Armillaria
root rot
Armillaria mellea, A.
ostoyae (fungi)
Annemiek Schilder,
MSU Plant Pathology
Bill
Cline, NCSU Plant
Pathology |
 |
Armillaria
root rot is rare on blueberries in the United States, but
can cause serious damage where it occurs.
Symptoms
Infected plants
are low in vigor and may appear to be suffering from a nutrient
deficiency. Leaves are small and chlorotic, and branches
wilt suddenly. Plants decline slowly over several years
or die within a short time. |
| Bush decline due to Armillaria root rot. |
|
White mycelial fans
are present between the bark and the hardwood at or slightly below
the soil line. Black shoestring-like strands (rhizomorphs) may
be attached to the roots or trunk or growing freely in the soil.
Yellowish brown mushrooms (honey mushrooms) are sometimes produced
in clumps at the base of the bush. |
Disease
cycle
The fungus attacks more than 500 species of woody
plants. The disease is most likely to occur on a sandy, well-drained
site where an oak forest was cleared. Armillaria survives as mycelium
and rhizomorphs on old roots and stumps. The fungus spreads between
bushes by root-to-root contact and can also survive on wood chip
mulches. Spores disseminated from the mushrooms probably are not
important in spread.
Management
Disk soil thoroughly if forest (particularly oak)
was present at the site and remove as many root fragments as possible;
leave the area fallow for at least 3 years; fumigate soil before
planting (however, fumigants do not penetrate deeper than 50 cm);
remove and burn infected bushes; remove wood chip mulch. |
