logo: University of Minnesota Extension Gardening Information

What's wrong with my plant?

Roses > Stem > Spots on stems

1 of 6
  • Canker 1
    Credit: Michelle Grabowski
  • Canker 2

    Credit: Michelle Grabowski

  • Canker 3

    Credit: Michelle Grabowski

  • - CLICK PHOTOS TO ENLARGE -

green arrowCanker
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
2 of 6
  • Powdery Mildew 1
    Credit: Michelle Grabowski
  • Powdery Mildew 2

    Credit: Michelle Grabowski

  • Powdery Mildew 3

    Credit: Michelle Grabowski

  • - CLICK PHOTOS TO ENLARGE -

green arrowPowdery 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
3 of 6
  • Gray Mold 1
    Credit: Michelle Grabowski
  • Gray Mold 2

    Credit: Michelle Grabowski

  • Gray Mold 3

    Credit: Michelle Grabowski

  • - CLICK PHOTOS TO ENLARGE -

green arrowGray 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
4 of 6
  • Black Spot 1
    Credit: Michelle Grabowski
  • Black Spot 2

    Credit: Michelle Grabowski

  • Black Spot 3

    Credit: Michelle Grabowski

  • - CLICK PHOTOS TO ENLARGE -

green arrowBlack 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
5 of 6
  • Rose Streak 1
    Credit: David Zlesak
  • Rose Streak 2

    Credit: David Zlesak

  • - CLICK PHOTOS TO ENLARGE -

green arrowRose 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
6 of 6
  • - NO PHOTO AVAILABLE -

green arrowVerticillium 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

Don't see what you're looking for?