Extension > Garden > Diagnose a problem > What's wrong with my plant? > Annuals and Perennials > Roses > Spots on stems
Roses > Stem > Spots on stems
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Canker
Several different fungi
- Dead branch within otherwise healthy plant
- Light colored blotches or patches, often with a reddish purple border, along dead stem
- Some patches may have flaky, loose or cracked epidermis (surface layer)
- Tiny black bumps may be seen on dead area of stem
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Powdery Mildew
Sphaerotheca pannosa
- Powdery white coating on leaves, stems, flower buds and flower stalks
- Leaf tissue may be tinted red around the infection
- Leaves can be twisted or curved at the site of infection
- Infection often most severe on young leaves
- Typically occurs mid to late summer
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Gray Mold
Botrytis cinerea
- Small red rings or flecks on white or light colored petals
- Brown irregular spots on petals
- Completely brown, curled over, dead flower buds
- Brown sunken area on stem
- Gray fuzzy spores produced in cool wet weather
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Black Spot
Diplocarpon roseae
- Purplish black spots with uneven or feathery edges on leaves
- Leaves turn yellow around spots
- Leaves fall off
- Sometimes reddish purple or black blisters on canes
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Rose Streak
Rose Streak Virus
- Symptoms are most common on roses with large clusters of small flowers
- Symptoms may vary in other cultivars
- Leaves turn yellow and may have random dead brown spots
- Leaves fall off in the spring or early summer
- Very susceptible cultivars have brown to black streaks on the canes
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- - NO PHOTO AVAILABLE -
Verticillium Wilt
Verticillium dahliae and Verticillium ablo-atrum
- Tips of young canes wilt
- Leaves turn yellow, then brown and then fall off
- Damage starts on the lowest leaves first and then moves upward
- Canes die and turn brown from the tip down
- Purplish black streaks occur on stems before they dieback
