Introduction
Flowering dogwood is popular because of its display of flowers and its bright berries in the fall. However, this plant is very vulnerable to many different diseases. Dogwood diseases are diseases the flowering and pacific dogwood. These dogwood diseases are caused by anthracnose fungus. This fungus is favored by cool, wet springs and fall weather but can be present throughout the growth period. During times of drought and winter, trees tend to be weak and hence are prone to many diseases. Dogwood diseases can be fatal and very destructive if not well treated and prevented.
Symptoms of dogwood diseases
- Leaves: Dogwood diseases symptoms occur on the leaf's lower crown before progressing to the whole tree. Leaf symptoms include; tan spots that develop purple rims, necrotic veins and large necrotic blotches, shot holes and premature abscission of leaves.
- Twigs: Girding cankers often develop leaf nodes leading to death of the twig. Fall blighting of terminal leaves that results to death of terminal buds. This leads to dogwood diseases refoliation through axial buds. Twig die-back is common in the lower crown.
- Epicormic branches: Due to twig die-back, succulent shoots proliferate on the lower trunk and the main branches of affected trees. The branches are very prone to dogwood diseases infections which sometimes progress to the main stem.
- Main branches and trunk: Brown elliptical cankers form at the base of dead main branches causing swelling and split barks. Multiple cankers girdle the main branches and end killing the entire tree.
- Bracts: Bracts become spotted if there is a lot of rain during flowering season.
Prevention of dogwood diseases
- Use propiconazole, azoxystrobin, myclobutanil, thiophanate methyl + mancozeb, chlorothalonil, or mancozeb, to protect new flowers, foliage and twigs during bud break.
- Apply azoxystrobin, myclobutanil, chlorothalonil, potassium bicarbonate, polyoxin, or triadimefon as soon as symptoms present themselves.
- Get rid of infected trees and do not replace it until the soil is fumigated and aerated.
- Apply mefenoxam to the trees near the dogwood diseases infected one to prevent invasion.
- Plant dogwood diseases resistant trees like Kousa dogwood and hybrids of kousa and native dogwood to replace the dying infected trees.
- Avoid overhead watering as it increases the chances of leaf infection.
- Improve the air circulation around the tree to assist in drying the foliage and reduce the chances of dogwood diseases infection.
Tips and comments
- Select healthy trees to cultivate: Purchase trees from a reputable nursery and avoid planting trees from mountainous areas.
- Know and understand the dogwood diseases that are common in your area.
- Adopt proper planting techniques: prepare deep holes of about 18 inches and 3 feet diameter, fill it with a mixture containing 1/3 organic matter and 2/3 soil. Dogwood diseases advance best in high organic matter soil.
- Choose a good planting site to promote vigor and rapid drying of foliage. Avoid sites with high moisture.
- Completely remove and prune dead woods and leaves each year.
- Use the right amount of fertilizer according to the soil analysis.
- Avoid chemical and mechanical damage to trees as they provide entry to pathogenic fungi.
- Use 3-4 inch deep mulch at a three foot radius around established trees and ensure that the mulch does not come to contact with the trunk.
