Rose Black Spot
Class: Fungi
Common Name
Rose black spot
Scientific name
Diplocarpon rosae
Potential Hosts
Roses
Who am I?
Rose black spot is an important fungal disease of roses that is mostly active towards the end of spring. The fungus overwinters in infected plant debris from the previous season.
The fungus causes black spots to form on the upper surfaces of leaves. Defoliation can occur in heavily infected plants. Rain, overhead irrigation, and any other water-splashing sources triggers spores from infected plants debris.
Rose black spot tolerates a broad range of weather conditions, thus it allows symptoms to develop throughout the season.
Control measures
Cultural
Plant resistant varieties: Planting roses that are resistant to black is the most effective strategy for prevention.
Sanitation: Dispose of diseased leaves and other plant debris that fell off. Don't use infected plants parts in composts.
Conventional (chemical)
The following are generic names of fungicides used in one or more parts of the world: azoxystrobin, trifloxystrobin, Myclobutanil, penconazole, pyraclostrobin, and kresoxim-methyl.
Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.