Rating the Susceptibility of Stands to Southern Pine Beetle Attack

G.N. Mason - Research Coordinator, IPM RD&A Program for Bark Beetles of Southern Pines,
P.L. Lorio, Jr. - Project Leader and Supervisory Soil Scientist, Forest Insect Research, USDA Forest Service, Southern Forest Experiment Station, Pinesville, LA,
R.P. Belanger - Principal Silviculturist, USDA Forest Service, Southeastern Forest Experiment Station, Athens, GA, and
W.A. Nettleton - Entomologist, Forest Pest Management, USDA Forest Service, Southern Region, State and Private Forestry, Pineville, LA.

Integrated Pest Management Handbook, USDA, Forest Service, Agriculture Handbook No. 645, April 1985.

Introduction Forest managers frequently attempt to minimize losses from the southern pine beetle (SPB), Dendroctonus frontalis Zimmermann, by applying a variety of direct control treatments after an outbreak has developed (Swain and Remion 1981). However, a preventive approach based on recognition and correction of conditions favoring outbreak can reduce the risk of attack and minimize the probability of spot spread throughout the life of the stand (Fig. 1). Stand hazard rating is the key to using these practices.

Figure 1. - Typical mixed southern pine and pine hardwood stands with southern pine beetle spot infestation. Stand hazard rating is a useful tool for helping to manage this destructive pest. (F-705621).

Rating a stand's susceptibility to SPB attack provides information that can be used to identify current or future hazard conditions and to select stands for early treatment for reducing potential SPB losses. Stand ratings may also be used for other purposes such as 1) improving the effectiveness of priority setting for management actions, 2) monitoring pest activity during endemic periods, 3) scheduling direct control treatments, and 4) assessing outbreak and loss potential.

Historically, southern pine beetle outbreaks have developed under a broad range of forest and environmental conditions. Bennett (1965) reported that dense pine stands and slow tree growth were frequently associated with outbreaks in the Gulf Coastal Plain. He further indicated the importance of stand age and composition in relation to susceptibility to bark beetle attack. Lorio and Hodges (1974) suggested that certain soil, tree, and stand characteristics associated with SPB infestations could be used to develop a stand hazard-rating system. Building upon these reports and the observations of others, researchers gathered information on environmental factors associated with SPB activity from more than 3,300 plots in infested and noninfested stands from Virginia to Texas (Coster and Searcy 1981). These and related studies have led to the development of a number of rating systems for a variety of geographic and physiographic areas across the South (Appendix).

Stand ratings can be applied easily. They provide an added dimension for making informed management decisions and are currently being used in a number of management situations. This handbook outlines the benefits of hazard rating, describes methods of application, gives general descriptions of systems, and offers recommendations for specific geographic areas. It also describes how to select and apply a rating system and how to evaluate results.

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