the dream of a disease-free rose.
Ironically, ‘Knockout’ roses are particularly subject to rose rosette virus. It is sometimes seen even in dealers’ pots at the point of (potential) sale. I say “potential” because, once spotted, who is going to buy one? A lot of them have been dumped, even by retailers.
Our own meager stand of ‘Knockouts’ consists of some half dozen or so, and, so far (knock on wood) I have observed no infection. It is coming, I am sure.
Rose rosette is nothing new, being first observed in the 1940s and actually was hailed as a possible means of eradicating the common multiflora rose, which plant spreads wildly by seeds throughout a large part of the country. Instead multiflora rose has become an unwitting carrier of the disease. To wit: a couple of years ago friends had a serious outbreak of rose rosette at their home in the country, with several ‘Knockouts’ biting the dust. It so happened there was a huge specimen of multiflora rose across their driveway and, upon close inspection, it was found ridden through and through with rosette. Now which came first, the disease on the tame roses or that on the wild one? It’s a good question, but at any rate, they all were doomed.
Mark Windham, who is testing plants at the University of Tennessee to find resistant varieties, said unless an infected bush is removed promptly, it will spread the disease via mites to other plants in the vicinity. This faces the gardener with tough choices. Remove all others? Remove the infected plant(s) and hope rosette will go away, or what?
Dr. Windham has culled roses at UT down to those that have withstood being infected by surrounding plants, but the tests won’t be complete until a full four years has passed.
There is a (slim) possibility that a rose only slightly infected and caught early can be helped by severely cutting it back, preferably in early spring, well below the infection. But all I can say is, good luck.
As Gen. Halftrack says, “What next?”
JIMMY WILLIAMS is the garden writer for The Post-Intelligencer, where he can be contacted on Mondays at 642-1162.