Forest Pests: Insects, Diseases & Other Damage Agents

Conifer Canker Pitch Canker Forest Health Guide for Georgia Foresters Written by Terry Price, Georgia Forestry Commission Adapted for the web by the Bugwood Network

The pitch canker fungus, Fusarium subglutinans, can infect most of the southern pines but more damage is done to slash, shortleaf and Virginia pines. It gains entrance into trees through wounds and insect feeding sites made by pine tip moths, the deodar weevil and beetles in the genus Pityophthorus. After the fungus gains entrance into the tree, the tips of terminal and lateral branches are often girdled and killed (Figure 143). Upon close examination of the dead shoots, the wood will be pitch soaked beneath the bark (Figure 144). The fungus also causes trunk cankers. Plantations adjacent to chicken houses are often infected with the pitch canker fungus. The fungus apparently likes the high concentrations of ammonia that’s absorbed by pine needles and shoots.

Figure 143 photo by L.D. Dwinell

Figure 144 photo by L.D. Dwinell

The disease has not been a serious problem to pine plantations in Georgia, however, since the disease has the potential to outbreak (sporadically), the land manager should be aware of its presence.

Several management options are available for managing the disease in slash pine plantations:

• Infected trees should be removed during thinnings.
• When regenerating stands, consider using the seed tree method because native seed sources may be more disease resistant than nursery seedlings from a particular seed source.
• Regulate stocking densities to avoid over crowding and individual tree stress.

Management guidelines for seed orchards:

• Avoid damage to trees from shakers, boom trucks and other equipment. Inform personnel on the proper handling of equipment and the importance of not wounding trees.
• Rogued trees should be sold or burned and not left as breeding sites for weevils and beetles.

Management guidelines for Christmas tree plantations:

• Sell or remove all infected trees as soon as possible.
• Pruning provides ideal wound sites for pitch canker to invade. In areas where pitch canker is prevalent, favor eastern red cedar over Virginia and white pines since these two species are susceptible to the fungus.
• Over fertilization may enhance pitch canker infections.

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