COMMON ROSE DISEASES

ROSES

Downy Mildew It impacts roses throughout the United States.

Symptoms:

• infection starts on immature plant growth.
• leaves grow dark purplish to dark brown spots.
• may look like burns made by chemical toxicity.
• wet, cool conditions favor downy mildew infection.

Rust While rust is far-flung, it is consistently a problem in Western states.

Symptoms:

• yellow rust spots show up on the upper side of leaves during cool climate in spring or late fall.
• Infected leaves turn twisted around and dry.
• spores infect leaves if fog, dew or rain happens at temperatures from 55 to 75 degrees F.

Powdery Mildew
Powdery mildew and black spot are the 1-2 blow on roses. It takes place in all parts of United States.

Symptoms:

• powdery mildew commonly appears on new growth, in times of warm, rainless days followed by cool, wet nights.
• new leaves may turn curled or twisted, and the shoots will appear badly distorted.
• sometimes, the top surface of the leaves seems natural, but there is wide fungus growth on the leaf underside.

Suggestion:

• don't place roses in shaded spots, particularly in regions that incline to dry out easy in the morning.

Black Spot
Primarily affects roses.

Symptoms:

• lower leaves of nonresistant plants become spread over with brownish-black spots; finally the leaves yellow and fall off.
  
• serious infestation can entirely defoliate a plant in a period of weeks.
  
• diseased spores are broadcasted by rain and water irrigation.
  
• black spot spreads rapidly in moist or humid, warm climate.
  

Suggestions:

• don't wet foliage.
  
• prune the plant to permit good air circulation between branches.
  

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