Leaf blotch symptoms caused
by Dogwood Anthracnose

Dogwood Anthracnose

Plants Affected

Dogwood anthracnose can affect all flowering dogwood species. The following list is presented in most susceptible to least susceptible: Pacific dogwood (Cornus nuttalii), flowering dogwood (Cornus florida). Kousa dogwood (Cornus kousa) is considered resistant

Symptoms/Damage

Leaves

The most common symptoms are large, brown, irregular shaped blotches with dark brown to purple margins on the leaves. Infection often takes place at the tip, spreading down the midvein, producing a wedge shaped appearance. Infected leaves commonly drop before fall, sometimes defoliating the tree.

Twigs

Infected twigs have sunken spots that are tan to brown with purple borders. The spots will eventually enlarge and girdle the twig, resulting in twig dieback.

Life Cycle

The disease overwinters on dead twigs on the tree, and leaves and twigs on the ground. The diseased leaves discharge thousands of spores into the air that cause infection. Infection occurs in spring on succulent new leaves and stems during wet, mild weather.

Management

Cultural

 Plant disease resistant Kousa dogwoods.

 Prune and destroy all infected twigs, rake and destroy fallen leaves throughout the year.

 Thin the tree canopy for better air circulation.

Organic

 Copper can be applied as an effective fungicide following the same directions for chemical treatment below.

Chemical

 Three to four applications of an approved fungicide starting at bud break until dry weather.

 Dormant treatments in the fall will help reduce overwintering spores.