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.

Model Summaries - Mountain Risk

Description	Mountain Risk is based upon a discriminant analysis of data representing site, stand, and tree characteristics associated with southern pine beetle activity in the Mountains of the eastern United States. The system is easily applied using the discriminant analysis equation or working directly from the lookup table.
Inputs	1) Proportion of pine (shortleaf, pitch, or Virginia pine) in the stand 2) Radial growth in the last 5 years (inches) Risk estimates may be developed by entering the above information into the following equation: Score= - 1.980 - 3.97 PPS + 2.14 RG where: PPS = proportion of pine (shortleaf, pitch, or Virginia) RG = In (radial growth in the last 5 years in inches x 25.4)
Outputs	A rating class is determined from the score as follows:   Score Risk class > 0.49 Low 0.40 to -0.56 Medium < -0.56 High
	Estimates of SPB Risk may also be determined using rough pine stocking and radial growth categories presented in Table 1.

Table 1 - Risk classes for shortleaf, pitch, or Virginia pine in the southern Appalachian Mountains showing 5-year radial growth values of 0.2 to 0.8 inches.

Pine stocking (percent)	Risk classes
	0.2 in.	0.4 in.	0.6 in.	0.8 in.
20	Low	Low	Low	Low
40	Med	Low	Low	Low
60	High	Low	Low	Low
80	High	Med	Low	Low
100	High	High	Med	Low

 

General Reference	Hedden 1983.
For additional information, contact	Dr. R.L. Hedden Department of Forestry Clemson University Clemson, SC 29631 Telephone: (803) 656-3302

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