Corona Virus? No, Rosette!

While we sit and ponder the fate of mankind watching the hyped up news about the spread of the nefarious Corona Virus, another virus is sneaking into our rose gardens, decimating one rose bush after another, and it is planning (if viruses do such things) of ruling the rose world. Have you ever noticed a pinkish tint to emerging rose shoots and the ends of stems flourishing in leaves and thorns? That’s a symptom of the Rose Rosette virus and the culprit is a very small mite that is lodged in stem and root. He is the vector that carries the virus from bush to bush. Wind carries the mite to the next bush in line or perhaps your pruning shears will offer him safe transit from a cut stem to another plant’s pruned stem. Either way, he quickly gets re-established and the virus resumes its activities in a new home and within the year, you will see malformations in leaves, stems, and thorns.

A telltale sign of Rose Rosette Virus is a grouping of reddish leaves on the end of a stem.

Can you spray some mite seeking chemical? No, that will have no effect on the virus. Can you simply chop away at the pink leaves and extra thorns? No, as the mite and virus are present all the way to the roots. What can I do then? Unfortunately, you must pull the bush up from its earthly home and destroy it – preferably by burning. There is no other way. Leaving an infected rose bush alone will invariably spread the mite and virus to all its neighbors. Don’t forget to disinfect any tools you used on the infected rose to kill any mites that might be looking for a new home and our lurking on the scissors’ edge. Do not replant a new rose in the same spot! Remember mites were in the roots and you did not, could not. remove every fibrous root from the old bush.

Knockout roses can be in full bloom and appear healthy and still harbor the mite and virus.
The infected stem becomes covered in thousands of tiny thorns.

Will the mite and its buddy virus infect the Gardenia, the Hydrangea, or, heaven forbid, my Azaleas? No, the mite and virus are rose specific and no damage will be transferred to another species including man. Then what are we to do? Other than destroying infected plants, all we can do is wait for researchers and botanists to figure out an effective curtailment and eradication plan. Many university groups are working on the issue but so far no effective preventive or corrective measures have been successful. The mite is stubborn and the virus, like most viruses, is resistant to chemical and biological controls.

The Mite! Notice the scale at left… the white line is 20 millionths of a meter… The mite carries the virus and the virus is the culprit get rid of the mite and perhaps the virus will disappear too!

The mite itself is probably the solution in disguise. You can’t see the little bugger without a microscope and only the most powerful electron microscopes can resolve the Rosette Virus. getting a genetic code of the tiny mite is difficult but perhaps is the basis for combating its activities. The more we understand about the mite’s makeup, activities, and life cycle the better we can find and counter any apparent weakness.

Knockout Roses can be a beautiful addition to the home landscape.

So until scientific research brings us a solution, be on the lookout for the Rosette Virus telltale symptoms. Don’t but nursery or box store bushes that are suspect. Landscapers will install infected bushes in new homes – our daughter’s home was new and there was the infected rose bush! The installers just plopped a rose in the hole and apparently had no or little training on how to spot the virus. If you see an infected bush for sale bring it to a salesperson’s attention and if their eyes start to glaze over, then approach their manager.

Rose Rosette Virus can’t be stopped once it infects a rose bush so as painful as it may be, destroy that bush and don’t plant another rose in that same spot. Be gone mite – be gone virus! Let us enjoy our roses without fear!

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