Dahlia Viruses Page 1
Observable Symptoms
Leaf symptoms include mottling, necrotic and ring spots, bubbly
surface, and distortion. Stem symptoms include streaking and soft dark
tissue. Plant symptoms include stunting and generalized wilting. These
symptoms are also symptoms for a variety of other fungal and bacterial
diseases, environmental stresses, and cultural practices.
It is very important to recognize that diagnosis
based on symptoms alone is often misleading and dahlia plants can be
carriers of a virus and show no symptoms whatsoever.
Many of these symptoms are illustrated by the following photographs.
The pictures that appear on these pages are partial shots of several
plants that were tested by Mary Jane Sosler,
Plant Clinic Manager, Colorado State University Cooperative
Extension Plant Clinic, Jefferson County. Mary Jane has had more than 10
years experience as a plant diagnostician and holds a Masters Degree in
Horticulture. She performed serological tests on the plants shown.
Photographs by Ben Lawrence.
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plants tested positive for Tomato
Spotted Wilt Virus and Impatiens
Necrotic Spot Virus. They were negative with regard
to Dahlia Mosaic Virus even though it is very common. Plants
that are infected with any virus, should be destroyed!!
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The pattern on the leaf in the picture at upper right and on the
right is typically referred to as "Oak Leaf". The center
vein appears almost normal. |
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Here on the right the central and major lateral veins are affected.
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Here the central vein is involved but very feint signs of other
veins becoming involved are evident. |
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