Insects and Diseases of Trees in the South

by Anonymous

PITCH CANKER

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.

Pitch canker infection in terminal branch and main stem of pine.

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.