Biological Control of Spotted Knapweed and Canada Thistle at The Fort Carson Military Reservation, Ft. Carson, Colorado

1997 Progress Report

Submitted to the Directorate of Environmental Compliance and Management, Ft. Carson, Colorado

Original photo by R.D. Richard G. J. Michels, Jr., D. A. Fritts, and J. B. Bible The Texas Agricultural Experiment Station P.O. Box 10, Bushland, TX 79012 BIOLOGICAL CONTROL OF SPOTTED KNAPWEED AND CANADA THISTLE AT THE FORT CARSON MILITARY RESERVATION, FT. CARSON, COLORADO

1997 PROGRESS REPORT

by

G. J. Michels, Jr., D. A. Fritts, and J. B. Bible

submitted to the United States Army, Directorate of Environmental Compliance and Management, Ft. Carson, Colorado

Introduction The goal of the biological control of weeds program is to reduce the existing populations and control the spread of selected state- and federal-listed noxious weeds at two military installations located on the Front Range of the Rocky Mountains in Eastern Colorado. The two sites are, the Fort Carson Military Reservation (FCMR) at Colorado Springs, CO and the Pinon Canyon Maneuver Site (PCMS) at Trinidad, CO. In the initial program, spotted knapweed, maculosa Lam., and Canada thistle, (L.) Scop., will be the target species. The objectives of the research are to 1. Develop and implement procedures and sampling methods to assess the present state of any existing biological controls on the selected species at FCMR and/or PCMS; 2. Monitor abiotic and biotic factors which may be peculiar to FCMR and/or the PCMS through field data collection and release-site weather stations. Assess the impact of these factors on establishment of natural enemies; 3. Conduct greenhouse studies to determine the interaction of several available natural enemies of the selected weed species with each other and their combined effect on the plant, and conduct herbicide/natural enemy compatibility tests to help make decisions for IPM strategies. Use the greenhouse populations of the natural enemies for additional releases; 4. Release several species of natural enemies in field trials using release cages and open field releases to compare survival and establishment over a period of at least three years. Monitor and redistribute established populations.

Knapweed is an aggressive annual weed, has little nutritive value and is an invasive competitor, decreasing forage production as much as 60 to 90 percent. Spotted knapweed is one of the most important rangeland weeds in western North America with approximately 287 million ha infested.

Canada thistle is an aggressive dioecious perennial, which grows in patches and has a diverse habitat. Because of its random distribution, it is difficult to determine complete losses, but is considered to be a noxious weed in at least 34 states in the United States.

This report describes the progress during 1997 and early 1998. Several organizations have cooperated with this project, including the Colorado Department of Agriculture, Pennsylvania Department of Agriculture, Forestry Sciences Laboratory at Montana State University and USDA-APHIS at Montana State University.

Chronology

April In cooperation with Mrs. Robin Romero, United States Fish and Wildlife Service at Fort Carson, Mr. James Kulbeth, Directorate of Environmental Compliance and Management, and Mr. Fred Stahl, Colorado Department of Agriculture, release sites were located. One spotted knapweed site was located near Turkey Creek. Two Canada thistle sites were located, and designated as ARA and Reservoir. The surrounding areas were surveyed for vegetation species. Spotted knapweed seed heads were collected to determine if were currently present. The knapweed seedhead , quadrifasciata (Meigen), was found in the collection. Two cages, fabricated of Lumite® screen mesh over 4’ x 6’ x 6’ high steel square tubing frames, were erected at each site except Turkey Creek. The netting for one cage needed repair and was placed at a future date. A weather station was placed at the ARA site.

May A second spotted knapweed site was located in the Cantonment area, designated as Cantonment I, and two cages were erected. The netting was placed on the second cage at the Turkey creek site. Project signs reading, “Biological Control of Noxious Weeds, Please Do Not Disturb, A Cooperative Research Program: DECAM, The Texas Agricultural Experiment Station, The Colorado Department of Agriculture,” were placed at Turkey Creek, Cantonment I, ARA, and Reservoir (Fig. 1).

June Adult lesser knapweed flower weevils, Larinus minutus Gyll., were field collected at two sites near E. Helena, MT, with the assistance of Mr. Ronald Lang, USDA-APHIS on June 2, 1997. At the first site approximately 3400 insects were collected. Most of these insects were collected from about 17 diffuse knapweed plants (Fig. 2). Mr. Lang stated releases were made at this site in 1993 and this could be the last year for collections since L. minutus had eliminated the diffuse knapweed infestation. Weevil numbers were much lower at the second site. The weevils were sorted and place into individual containers.

On June 3, 1997 nine spotted knapweed bouquets containing the banded gallfly, Urophora affinis Frauenfeld, were collected near the Jefferson River. This site was approximately 5 miles west of Three Forks, MT, and 65 to 70 miles southeast of E. Helena, MT. Each bouquet contained approximately 1200 larvae.

Field releases were made on June 5, 1997 at the Turkey Creek and Cantonment I sites. At each site, 30 to 50 L. minutus were released into one established cage and 50 to 70 released on uncaged plants. A total of 100 insects were released at each site (Table 1). A flag was placed at each open field point of release.

Figure 1. Outdoor cage and project sign at Cantonment I release site. Summer, 1997.

Figure 2. Larinus minutus feeding on diffuse knapweed at East Helena, MT. June 1997.

Table 1. Summary of Insects Released for Biological Control of Canada Thistle and Spotted Knapweed at Ft. Carson, CO, 1997-1998. Common name Species Source Agency Release Notes Date Site1 Number Total Caged Open Canada thistle (Cirsium arvense ) Thistle-feeding shield beetle Cassida rubiginosa Harrisburg, PA Penn. Dept. of Agric. 07/03/1997 4 25 0 25 Canada thistle bud weevil Larinus planus Harrisburg, PA Penn. Dept. of Agric. 07/03/1997 3 47 0 47 Thistle stem gall fly Urophora cardui LaGrande, OR Forestry Sci Lab 01/28/1998 6 0 77 539 3 Thistle stem gall fly Urophora cardui LaGrande, OR Forestry Sci Lab 01/28/1998 7 0 92 644 3 Spotted knapweed (Centaurea maculosa ) Knapweed peacock fly Chaetorellia acrolophi Palisade, CO Colo. Dept. of Agric. 07/02/1998 2 250 250 500 Knapweed root weevil Cyphocleonus achaetes Palisade, CO Colo. Dept. of Agric. 08/06/1997 5 50 200 250 Lesser knapweed flower weevil Larinus minutus Helena, MT USDA/APHIS 06/05/1997 1 30-50 50-70 100 4 Lesser knapweed flower weevil Larinus minutus Helena, MT USDA/APHIS 06/05/1997 2 30-50 50-70 100 4 Spotted knapweed seed head paucipunctella Spokane, OR USDA/APHIS 04/28/1998 6 2 0 3456 5 Spotted knapweed seed head moth Metzneria paucipunctella Spokane, OR USDA/APHIS 04/28/1998 7 2 0 3456 5 Spotted knapweed seed head moth Metzneria paucipunctella Spokane, OR USDA/APHIS 04/28/1998 1 0 1728 5,6 Banded gall fly Urophora affinis Three Forks, MT USDA/APHIS 06/05/1997 1 1 3 4800 2,4 Banded gall fly Urophora affinis Three Forks, MT USDA/APHIS 06/05/1997 2 1 3 4800 2,4 Knapweed seed head fly Urophora quadrifasciata determined to be previously established at Turkey Creek site 1 Sites: 1 - Cantonment I; 2 - Turkey Creek; 3 - ARA; 4 - Resevoir; 5 - Cantonment II, 6 - Outdoor Recreation, 7 - Duck Pond. 2 Released in bouquets of dead spotted knapweed with approximately 1200 larvae/bouquet. 3 Released in galls, approximately 7 larvae/gall. Releases were made in small screened boxes to prevent rodent predation. 4 Recovered on 7/2/98. 5 Released in screened boxes containing infested seedheads; 2,400 seedheads/box, approx. 1728 larvae per box (72% infestation). 6 Released at HazMaterials Site which was accidentally mowed at a later date, then abandoned.

Two cages were established at Turkey Creek and Cantonment I sites so that complimentary releases could be made. Bundles of spotted knapweed plants containing an estimated 3600 open and 1200 caged U. affinis larvae were introduced (Table 1, Fig. 3).

July Larinus planus (F.), the Canada thistle bud weevil, and a thistle-feeding shield beetle, Cassida rubiginosa Müller, were field collected on July 2, 1997 by Mr. Jim Stimmel, Pennsylvania Department of Agriculture, Harrisburg, PA, for release on Canada thistle. One half of the collection was shipped to Fred Stahl, Colorado Department of Agriculture, Palisade, CO, while the other half was shipped to Fort Carson Military Reservation for the purpose of monitoring establishment and population increases. On July 3, 1997 25 adult C. rubiginosa were released into one cage at the Reservoir site and approximately 47 adult L. planus were released into one cage at the ARA site (Table 1). Due to low collection numbers, no open releases were made at either site.

August On August 6, 1997 a second spotted knapweed release site was located in the Cantonment and designated as Cantonment II. One caged and four open field releases of adult knapweed root weevils, Cyphocleonus achaetes (Fahr.), were made (Table 1). Fifty beetles were released at each site. The beetles were provided by Fred Stahl, Colorado Department of Agriculture, Palisade, CO.

On August 27, 1997 plant height and density were recorded at Cantonment I, Cantonment II, Reservoir, and ARA sites (Tables 2 and 3, Figs. 4, 5, 6 and 7). Cage screens were removed from frames at release sites except for Cantonment II containing C. achaetes since they were newly-released. Cages were not removed and data for plant height and density were not recorded at Turkey Creek due to recent rains, which made the road impassable.

September Plant height and density were recorded at Turkey Creek on September 5, 1997 (Table 3, Figs. 8, 9, and 10). The cage screen was removed from the frame where L. minutus had been released, but was not removed from the frame where U. affinis had been placed to prevent feeding on knapweed seedheads by deer.

January, 1998 Galls containing larvae of the thistle stem gallfly, Urophora cardui (L.), larvae were field collected on October 15, 1997 by Dr. George Markin, Forestry Sciences Laboratory, Montana State University for release on Canada thistle. Two new Canada thistle release sites were located at Fort Carson, and designated as Outdoor Recreation (Figs. 11 and 12) and Duck Pond sites. Three cages containing the U. cardui galls were placed at each site on January 28, 1997 (Table 1). The cages were constructed of 1”x 4” wood forming a 12” – square box frame, with the bottom and top covered with ¼” galvanized metal screen to prevent rodent predation. Plant height and density were recorded at 10, 20 and 30-m intervals where possible (Tables 4 and 5). Figure 3. Spotted knapweed bouquet infested with Urophora affinis larvae. E. Helena, MT, June, 1997.

Figure 4. Mature spotted knapweed at Cantonment II release site. August, 1997. Figure 5. Canada thistle plants after cage screen has been removed at ARA release site. September, 1997.

Figure 6. Mature Canada thistle infestation at Reservoir release site. September, 1997. Figure 7. Canada thistle infestation located in drainage area at Reservoir release site. September, 1997.

Figure 8. Mature spotted knapweed infestation at Turkey Creek release site. September, 1997. Figure 9. Spotted knapweed infestation with release cage and project sign at Turkey Creek release site. September, 1997.

Figure 10. Spotted knapweed infestation at Turkey Creek release site showing typical robust growth. September, 1997. Figure 11. Canada thistle infestation at Outdoor Recreation release site in January , 1998, with small release cage for Urophora cardui.

Figure 14. Close up photo of Urophora cardui release cage at Outdoor Recreation release site, January, 1998. Table 2: Canada Thistle Plant Height and Density, Ft. Carson, CO, August 1997. Plant Plant height (cm) Plant/m2 Plant height (cm) Plant/m2 No. Cage Open Open Cage Open Cage Open Open Cage Open Site: ARA Southeast area Northwest area 1 152 121 113 38 28 138 125 88 42 28 2 136 58 118 30 98 109 77 24 3 137 39 71 18 159 112 78 22 4 72 87 128 24 157 94 87 30 5 79 105 111 20 81 103 107 26 6 132 118 60 26 142 116 110 24 7 105 104 95 16 161 84 98 18 8 131 116 43 18 47 114 114 20 9 83 66 110 26 118 119 118 34 10 117 112 101 24 127 61 58 26

Avg. 114.4 92.6 95 38 23 122.8 103.7 93.5 42 25.2

Site: Reservoir South area North area 1 115 100 84 24 38 110 72 80 34 40 2 110 77 78 46 83 65 76 52 3 76 91 71 34 788673 32 4 103 73 101 40 111 90 96 48 5 88 98 100 58 88 69 94 60 6948296 329772103 34 7 101 63 87 44 44 61 97 42 8 98 74 47 38 589995 44 9 109 96 66 48 86 81 38 54 10 72 88 94 36 67 61 70 38

Avg. 96.6 84.2 82.4 24 41.4 82.2 75.6 82.2 34 44.4

Table 3: Spotted Knapweed Plant Height and Density, Ft. Carson, CO, August 1997. Plant Plant height (cm) Plant/m2 Plant height (cm) Plant/m2 No. Cage Open Open Open Open Cage Open Cage Open Open Open Open Cage Open

Site: Cantonment II Northeast area South area 1 34 100 31 91 88 54 60 35 35 45 98 52 2 275479 6673 48 28915645 60 3 409769 7586 54 90897279 52 4 426842 2991 34 44788486 40 5 367774 3837 38 82756777 48 6 329276 4862 44 37648949 34 7 339154 9357 46 56899251 38 8 414448 8671 54 63463544 52 9 243861 8294 62 70684883 46 10 37 41 68 79 61 52 63 90 62 67 62

Avg. 34.60 70.20 60.20 68.70 72.00 54.00 49.20 56.80 72.50 65.00 67.90 48.40

Site: Cantonment I West area East area 1 121 49 119 82 74 133 63 56 72 66 2 132 67 97 56 32 37 93 62 3 96 61 89 44 119 62 78 54 4 123 59 71 66 71 54 87 38 5 112 72 38 80 56 76 83 46 6 8790 54 54 638990 56 7 9495 63 58 989172 52 8 110 76 76 34 70 58 68 40 9 102 84 93 42 95 77 51 36 10 76 98 110 54 58 93 82 50

Avg. 105.30 75.10 81.00 82.00 56.20 79.50 70.00 76.00 72.00 50.00

Site: Turkey Creek West area East area 1 135 79 114 30 24 74 97 53 38 28 2 79 53 104 10 94 74 81 36 3 86 64 137 32 69 69 51 42 4 112 97 104 12 58 104 53 34 5 71 102 90 56 81 58 69 40 6 86 102 61 42 69 74 30 42 7 74 124 76 30 122 79 81 46 8 8464 94 18 916966 34 9 9471 46 20 536681 30 10 91 53 74 22 46 53 53 36

Avg. 91.20 80.90 90.00 30.00 26.60 75.70 74.30 61.80 38.00 36.80

Table 4. Canada Thistle Plant Height at Urophora cardui Release Sites, Ft. Carson, CO, January 1998. Plant No. Plant Height (cm) at indicated meters from release point 10m 20m 30m 10m 20m

Site: Duck Pond Site: Outdoor Recreation Point of Release 1 125 168 99 120 92 87 2 92 105 94 69 80 108 3 96 158 110 52 72 102 4 98 110 111 79 81 103 5 110 108 128 80 77 98 Avg. 104.20 129.80 108.40 80.00 80.40 99.60 North 1 72 106 73 71 62 86 81 2 839158 68 84 9082 3 927275 52 70 8379 4 838376 63 80 7885 5 807960 31 74 7686 Avg. 82.00 86.20 68.40 57.00 74.00 82.60 82.60 South 1 74 72 114 41 22 2 63 84 109 38 18 3 88 81 101 22 56 4 100 85 110 30 49 5 70 91 112 15 41 Avg. 79 82.60 109.20 29.20 37.20 East 1 82 131 71 118 78 72 88 2 111 135 32 110 69 71 64 3 83 58 33 107 69 61 75 4 89 93 62 119 74 68 79 5 86 96 41 128 73 74 93 Avg. 90.20 102.60 47.80 116.40 72.60 69.20 79.80 West 1 105 125 115 98 68 94 76 87 52 2 80 110 101 110 84 102 71 78 62 3 89 120 96 92 109 98 83 69 57 4 56 118 82 106 118 102 92 99 50 5 101 123 118 105 85 97 81 91 64 Avg. 86.20 119.20 102.40 102.20 92.80 98.60 80.60 84.80 57.00

Table 5. Canada Thistle Plant Density at Urophora cardui Release Sites, Ft. Carson, CO, January 1998. Location Plants/m2 at indicated distance from release point Site: Duck Pond

0m 10 m 20 m 30 m 0m 10 m 20 m 30 m 0m 10 m 20 m 30 m Release Point 82 24 11 North 78 44 22 28 20 South 38 32 36 East 30 38 52 8 West 26 30 36 34 38 48 Avg. 43.00 37.00 29.00 33.33 45.00 48.00 20.00 36.00 Site: Outdoor Recreation

Release Point 36 38 34 North 44 40 South 8 14 East 28 26 32 West 22 26 6 Avg. 31.33 25.00 6.00 23.00

Knapweed plants at the Cantonment I and Turkey Creek sites were examined for L. minutus emergence holes. Emergence holes were found at the Cantonment I site inside the cage and within 10-m of the open release site.

Seedheads were collected from the Cantonment I and Turkey Creek sites to determine the number of U. quadrifasciata and U. affinis galls. At each site, both L. minutus and U. affinis had been released in June 1997. Approximately 100 seedheads were collected from each release location for a total of 400 seedheads at both sites. Fifty seedheads were dissected from both L. minutus and U. affinis release areas for a total of 200 seedheads at both sites (Table 6). No galls were determined to be caused by U. affinis. However, the Urophora larvae were retained in individual containers for species confirmation upon emergence. Larvae were found from the 1st and 2nd generations, but the 1st generation larvae were dead.

April, 1998 A collection of the spotted knapweed seed head moth, Metzneria paucipunctella (Zeller), was received at Amarillo. A portion of the collection was sent to Fred Stahl at the Colorado Department of Agriculture, and the remainder was stored under refrigeration at Bushland for later release.

On April 21st, 1998, Cassida rubiginosa adults were found in field cages in which they had been released on musk thistle, Carduus nutans L., at Bushland, Texas in the late summer of 1997, indicating the C. rubiginosa overwintered in Bushland during 1997-98.

Plans of 1998

Greenhouse research in 1998 will be conducted at Bushland, TX. The objectives of the first study are: 1. compare C. rubiginosa damage on musk and Canada thistle and 2. determine what impact the host plant has on C. rubiginosa’s life span and fecundity. This will begin as soon as sufficient C. rubiginosa can be field collected from Bushland or Colorado.

Field research in 1998 will continue at Fort Carson. Plant height and density data will be recorded at all sites established in 1997 as well as sites established in 1998. Additional releases of C. achaetes, L. minutus, and U. affinis on spotted knapweed, and C. rubiginosa, L. planus, and U. cardui on Canada thistle will be made in 1998. In addition to these additive releases, new insects scheduled to be released in 1998 include: the sulphur knapweed moth, Agapeta zoegana (L.), blunt knapweed flower weevil, L. obtusus Gyll., and spotted knapweed seed head moth, Metzneria paucipunctella (Zeller) on spotted knapweed; and Canada thistle stem weevil, Ceutorynchus litura (F.) will be released on Canada thistle. Releases of broad-nosed seed head weevil, Bangasternus fausti (Reitter), knapweed peacock fly, Chatorellia acrolophi White and Marquardt, brown-winged root moth, Pelochrista medullana Staudinger, grey-winged root moth, Pterolonche inspersa Staudinger, bronze knapweed root-borer, Sphenoptera jugoslavica Table 6. Summary of Urophora quadrifasciata Larvae Recovered from Spotted Knapweed Seedheads. Species release Status Larval density1 Emerging adults Larval frequency distribution2 area within total/50 average/ std. total percent std. indicated site seedheadsseedheaderror error 012345678910 Site: Cantonment I Larinus minutus Live 31 0.620.23 26 83.90.53 368400100001 Dead 10 0.200.10 452201000000 Total 41 0.410.13 8110601100001

Urophora affinis Live 41 0.820.17 28 68.30.28 298840100000 Dead 23 0.460.12 3510311000000 Total 64 0.640.10 64181151100000 Site: Turkey Creek Larinus minutus Live 76 1.52 0.19 57 75.0 0.20 15 10 15 6 2 2 0 0 0 0 0 Dead 14 0.280.08 3811010000000 Total 90 0.900.12 53211572200000

Urophora affinis Live 56 1.120.16 37 66.10.16 1817771000000 Dead 23 0.460.14 378220100000 Total 79 0.790.11 5525991100000 1 Fifty seedheads were dissected from each sample. Number of larvae in galls. 2 Seedheads containing the specified number of larvae in fifty seedhead sample.

(Obenb.), and green clearwingfly, Terellia virens (Loew) will be released on spotted knapweed depending on availability of insects. Indications of insect damage to Canada thistle and spotted knapweed will be recorded. Plants will be examined for determination of insect establishment and spread. GPS mapping will be conducted in the spring of 1998 to determine the extent of weed infestations at release sites and to determine possible spread of established or newly colonized biocontrol agents.