Figure 1. Diseased bud affected by Phoma ligulicola.
Figure 2. Numerous dark pycnidia of Phoma ligulicola in infected pyrethrum plant tissue.
Contributed by Dr. Sarah Jane Pethybridge University of Tasmania – North West CentreP.O. Box 3523, Burnie, Tasmania 7320, Australia email@example.com
Host: Tanacetum cineariifolium (pyrethrum) Disease name: Ray BlightPathogen name: Phoma ligulicolaRay blight is the most severe fungal, foliar disease of pyrethrum in Tasmania, Australia. Since its first description in 1995, it has caused significant losses annually. Outbreaks generally occur in early spring and affect all above ground parts of the pyrethrum plant. The disease does not affect roots, but the pathogen is able to survive as epiphytic mycelium around root cuttings. This is one way it is transmitted symptomlessly on chrysanthemum and pyrethrum cuttings. The flower phase of the disease (figure 1) is the most characteristic symptom of the disease. Other symptoms include necrotic spots on leaves and lesions on stems. Signs include numerous pycnidia in infected tissue (figure 2).
APS publication number: IW000029
Picture your photograph as the APS Featured
Click here to find out more
License to Copy. This
notice hereby grants permission to APS users to copy the image featured for
noncommercial, personal use. All components of APSnet are copyrighted and may
not be reproduced or distributed except by express permission of APS. Copyright
is not claimed for material provided by United States government employees as
part of their work. APS copyright extends to images, text, graphics,
photographs, illustrations, audio, video, computer software, and all other
elements of the site.Instructions to Copy. For PC, position your mouse
cursor on the featured image, click the right mouse button, and choose "Save
Picture As..." or "Save this Image as..." whichever is the case. For Mac, click
the only mouse button and follow the same steps. Users may want to set up a
specific directory and file naming scheme for storing images; otherwise, they
will be saved using your system defaults. Images may be used in any software
application that supports JPEG file format or viewed in an Internet browser as