Wet cool weather and rose problems

Asked October 2, 2019, 4:13 PM EDT

This constant wet cool weather is killing my David Austin roses I planted this year! I’ve been battling everything from what I thought was black spot to bortytis blight to rose rosette. What can I do to protect my roses? Will they survive the winter?

Oakland County Michigan roses rose diseases

1 Response

Hello,

If you are sure the shrub has rose rosette disease (RRD) the only solution is complete removal of the shrub, roots and all mulch and plant material scattered on the ground. Do not plant roses or their relatives in this same spot. To confirm diagnosis send pictures along with bagged and sealed

plants samples to MSU Plant and Pest Diagnostic lab

https://www.canr.msu.edu/pestid/

The diseases are minimized by keep good air circulation around plants, mulch with clean mulch to prevent soil splashing onto leaves, and watering from below so leaves stay dry. Start with healthy plants, fresh potting soil and sanitized pots, if they are in pots.

We have had a rainy season here throughout the season- this keeps rose leaves too wet for too long. Fungicides applied after each heavy rain will help. Always follow the label directions when using garden chemicals and fertilizers.

The roses may survive the winter. Keep all debris picked up and discarded. When the ground is frozen cover the roses with a mound of fresh clean mulch. Leave it in place until early spring when you see plants starting to bud. Pull the mulch back from the stems and the base of the plant. Wait for warm spring weather and watch for buds to start on the roses. You can prune back and dry brittle brown stems at that time. Here are details- https://web.extension.illinois.edu/roses/winter.cfm

Season long, follow a rose care plan such as this- http://rocklandcce.org/resources/rose-care

Here are some references should you need them-

https://bygl.osu.edu/node/1113

https://extension.psu.edu/rose-diseases-outdoors

https://hgic.clemson.edu/factsheet/rose-diseases/

https://hortnews.extension.iastate.edu/1994/3-16-1994/clean.html

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