Forest Pests: Insects, Diseases & Other Damage Agents

Wildfire and Prescribed Fire Forest Health Guide for Georgia Foresters Written by Terry Price, Georgia Forestry Commission Adapted for the web by the Bugwood Network

A wildfire is a fire that is started by accident or malice intent that can result in significant forest damage. Conversely, a prescribed fire is a well-planned controlled fire that accomplishes a desired goal. Georgia averages nearly 9,000 wildfires per year (Table 8) with incendiary and debris burning leading all causes (Table 9).

Table 8: Ten year fire summary for Georgia.

Table 9: Georgia fires by cause (year 2000).

Cause Percent Debris Burning 47 Incendiary 22 Machine 10 Miscellaneous 6 Smoking 4 Lightning 4 Children 4 Railroad 2 Campfire 1

Figure 167A - Fire damage to pine. Tree on left will probably live. Tree on right will probably die and be infested by Ips. photo by John L. Foltz

Not all wildfires are bad for forest health. In fact, many wildfires prove to be beneficial. Assessing the affects of wildfire on standing trees is often done by examining the amount of crown scorch, bark charring and damage to feeder roots. These collectively can indicate fire intensity (Figure 167A). Also the age of the stand and tree species will affect the relative susceptibility to fire. Longleaf pine can withstand fire as early as age two. Conversely, loblolly and slash pines rarely survive a fire before age 6. Dormant season fires are usually less damaging than growing season fires because the buds have hardened off making them less susceptible to heat (up to a point).

A forest stand damaged by wildfire should be evaluated as soon as possible. Pine bark beetles are often attracted to fire damaged trees and can move very rapidly throughout the stand. Hardwoods damaged by fire are often infested with ambrosia beetles and wood borers.

An interesting beetle that is often found attacking the charred bark of southern pines is the bostrichid beetle Rhyzopertha dominica. This insect is probably native to India and will feed on all kinds of stored grains and a wide variety of foods, chiefly cereals. When it attacks the bark of burned pines it produces a reddish-brown, powdery boring dust that resembles that of Ips species (Figure 167B). The beetle does not harm trees and therefore, no control is necessary. It feeds only in the outer bark and does not enter the cambium. Timber managers need to be familiar with this insect because it is often confused with Ips beetles. It would be unfortunate to salvage trees infested with this beetle when it is unnecessary.

Figure 167B photo by Stan Moore

Prescribed fires are vital to maintaining the health of coniferous forests in the South. Fire is an effective tool in killing undesirable hardwood species that compete for soil nutrients and water. Fire releases nutrients that are bound in leaf litter and woody debris on the forest floor. Regardless of the reason for doing a prescribed fire it must be carefully planned under predetermined conditions of fuels, weather and topography.

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