Black Spot of Rose — Diplocarpon rosae

Spotlight Name Archive: Leaf Spots

Spotlight Header Archive: Disease Diagnostics Photo Library

Host: Rose
Symptoms: Black spot appears as circular spots up to 5 mm in diameter. The spots have fringed margins, a diagnostic characteristic that distinguishes this disease from other leaf spots on roses. Under favorable disease conditions, the spots enlarge, then coalesce, forming large, irregularly shaped spots. In susceptible rose varieties, it is common for the foliage to turn yellow and defoliation to occur. Excessive defoliation during the season weakens the plant, increasing its susceptibility to winter kill. Cane lesions are small, pin-head sized purple to reddish spots that are slightly raised with definite margins.
Conditions Favoring Disease: Iris leaf spot thrives in rainy conditions in cool to warm temperatures.
How Pathogen Survives/Disperses: Black spot is a serious problem in most areas where roses are grown. The fungus overwinters as mycelium in diseased leaf litter.
Photo and write up provided by Syngenta Professional Products

(Visited 9 times, 1 visits today)
from Syngenta Horticultural Services

Latest Photos see all »

GPN recognizes 40 industry professionals under the age of 40 who are helping to determine the future of the horticulture industry. These individuals are today’s movers and shakers who are already setting the pace for tomorrow.

75 Applewood Drive, Suite A
P.O. Box 128
Sparta, MI 49345

Get one year of Greenhouse Product News in both print and digital editions for free.
Preview our digital edition »

Interested in reading the print edition of GPN?

Subscribe Today »

Be sure to check
out our sister site.
website development by deyo designs