Black spot (roses)

From Wikipedia, the free encyclopedia

This article is about the disease of roses, for blackspot of strawberries see Colletotrichum acutatum,

for the definition relating to pirates, see The Black Spot.

Black Spot or Black Spot of Rose is a disease common to roses, caused by the fungus Diplocarpon rosae. The name of the disease comes from its effect on the plant; it causes black spots to appear on leaves, which eventually yellow and die.

[edit] Diagnosis

The black spots are circular with a perforated edge, and reach a diameter of 14mm. Badly affected plants, however, will not show the circular pattening, as they combine to cause a large black mass. The common treatment of the disease, is to remove the affected leaves, and spraying with anti-fungal solutions. Some stems of the roses may become affected if untreated, and will cause progressive weakening of the plant.

[edit] Treatment

It is usually recommended to remove the plant, as it will not yield well, and will slow the spreading of the disease. Removing fallen leaves helps to avoid the infection. Fungicides - for example mancozeb, chlorothalonil, flutriafol, penconazole, or a copper based product- applied upon new leaf emergence or first appearance of black spot can be used to control the disease. Several sprays may be required to keep the disease under control during the growing season.

[edit] References

• Black Spot of Rose at the University of Maine
• Black Spot of Rose at the University of Nebraska-Lincoln
• Rose blackspot at the Royal Horticultural Society