Rosette disease in roses


I have 3 David Austin Roses that have developed rosette disease – how common is this in Toronto – how do I dispose of them? Do I have to remove soil?
I may have planted the roses too close together ? Can I plant again? Very disappointed


Rose Rosette Disease (RRD), a viral disease transmitted by a small wingless eriophyid mite, causes the formation of deformed stems, leaves and flowers; see What to Look For for photos of infected plants. According to the Fine Gardening article Rose Rosette Disease: Are the Knock-Out Roses to blame?, the main rose that is responsible for the spread of this disease is the wild rose R. multiflora.

Virus transmission occurs most readily between the months of May through mid-July when plants are actively growing. Symptoms from new infections usually start appearing in mid-July. The wingless mite that transmits RRD moves between roses on gusts of wind and clothing. The mites prefer the young supple growth at the top of the rose. The disease appears to affect one cane at a time and moves very slowly  down the infected cane  towards the base. Therefore, if you notice the disease early enough you can remove the infected cane at the base before it reaches the base of the rose and spreads to the rest of the plant.

Now that all three of your roses are infected you must ensure that all parts of the infected roses are removed. Before you dig out the plant, care must be taken to prevent the spread of the mite that spreads the disease. Bag the plant before its removal. Cut off the above ground growth at ground level then dig out the plant’s roots. Make sure every bit of the roots are removed because any new rose planted in that spot may intertwine with left over infected roots of the old plant and get RRD. Once all three plants are dug out make sure to disinfect your tools with a 10% bleach solution as well as putting on clean clothes before moving to a disease-free area of your garden. Make sure not to put any part of your rose in your yard waste or compost. Dispose of all plant debris in the garbage.

Lastly, when planting any rose it is important  not to plant them too close; this will help in the reduction of the mite movement. The Missouri Botanical garden has an excellent article on Rose Rossette and some Integrated Pest Management Strategies on controlling this disease.

October 28, 2021