Dogwood anthracnose, caused by the fungus _Elsinoe corni_, occurs in
states bordering the Atlantic Ocean and has also been reported in
Louisiana. Its primary host is flowering dogwood, _Cornus florida_ L.
[Illustration: Leaf and flower symptoms of dogwood anthracnose.]
[Illustration: (cont.)]
Anthracnose occurs in the spring and affects not only the leaves, but
also the buds and “flowers”. The buds may fail to open or they may
produce stunted flowers. These have many circular to elongated spots
with light tan centers. Margins of these spots are purple to brown.
Often the flowers abort before development. Foliage spots (1-2 mm. in
diameter) are raised at the margins. They are purple at the edges and
yellow-gray in the center. Later centers of spots may fall out causing a
“shothole” effect. Dozens of spots may be present on a single leaf and
may be scattered or concentrated at tip, margin, or midrib. Twisting and
malformation of the leaves are common. In addition to floral and foliage
spots, infected areas may also occur on petioles, stems, and fruit
clusters. All three areas have spots similar to those on the foliage.
Other diseases which may be confused with anthracnose include _Septoria_
and _Ascochyta_ leaf spots. _Septoria_ usually begins around July and
unlike anthracnose has more angular lesions that are between the veins.
_Ascochyta_ spots may be larger (6 mm. in diameter) than anthracnose,
and tissue discoloration may extend outside of their borders.
Occasionally the leaves may totally blacken. This disease may occur as
early as June.
Wet, humid weather at certain stages of plant development is required
for infection. Homeowners may obtain effective control by removing and
burning infected plant parts. Various fungicide sprays are recommended
by authors of ornamental handbooks.