Black Spot of Roses

Diplocarpon rosae

Marssonina rosae

Description:

A fungal disease that causes circular, black spots on leaves up to 12 mm diameter. The edges of the spots are irregular or fringed. Leaves turn yellow and fall as the disease progresses. Plants continually infected are weakened, have fewer and smaller flowers and may show die back of branches or succumb to other diseases. On very susceptible varieties young stems may also be affected.

Species Affected:

Roses.

Biology:

Favoured by humid weather with temperatures between 13 and 240C.

Life Cycle:

Origin and History:

Distribution:

Significance:

Management and Control:

Avoid cultivars that are badly affected.
Reduce humidity around plants. Avoid growing smaller plants underneath Roses.
Water early in the day.
Destroy diseased leaves.
Apply fungicides.

Related and Similar Species:

References:

1291

Acknowledgments:

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