Two
types of spores are produced in the stromata. Conidia can be squeezed out in
long tendrils like toothpaste, such as seen here. These can be spread to
other trees in rain splash or stick to the feet of birds or other animals to
be transported extremely long distances. Ascospores are the second spore type. The windborne
ascospores are responsible for most spread of the disease over intermediate distances,
from
about 5 feet to 500 yards.
Each
stroma can produce thousands of both types of spores. Overall, billions and billions are produced on each tree.