Downy Mildew of Roses

Peronospora sparsa

Description:

A fungal disease that causes round to angular, dark brown to reddish spots on leaves. Furry hyphal growth may appear on the underside of the leaf opposite the spots. In severe cases young shoots may die and leaves prematurely fall.
Stems and flowers stalks may develop purples blotches and streaks and may split.
Flowers may be deformed if buds are infected, petals may have brown patches and sepals have purplish brown spots.

Species Affected:

Roses. Some varieties are more susceptible than others.

Biology:

Favoured by humid weather.
Spores are wind borne.

Life Cycle:

Origin and History:

Distribution:

Significance:

Management and Control:

Plant more tolerant varieties.
Destroy infected leaves and prunings.
Apply fungicides.
Maintain low humidity and horizontal airflows in glasshouses.

Related and Similar Species:

1291

References:

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.