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 10, 2003 

Route To: 

Subject: Monitoring Biocontrol Agents in South-Central Idaho 

To: Forest Supervisors, Southern Idaho 

 

 

Due to the large burned areas created as a result of the wildfires in 2000, 2002, and 2003, the 

need for potential resources to control the spread of exotic invasive weeds into the burned areas 

is critical. In 2002 and 2003, Forest Health Protection, in cooperation with local land managers, 

monitored release sites of biocontrol insects on knapweed, leafy spurge, and Dalmatian toadflax 

to locate potential areas where biocontrol insects may be collected for release into sensitive 

burned areas where invasive species are the first colonizers. Enclosed is a report (BFO-PR-04-

03) that summarizes this monitoring effort. 

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: 

J.Roberts, FHP 

R.Progar, FHP 

D.Bennett, FHP 

C.Swearingen, Idaho City RD 

C.Johnson, R-4 

C.Haggas, North Fork RD 

T.Gionet, Middle Fork RD 

R.Vanbebber, Malad RD 

R.Mickelsen, Dubois RD 

C.Nemeth, Salmon-Challis BLM 

E.Williams, Salmon-Challis, BLM 

J.Wright, Idaho Falls, BLM 

RProgar:al 
Monitoring of Biocontrol Insect Release Sites in Southern Idaho 

2002-2003 

Report Number BFO-PR-04-03 

________________________________________________________________________ 

INTRODUCTION 

During the summers of 2002 and 

2003, members of the Forest Health 

Protection staff from the Boise Field 

Office comprising Entomologist 

Robert Progar, and seasonal 

employees Jeremy Kiser, Jennifer 

Smith, Cindy Bagness, and Owen 

Shelly in 2002 and Chad Nelson and 

Luis Lora in 2003 monitored 

locations where insects were 

released as biological control agents 

on leafy spurge (Euphorbia esula) 

and diffuse and spotted knapweed 

(Centaurea diffusa and Centaurea 

maculosa). 

These efforts were funded by the 

National Fire Plan to identify 

potential resources from which 

biocontrol insects may be collected 

for release into burned areas when 

colonized by invasive exotic weeds. 

With vast forest landscapes being 

consumed by fire in 2000 and even 

larger areas consumed in 2002 and 

2003, the need for potential 

resources to control the spread of 

exotic invasive weeds into vulnerable 

burned areas is critical. Invasive 

weeds are frequently the first plants 

to colonize disturbed areas. As 

invasive weeds become early 

occupants of available niche 

habitats, native plant species are 

prohibited from returning. The 

potential negative impacts on native 

plant species, invertebrates, and 

vertebrates are severe. Chemical 

control is cost prohibitive and 

ecologically unsound on a landscape 

scale. Hence, an effective means of 

controlling or suppressing the 

impacts of the invasion of weeds in 

burned lands after fire is to release 

biocontrol agents at the leading edge 

of invasive weed colonization. 

The release of biocontrol agents to 

reduce the vigor, competitive ability, 

and fecundity of weeds has occurred 

in Idaho since the mid-1970’s. There 

have been over 800 recorded 

releases, with most occurring on 

leafy spurge and knapweed. It is 

suspected that many more releases 

have been made but were 

unrecorded. Additionally, after initial 

release, many of the over 800 

recorded insect releases had no 

follow up and have not been 

monitored for insect establishment or 

weed impacts. 

Forest Health Protection 

Boise Field Office 
METHODS 

To assess potential resources for 

weed biocontrol in newly burned 

areas we cooperated with land 

managers involved in the biological 

control of weeds across central and 

southern Idaho (Table 1). To 

facilitate location of the release sites 

the land manager accompanied/ 

directed us to the release sites. In a 

few instances, maps and detailed 

directions were given to lead us to 

the release locations. This was 

essential because the monuments 

from the old releases are either 

missing, grown over, or otherwise 

very difficult to locate. The use of 

GPS is essential in locating many of 

the sites. However, most of the 

releases we were searching for 

occurred before global positioning 

systems were commonly used. We 

focused our efforts on surveying 

Table 1. Cooperators in the 2002 and/or 2003 monitoring of biological control 

insect releases on leafy spurge and knapweed. 

Cooperator Agency 

Craig Nemeth Salmon-Challis BLM 

Elias Williams Salmon-Challis BLM 

Chris Tambe Salmon-Challis BLM 

Cindy Haggas USDA–FS North Fork Ranger District 

Tommy Gionet USDA-FS Middle Fork ranger District 

Rick Vanbebber USDA-FS Malad Ranger District 

Holger Jensen USDA-FS Mackay Ranger District 

Jim Hawkins Custer County Extension Service 

Earl Skeen Custer County Extension Service 

Chad Cheny Butte County Extension Service 

Robert Mickelsen USDA-FS DuBois Ranger District 

Jason Wright Idaho Falls BLM 

Charlie Swearingen USDA-FS Idaho City Ranger District 

Steve Spafford USDA-FS Emmett Ranger District 

Deb Taylor USDA-FS Ketchum and Fairfield 

Ranger Districts 

John Shelly USDA-FS Fairfield Ranger District 
sites that had biocontrol agents 

released at least 4 years ago, 

allowing time for insects to become 

established and to multiply. 

We monitored 82 release sites 

during 2002. Thirty-five of these 

were infestations of leafy spurge and 

47 sites were knapweed infestations. 

We also monitored five sites where 

introductions of a new insect 

(Mecinus janthinus) on Dalmatian 

toadflax in a cooperative effort with 

the University of Idaho. 

In 2003, we monitored 85 release 

sites. Fifty-five of the sites occurred 

in knapweed infestations, 14 in leafy 

spurge, 5 in Dalmation toadflax, and 

11 in areas of rush skeleton weed. 

Sweep netting was the primary 

means used to sample for biocontrol 

insects. This method is very 

effective for sampling/collecting 

Larinus sp. on knapweed and, 

Aphthona sp. flea beetles, and 

Oberea beetles on leafy spurge. It is 

not very efficient in sampling 

Agapeta zoegana moths or 

Cyphocleonus weevils on knapweed. 

A standard protocol (Appendix 1) 

was used as a monitoring tool to 

gathered abiotic information about 

the release site, information on the 

density of the target weed and data 

on the target biocontrol insect. It 

was adequate in many respects for 

collecting the desired information, 

however, there are several 

modifications recommended for 

future monitoring efforts: 

 1. On sites where multiple 

releases were made of different 

biocontrol agents, the monitoring 

form should be able to accommodate 

more than one target insect. 

 2. There should be an entry on 

the form for an estimated size of the 

area containing weeds. 

 3. There should be an entry for 

the initial date of release so the 

length of time that the insects had to 

establish may be determined. 

 4. There should be criteria 

oriented as a checklist as noted by 

Sturdevant and Dewey (2002) that 

can assess whether the sites 

monitored would make a good 

insectory. There also needs to be 

space set aside for the addition of 

anecdotal information relative to 

site/weed/insect characteristics. 

Attached (Appendix 1) is a 

recommended form for use in 

monitoring release sites. 

Leafy Spurge 

Among the releases monitored on 

leafy spurge in 2002, three sites had 

collectable populations of Oberea

and eight had collectable populations 

of Aphthona sp. flea beetles. The 

majority of the sites had either 

“established” or detectable levels of 

insects termed “present”. However, 

since we were targeting “older” 

releases, many of the leafy spurge 

release sites we visited had 

significantly reduced weed 

populations. The weed was present 

in small-dispersed patches rather 

than a large contiguous monoculture. 

In the presence of Aphthona flea 

beetles, insect feeding frequently 

causes uneven patterns in the 

distribution of leafy spurge. The 

effects of Aphthona sp. beetle 
feeding on leafy spurge are 

commonly exhibited as a gradation 

in the density and vigor of weeds 

away from the point of release, 

frequently referred to as a “bomb 

blast”. When insect populations are 

high, the leading edge of insect 

feeding is commonly characterized 

by large numbers of adult beetles 

feeding on individual plants with 

many plants infested with beetles. 

Over time, Aphthona beetles are 

capable of significantly reducing a 

population of leafy spurge, however, 

the weed is not eliminated, but 

commonly returns in a patchy 

distribution of plants exhibiting low 

vigor because of feeding pressure 

exerted by the beetle. Therefore, at 

older release sites, beetles are 

present, but usually not in outbreak 

numbers. 

It should also be noted that the 

abundance of beetles vary within the 

patch of weeds. As the leading edge 

of the initial insect “bomb blast” 

expands away from the point of 

release, the plants containing large 

numbers of insects are located 

further from the location where the 

release was made. Frequently, the 

entire area infested with weeds had 

to be searched to locate a 

collectable population of insects. 

Aphthona populations vary with 

season. In south/central Idaho, the 

population usually peaks in early- to 

mid-June. Because there were so 

many sites to visit, we were 

monitoring for Aphthona through the 

end of August when populations 

were severely declined. 

In one area, we monitored three 

leafy spurge sites found to have 

collectable populations of Oberea 

erythrocephala, a stem and root 

boring beetle. This beetle is able to 

kill leafy spurge over large areas. 

Eggs are laid in niches at the upper 

portion of the stem. In the larval 

stage, the insect bores down the 

stem to the root crown. In the 

process of egg laying and larval 

tunneling, the top of the plant is killed 

preventing formation of seeds. The 

larva overwinters in the root crown 

consuming most of the tissue in the 

root crown by the time it is fully 

developed. Apparently, 2 years are 

required for the adult to develop in 

North America. This insect is 

especially beneficial because it 

prevents seed formation and kills the 

plant by consuming root tissues. 

In the 14 leafy spurge release sites 

we monitored in 2003, we found 

detectable populations at 4 sites, no 

biocontrol insects at 2 sites, and 

collectable populations at 8 sites. 

Knapweed 

Among the 47 knapweed sites we 

monitored in 2002, four were found 

to have collectable populations of 

Larinus minutus and one with 

collectable populations of 

Cyphocleonus achates. Nearly all of 

the sites had Larinus minutus

present and established, however, 

most of the sites did not have 

collectable populations. A seedhead 

feeder, a single Larinus larva can 

destroy an entire seedhead. 

Cyphocleonus achates is a large root 

feeding weevil that can render 

considerable damage to knapweed 

plants (Rees et al.1996). We made 

observations at some sites of nearly 

20 larvae feeding on a single plant 
with nearly every plant having 

infested roots. Nine of 47 knapweed 

sites we visited had releases of 

Cyphocleonus. We collected weevils 

at few of these sites, however, 

because sweep netting is not the 

best means of surveying for the 

presence of Cyphocleonus. 

In 2003 we found collectable 

populations of Larinus minutus at 

nine locations and collectable 

populations of Cyphocleonus at the 

same location as in 2002. Twenty 

seven sites had established 

populations where Larinus was 

present and no biocontrol insects 

were found at 19 locations 

Rush Skeleton Weed 

In 2003, we assisted the Middle Fork 

Ranger District at the Salmon-Challis 

National Forest by surveying for the 

establishment of the rust fungus 

(Puccinia chondrillina), skeleton 

weed gall mite (Eriophyes 

chondrillae), and (the skeleton weed 

gall midge (Cystiphora schmidti) on 

rush skeleton weed. The biocontrol 

agents were in collectable numbers 

at one location, present and 

established at six sites, and not 

found at four release sites. 

General Observations

During the course of the 2002 and 

2003 seasons, we cooperated with 

15-20 different land managers 

across central and southern Idaho. 

The amount of active management 

using biocontrol to manage invasive 

weeds varied from little to a very 

strong program based primarily on 

biocontrol insects. Those land 

managers who actively managed the 

biocontrol insects had less severe 

weed infestations than those who 

either relied primarily on chemical 

control or those who simply released 

the insects and assumed that nature 

would take its course and the insects 

would eliminate the weeds. The 

most effective managers would 

closely monitor their previous 

release sites and upon emergence, 

would collect and move the insects 

to new infestations on areas where 

there were lower insect populations. 

These managers were 

supplementing existing populations 

with additional releases of additional 

insects of the same species and 

adding new species of biocontrol 

insects that attack the plant in a 

different point. 

References 

REES, N.E., QUIMBY, P.C. JR., 

PIPER, G.L., COOMBS, E.M., 

TURNER, C.E., SPENCER, N.R., 

AND L.V. KNUTSON. 1996. 

BIOLOGICAL CONTROL OF 

WEEDS IN THE WEST. WESTERN 

SOCIETY OF WEED SCIENCE. 

BOZEMAN, MONTANA. 

STURDEVANT, N.J. AND J. 

DEWEY. 2002 EVALUATING 

RELEASES OF CYPHOCLEONUS 

ACHATES AND AGAPETA 

ZOEGANA AS POTENTIAL FIELD 

INSECTARIES AND EFFECTS OF 

WILDFIRE ON PREVIOUS 

RELEASES. FOREST HEALTH 

PROTECTION REPORT 02-6 JULY 

2002. 
BIOLOGICAL CONTROL MONITORING REPORT ===================================================================================== 

SITE INFORMATION 

Monitored By: __________________________ Release Date: _____/____/____ Monitor Date:____/____/_______ (yyyy mm dd) 

State: ____ County: _________________ Target Agents: 1.)_____________2.)_____________3.)______________

Target Weed: _______________________ Size of Infested Area (acres) : _________ Ease of Access: ___________ 

Other Agents Present:_______________________________________________________ 

Land Ownership: BIA BLM CGOV OTH PVLA STAT TNC TRIB USFS USFW USOT 

Local Ownership (Optional): ______________________________________________(Assign a Site Name) 

UTM: UTM Datum Zone: _ _ UTM Year: _ _ _ _ UTM Easting: _ _ _ _ _ _ _ _ UTM Northing: _ _ _ _ _ _ _ _ 

Lat: Deg ________ Min ________ Sec ________ Long: Deg ________ Min ________ Sec ________ 

LL Datum: ______________________________________________________________________________________ 

Legal: T ________ R ________ Sec ________ Q ________ QQ ________ 

======================================================================================

MONITORING INFORMATION 

Sampling Time: _______________ 

Weather Conditions: Clear ____ Partly cloudy ____ Overcast ____ Rain ____ Other (specify) ________ 

Air Temperature (F): <60 ____ 60-70 ____ 70-80 ____ 80-90 ____ >90 ____ Actual Temp. _______

Wind: Calm ____ Light ____ Moderate ____ Strong ____ Gusty ____

===================================================================================== 

BIOLOGICAL CONTROL MONITORING 

Visual Observation of any Biocontrol Agent Before Sampling? Yes ____ No ____

Visual Observation of Biocontrol Agent/5 Minutes: Species ______________________________ Number ______ 

Seed Head Sampling: Number Sampled _____ Total Number Infested _____ Species _______________________

Agent Sweeping: Number of Sweeps _____ Total Number of Agents Swept _____ Species ___________________ 

Root Sampling: Number of Roots Sampled _____ Total Number Infested _____ Species _____________________

Estimate of Population Level: None _____ Present _____ Established _____ Marginally Collectable _____ 

 Collectible _____ 

*Answer the above questions for each biocontrol organism found present on site and attach. 

===================================================================================== 

VEGETATION MONITORING 

Photos Taken? Yes _____ No _____

Dominant Plant: _____________________________ 

Percent Canopy Cover: Tree ____ Shrub ____ Forb ____ Grass ____ Litter ____ 

Type of Sample: Daubenmire Frame _____ Other (specify) ____________________________________

Average Number of Target Weed Stems: ________ 

Average Height of Target Weed: ________ 

Average Percent Canopy Cover of Target Weed: ________ 

Enter general observations on back of page. 
MONITORING INSTRUCTIONS 

Visual Observation: Sit quietly for 5 minutes in the infested area near the release point and look for the insects. If you 

see none, then carefully and slowly move the plants aside to look under the leaves and on the stems. Record 

observations on monitoring worksheet. Summarize results onto page 1. 

 

Seedhead Sampling: Lorinus spp. Within a 15-meter circle surrounding the release point collect 200 seedheads. 

Dissect the seedheads and examine for the presence of a biocontrol agent. Record on the worksheet if the seedhead is 

infested, the species and number of biocontrol agents present. Summarize the results onto page 1. 

*If 50 percent of the seedheads are infested then the population is likely collectible. 

Agent Sweeping: Lorinus or Spurge/Aphthona spp. First, look over the release area to see if biocontrol agents are 

visually apparent. Next, sweep five sampling points along four lines in N, S, E, and W direction from the release point 

(20 points total). For each line, begin 1 meter from the release point. Using a 15-inch diameter net, make four sweeps 

(two to right center, two to left center). Carefully examine the net and count and identify species of the biocontrol 

agents present, then empty the net behind you. Record on worksheet. Move 2 meters out and repeat above steps. 

Continue until five points have been sampled, then repeat over the remaining cardinal directions. Record on monitoring 

worksheet. Summarize all transect results on page 1. 

*If you collect two target organisms per sweep or a total of 160 then the population is likely collectible. 

Root Sampling: Chyphocleonus/Agapets/Sphenoptera Within a 15-meter circle surrounding the release point, dig 

roots from 20 randomly selected plants. Select plants with a root crown diameter of atleast 12 millimeters. Dissection of 

the roots should be done in the field for best results. If this is not possible, place the plants on ice or in a cool place for 

dissection later. Count the number of infested plants. Record on monitoring worksheet. Summarize results onto page 1. 

*If 25 percent or more of the plants are infested; the population is likely collectable. 

Vegetation Monitoring: Establish four transects, in each cardinal direction, from the release point. Place a Daubenmire 

frame to the right side of each transect line at a point 1, 3, 5, 7, and 9 meters. Within each frame, count the number of 

stems, record the average height and the percent canopy cover for the target weed. Record on monitoring worksheet and 

summarize the results onto page 1. 
MONITORING WORKSHEET 

VISUAL OBSERVATION (5 minutes)

SEED HEAD SAMPLING (Record species and number found. If seedhead is empty, leave blank). 

Seed Head # Species #Found Seed Head# Species #Found Seed Head# Species #Found 

 1 68 135 

 2 69 136 

 3 70 137 

 4 71 138 

 5 72 139 

 6 73 140 

 7 74 141 

 8 75 142 

 9 76 143 

 10 77 144 

 11 78 145 

 12 79 146 

 13 80 147 

 14 81 148 

 15 82 149 

 16 83 150 

 17 84 151 

 18 85 152 

 19 86 153 

 20 87 154 

 21 88 155 

 22 89 156 

 23 90 157 

 24 91 158 

 25 92 159 

 26 93 160 

 27 94 161 

 28 95 162 

 29 96 163 

 30 97 164 

 31 98 165 

 32 99 166 

 33 100 167 

 34 101 168 

 35 102 169 

 36 103 170 

 37 104 171 

 38 105 172 

 39 106 173 

 40 107 174 

 41 108 175 

 42 109 176 

 43 110 177 

 44 111 178 

 45 112 179 

 46 113 180 

 47 114 181 

 48 115 182 

 49 116 183 

 50 117 184 

 51 118 185 

 52 119 186 

 53 120 187 

 54 121 188 

 55 122 189 

 56 123 190 

 57 124 191 

 58 125 192 

 59 126 193 

 60 127 194 

 61 128 195 

 62 129 196 

 63 130 197 

 64 131 198 

 65 132 199 

 66 133 200 

 67 134 
AGENT SWEEPING (4 sweeps at each of the 5 points per transect = 20 sweeps per transect. 4 transects x 20 sweeps 

per transect = 80 sweeps per release site).

 Distance From Release Point N E S W 

 1 meter 

 3 meters 

 5 meters 

 7 meters 

 9 meters 

====================================================================================== 

ROOT SAMPLING (Samples should be taken within a 15-meter circle surrounding the release point). 

 Root Number Species of Larva Number of Larva 

 1 

 2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 

 10 

 11 

 12 

 13 

 14 

 15 

 16 

 17 

 18 

 19 

 20 

 *Record: AG for Agapeta, CY for Cyphlocleonus or SP for Sphenoptera. 

 ===================================================================================== 

VEGETATION MONITORING (Sample should be taken on the right side of transect with back to release point 

facing in the appropriate cardinal direction. Record Number of Stems, Average Height and Percent Cover at 1, 3, 5, 7 

and 9 meters from the Release Point). 

Distance From Release Point N E S W 

 Number of Stems 

 1 meter Average Height 

 Percent Cover 

 Number of Stems 

 3 meters Average Height 

 Percent Cover 

 Number of Stems 

 5 meters Average Height 

 Percent Cover 

 Number of Stems 

 7 meters Average Height 

 Percent Cover 

 Number of Stems 

 9 meters Average Height 

 Percent Cover 
BIOLOGICAL CONTROL MONITORING REPORT GUIDE 

Monitored By: Enter the full name (last, first, MI) of the primary individual doing the monitoring. 

Release Date: Enter the date the initial release was made. 

Monitor Date: Enter the date the monitoring is conducted in the following format – YYYY/MM/DD. 

State: Enter the two-digit standard postal code abbreviation for the state where the biocontrol monitoring is conducted. 

EXAMPLE – Monitoring is conducted in Idaho, you would record; ID. 

County: Enter the county where the monitoring is being done. 

Target Agent: The scientific name (genus and species) of the agent(s) being monitored. 

Target Weed: The scientific name (genus and species) or the common name of the target weed the agents were released 

to control. 

Size of Area Infested: The estimated size of the area infested with weeds. 

Ease of Access: One-word definition on how easy it is to locate and access the location. 

Other Agents Present: The scientific name (genus and species) of other biocontrol agents released at the site. 

Land Ownership: The ownership of the land where the monitoring is being done. 

CODE DESCRIPTION CODE DESCRIPTION

STAT State Lands TNC The Nature Conservancy 

BLM Bureau of Land Management TRIB Tribal Lands 

CGOV County Government USFS United States Forest Service 

OTH Other USFW United States Fish and Wildlife Service 

PVLA Private Landowner USOT US Government (other federal lands) 

Local Ownership: This field identifies state and local land managers/owners. Record a site name. 

UTM or Lat/Long or Legal: On the ground point of monitoring. Locations can be described using a variety of 

methods; any one of the following methods may be used; UTMs, Lat-Longs, or legal. 

UTM: UTM Datum Zone and year, with the easting and northing localities. 

Lat/Long: Degrees, minutes, and seconds. 

 

LL Datum: The suggested set-up for your GPS is as follows. Set the Position Format to hddd mm’ss.s. Set the Map 

Datum to NAD83. Set the Units to Statute Miles. Set the North Reference to True North. This is not a required set-up, 

but if you use something different, you need to describe it here so the exact position can be plotted on a GIS layer. 

Legal: Township, Range, section, quarter section and quarter/quarter section. 

MONITORING INFORMATION 

Sampling Time: Time of day the monitoring is being done. 

Weather Conditions: Weather conditions at the time and place the monitoring is being done. Check one of the 

following; clear, partly cloudy, overcast, rain or other. 

Air Temperature (F): Estimate, or measure, the temperature (degrees Fahrenheit) when the monitoring is being done.

Wind: Estimate the wind speed when monitoring. Check one of the following; calm, light, moderate, strong or gusty.
BIOLOGICAL CONTROL MONITORING 

Visual Observation of any Biocontrol Agent Before Sampling: Before conducting any type of monitoring, make a 

quick visual inspection around the release site for any biocontrol agents. Check Yes if any are observed, No if nothing is 

found. 

Visual Observation of Biocontrol Agent/5Minutes: Complete the Visual Observation procedure described in the 

Monitoring Instructions. Record species and number observed. 

 

Seed Head Sampling: Complete the Seed Head Sampling procedure described in the Monitoring Instructions. Record 

the total number of seed heads sampled, total number of seed heads infested and the species of biocontrol agent found. 

Agent Sweeping: Complete the Agent Sampling procedure described in the Monitoring Instructions. Record total 

number of sweeps, total number of agents swept and species found. 

Root Sampling: Complete the Root Sampling procedure described in the Monitoring Instructions. Record total number 

of roots sampled, total number infested and species found. 

Estimate of Population Level: Follow the recommendations in the Monitoring Instructions and check none, present, 

established, marginally collectible or collectible. 

VEGETATION MONITORING 

Photos Taken: If photographs are being taken as part of the monitoring effort check Yes. If not check No. 

Dominant Plant: Estimate and record the dominant plant in the general area around the release site. 

Percent Canopy Cover: Estimate and record the percent canopy cover for the vegetation in the general area around the 

release site. Canopy cover is the percent of the ground shaded by vegetation. EXAMPLE – A grass plant is not 

completely shading the ground below it and gaps occur between the shaded portions. Canopy cover is assessed for the 

top layer of vegetation only. EXAMPLE – If a leafy spurge plant is growing over a grass plant and the grass cannot be 

seen when looking directly down, only the leafy spurge canopy cover is counted. The total canopy cover possible is 100 

percent. 

Type of Sample: Check Daubenmire Frame is one was used for vegetation monitoring. It is the preferred type of frame 

for vegetation monitoring. Specify the type and size of frame if a different one is used. A Daubenmire Frame is 1/10 

square meter. It is a rectangle that measures 20 by 50 centimeters. They can be constructed out of 1-inch PVC pipe for 

less than $2. A three-sided Daubenmire Frame can be used for sampling when the vegetation is so tall it is difficult to 

place the frame accurately. 

Average Number of Target Weed Stems: Record the average number of target weed stems per plot. Sum the total 

number of target weed stems recorded on the worksheet for the 20 vegetation monitoring points taken at each monitoring 

site and divide by 20. 

Average Height of Target Weed: Record the average height of the target weed per plot. Sum the average heights 

recorded for the 20 vegetation monitoring points taken at each monitoring site and divide by 20. 

Average Percent Canopy Cover of Target Weed: Record the average percent canopy cover of the target weed per 

plot. Sum the percent canopy covers recorded on the worksheet for the 20 vegetation monitoring points and divide by 

20.