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Diplocarpon rosae is a fungus that causes the rose disease Black Spot.[1] Because it was observed by people of various countries around the same time (around 1830), the nomenclature for the fungus varied with about 25 different names. The asexual stage is now known to be Marssonina rosae while the sexual and most common stage is known as Diplocarpon rosae.
Diplocarpon rosae over seasons as mycelia, ascospores, and conidia in infected leaves and canes. In the spring during moist, humid conditions, ascospores and conidia are wind-borne and rain splashed to newly emerging leaf tissue. Upon infection, disease progresses from the lowest leaves upward causing defoliation and black spots on leaves.[citation needed]
[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
- University of Nebraska page on Black Spot of Rose[1]
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- ^ McMaugh, J. What plants pest or disease is that?, New Holland Publishing, Sydney, 2006, ISBN 1864366990, page 231
[edit] External links
