Webbed structures base roses - Ask Extension
Now that the snow has melted around my roses, I see a webbed structure on every bush. It looks very fragile and probably will disappear with the first...
Knowledgebase
Webbed structures base roses #894273
Asked March 12, 2025, 7:27 PM EDT
Now that the snow has melted around my roses, I see a webbed structure on every bush. It looks very fragile and probably will disappear with the first rain storm. Any ideas?
Grand Traverse County Michigan
Expert Response
Hi Caroline,
It looks like there may be a few things happening with your roses. The white powdery substance on some of the branches looks like powdery mildew.
Powdery mildew is a fungus attacking leaves, stems, and flower parts. Usually, young growth is most severely affected. Reddish, blister-like areas on the upper side of leaves are followed by powdery white growth, which can appear on either side of the leaf. Infected young leaves are often distorted. Flowers and stems will also display the white growth. Some varieties of roses may drop infected leaves, while others are more resistant to powdery mildew. The disease is most active during cool, dry, cloudy weather. Did your roses display signs of powdery mildew at the end of last year's growing season? The disease may have over wintered on the plants.
Click on the link more information on identification and treatment for Powdery Mildew. LINK 611.pdf
The webbing is a little more challenging to id. Spider mite webbing (mites the usual suspect) is finer, and you generally see very small crawling insect. With this being March and the cooler weather if this were spider mites it would have happened last summer/fall at around 80F. So, it may be another spider in your garden that over wintered in the roses and now the webbing has powdery mildew on it.
Hope this information helps. Thank you for using Ask Extension.
Pam
MSUE Master Gardener
It looks like there may be a few things happening with your roses. The white powdery substance on some of the branches looks like powdery mildew.
Powdery mildew is a fungus attacking leaves, stems, and flower parts. Usually, young growth is most severely affected. Reddish, blister-like areas on the upper side of leaves are followed by powdery white growth, which can appear on either side of the leaf. Infected young leaves are often distorted. Flowers and stems will also display the white growth. Some varieties of roses may drop infected leaves, while others are more resistant to powdery mildew. The disease is most active during cool, dry, cloudy weather. Did your roses display signs of powdery mildew at the end of last year's growing season? The disease may have over wintered on the plants.
Click on the link more information on identification and treatment for Powdery Mildew. LINK 611.pdf
The webbing is a little more challenging to id. Spider mite webbing (mites the usual suspect) is finer, and you generally see very small crawling insect. With this being March and the cooler weather if this were spider mites it would have happened last summer/fall at around 80F. So, it may be another spider in your garden that over wintered in the roses and now the webbing has powdery mildew on it.
Hope this information helps. Thank you for using Ask Extension.
Pam
MSUE Master Gardener
