United States 

Department of 

Agriculture

Forest 

Service 

Intermountain 

Region 

Forest Health Protection 

Boise Field Office 

1249 South Vinnell Way, Suite 200 

Boise, ID 83709-1663

 Caring for the Land and Serving People Printed on Recycled Paper 

File Code: 3420 Date: October 9, 2003 

Route To: 

Subject: Verbenone in Administrative Areas, Sawtooth National Recreation Area, Pettit 

Lake 

To: Forest Supervisor, Sawtooth NF 

 

 

At the request of SNRA personnel, Boise Field Office Forest Health Protection (FHP) personnel 

have been applying the mountain pine beetle antiaggregant verbenone to lodgepole trees among 

summer homes and administrative areas around Pettit Lake from 2001-2003. The enclosed 

report (BFO-PR-04-01) summarizes the results of the verbenone trial over the past 3 years. 

Please contact Rob Progar or Dayle Bennett if you need additional information or assistance. 

/s/ Dayle D. Bennett (for) 

WILLIAM W. BOETTCHER 

Director, State and Private Forestry 

 

Enclosure 

cc: 

D.Bennett, FHP 

J.Roberts, FHP 

R.Progar, FHP 

J.Rineholt, SNRA 

RProgar:al 
2001-2003 Pettit Lake Verbenone Trial 

Progress Report, October 2003 

BFO-PR-04-01 

To assess the ability of verbenone to deter mortal attack by the mountain pine beetle, Dendroctonus 

ponderosae on high value areas of lodgepole pine (Pinus contorta var. latifolia), FHP personnel applied 

verbenone pouches at administrative sites and summer homes located near sensitive riparian areas 

around Pettit Lake in the Sawtooth Valley in the Sawtooth National Recreation Area. 

In June 2001, 18 one-half acre rectangular (210 x 105 ft) plots were located in and around 

administrative facilities at Pettit Lake in mature lodgepole pine stands. The species and diameter at 

breast height (d.b.h.) were recorded for each plot tree. 

The verbenone formulation consisted of 98 percent technical grade, 80 percent (-), 20 percent (+) 

verbenone (4,6,6-trimethylbicyclo[3.1.1]-hept-3-en-2-one). The verbenone was formulated by and 

purchased from Phero Tech Inc., Delta, British Columbia, Canada, and applied at the rate of 40 5g 

pouches/ac. On June 14, 2001, June 12, 2002, and June 17, 2003, verbenone pouches were placed 

on the north-facing side of the same 20 trees in each of eight randomly selected plots at a height of 12 

feet and a spacing of one pouch every 32 feet or one pouch/1000 feet. The eight remaining untreated 

plots were used for comparison. During September 2001, October 2002, and September 2003, 

current-year beetle attacks were recorded and evaluated. One-way ANOVA (Sokal and Rohlf 1981) 

was used to compare the impacts of MPB on lodgepole pine between treatments. Treatments were 

considered significant at P ≤ 0.05. SAS JMP software (SAS 2001) was used for all analyses by 

ANOVA. 

Results 

Pretreatment analysis of host tree d.b.h. showed no significant difference in the number of trees within 

size class between plots receiving verbenone and those in the untreated check (Figure 1). 

Pretreatment Distribution of Lodgepole Pine at Pettit Lake 

41

6

2 2

72

42

22

3 1

16

79

8

0

10

20

30

40

50

60

70

80

90

5-7" 7.1-9" 9.1-11" 11.1-13" 13.1-15" >15"

Size Class (in.)

Avg. no. of trees / 0.5 ac.

Untreated

Verbenone

Figure 1. Average per plot density of susceptible lodgepole pine between treatments by d.b.h.
In 2001, there was little beetle activity in the Pettit Lake treatment plots with an average of two trees 

attacked per plot on the untreated plots and three trees attacked on the plots treated with verbenone 

(Figure 2). In 2002, there were an average of 8.1 (SE = 6.02) trees attacked in the untreated plots and 

3.6 (SE = 1.9) trees attacked in the plots containing verbenone. Although there were twice as many 

trees attacked in untreated plots (Figure 2), differences in between treatments were not significant (F = 

0.50; df = 1, 14; P = 0.48). In 2003, there were 8.37 (SE = 4.3) trees attacked in the untreated plots 

and 2.25 (SE = 1.58) trees attacked in the verbenone plots. However, differences between treatments 

were not significant (F = 1.78; df = 1, 14; P = 0.21). 

Average MPB Mortality at Pettit Lake Over Three Years

2

8 8

3

4

2

0

1

2

3

4

5

6

7

8

9

2001 Mortality 2002 Mortality 2003 Mortality

Year

Avg. no trees killed / 0.5 ac.

Untreated

Verbenone

Figure 2. Average number of successful MPB attacks/plot during 2000-2003. 

Mountain pine beetle is distributed unevenly among the plots at Pettit Lake. The plots on the northeast 

side of the lake had much higher densities of MPB than those on the south side of the lake among the 

summer homes. Plots on the northeast have had high mortality in all size classes of trees and those on 

the south side of the lake have little or no MPB-related mortality. Therefore, the distribution of MPBcaused mortality by size class over time is unlike the pattern observed in the plots at Little Redfish and 

Redfish Lakes where mortality first occurred in the larger diameter trees (BFO-TR-04-02). Figure 3 

shows that MPB-caused mortality occurred fairly uniformly among all size classes of trees. 
Lodgepole Attacked by MPB at Pettit Lake by Size Class After Three Years

3

7

4

2

1

2 2

2 2

1

1

1

0

1

2

3

4

5

6

7

8

5-7" 7.1-9" 9.1-11" 11.1-13" 13.1-15" >15"

Size Class (in.)

Avg. no. trees / 0.5 ac.

Untreated

Verbenone

Figure 3. Average number of trees remaining by d.b.h. size class after 4 years by treatment and d.b.h. 

Figure 4 shows the distribution of the remaining susceptible lodgepole pine by d.b.h. There are 

sufficient numbers of susceptible lodgepole remaining to continue testing the ability of verbenone to 

deter mortal attacks of lodgepole pine. I recommend that Forest Health Protection personnel continue 

to treat the same plots to determine whether verbenone can deter MPB mortality of lodgepole pine 

under conditions of increasing beetle pressure. 

Trees Remaining After Three Years

76

33

13

4

1 0

70

40

20

2 1

7

0

10

20

30

40

50

60

70

80

5-7" 7.1-9" 9.1-11" 11.1-13" 13.1-15" >15"

DBH (in.)

Trees per 0.5 ac.

Untreated

Verbenone

Figure 4. Average number of trees remaining by d.b.h. size class after 4 years by treatment and d.b.h. 
LITERATURE CITED 

Sokal, R. R., and F. J. Rolf. 1981. Biometry. W. H. Freeman and Company, New York. 859 p. 

2000-2003 REDFISH LAKE VERBENONE TRIAL Progress Report. 2003. Progar, R. A. 

BFO-TR-04-02. 17 pp. 

/s/ R.A. Progar