Pitch canker, caused by the fungus _Fusarium lateritium forma pini_, is
rapidly becoming widespread throughout the South. The disease apparently
is most serious on Virginia, slash and south Florida slash pine. The
fungus also attacks shortleaf, pitch, and table-mountain pine.
[Illustration: Pitch canker infection in terminal branch and main
stem of pine.]
[Illustration: (cont.)]
Pitch canker may cause tree mortality. On Virginia pines the fungus
reportedly enters through small insect wounds in the twigs or mechanical
wounds in the bole. Shoots may be girdled and killed within a few weeks,
but it takes a period of years for the fungus to girdle the bole of
larger trees. On slash pine the disease apparently attacks plantations
in wave years. During years of heavy attack the fungus can cause rapid
crown deterioration in addition to causing bole canker infections.
Cankers on leaders in the crown can result in death of two-thirds or
more of the crown by mid-summer in a tree that appeared healthy in the
spring. In the majority of tree infections only the leader and one or
two laterals will be infected. The tree recovers in a few years with a
crook in the bole as the only evidence of attack. Pitch cankers usually
retain the bark and old cankers on the hole may be sunken. The most
diagnostic characteristic of the disease, and the one that definitely
separates it from similar disease, is the heavy pitch soak of the wood
beneath the canker. Pitch cankers are often so soaked with pitch that
heavy flow of pitch is observed flowing down the bole.
At the present time, no known method of control exists. Observations in
slash pine plantations indicate that some trees are resistant while
others range in their degree of susceptibility.