Armillaria root rot This disease is uncommon but when it occurs, entire fields can be affected. The fungus Armillaria mellea , is omnipresent and affects a wide host range of woody plants. It is always present in pine-oak forests where it attacks those trees present. When these forests are cut for conversion to a blueberry field, the fungus survives on root pieces in the soil. When blueberries are planted, the fungus eventually attacks the young root system and becomes established in the upper root system and the lower crown.
Symptoms are slow to develop and take several growing seasons.
The plants will eventually decline in vigor and have poor fruit production. Entire branches may die and the entire plant can be killed. These tend to be produced in late August or September, depending on the amount of moisture present in the soil. Management of Armillaria root rot. The disease is best avoided through removal of all root pieces harboring the fungus in the soil.