Rangelands 9(6), December1987 249 andprobiemsassociated with this plantare increasing. Research Dollahlts, J.W., and T.J. Allen. 1959. Feedingperennial broomweed and educational programs are neededto help ranchers man- to cattle, swine, sheep,goats, rabbits, guinea pigs and chickens. Tex. Sta. 2105. age perennial broomweed infestations more effectively. Agr. Exp. Prog. Rep. Matthews, Frank P. 1936. The toxicityof broomweed( microcephala) for sheep, cattle and goats. J. Amer. Vet. Med. Literature Cited Assoc.88:56-61. Corrll, D.S., andM.C. Johnston.1970. Manualof the vascularplants McDanIel, KIrk C., RD. Pleper, and GB. Donart. 1982. Grass of . Tex. Res. Foundation. Renner, Tex. 1,881. p. responsefollowing thinningof broom snakeweed. J. Range Man- Dollahite, J.W.,and W.V. Anthony. 1956. Experimentalproduction of age. 35:219-222. abortion, premature calves, and retained placentas by feeding a Ragsdale,B.J. 1969. Ecologicaland phenological characteristics of species of perennial broomweed. Tex. Agr. Exp. Sta. Prog. Rep. perennial broomweed. Ph.D. Diss., Tex. A&M Univ., College 1884. Station. Dollahlts, J.W., and W.V. Anthony. 1957. Poisoning of cattle with Texas County StatIstics.1994. USDA Bulletin 223, AustIn, Tex. Gutierreziamicrocephala, a perennial broomweed.J. Amer. Vet. Ueckert, D.N. 1979. Broom snakeweed:Effect on shortgrassforage Med. Assoc. 130:525-530. productionand soil waterdepletion. J. RangeManage. 32:216-220.

Knapweed Infestation Darcy A. Yule

Spotted knapweedis arangeland pest ofsouth and central British Columbia and of the northwest United States. The planthas invadedrangelands in an overgrazed condition and MAP of BRITISH COLUMBIA areas of soil disturbance. Fortunately, knapweed has never gained afoothold on theforested rangelandsof west central B.C. (Prince George to Prince Rupert). Periodically, how- ever, small infestations have been observed along the main highway (#16)and railwaycorridors. These infestationshave been identified anderadicated, using picloram, asquickly as possible by the Provincial Ministries of Highwaysor Agricul- ture, RegionalDistricts (counties), or theCanadian National Railway (C.N.R.). Mrs. E.R. Jaarsma,an adjacent ranch owner,first reported an infestation of spotted knapweed at the Barrett Station C.N.R.siding in thefail of 1983. Thissiding is located 5 miles west of Houston,B.C., on DistrictLot 712, CR5. At the time of discovery,all stages of knapweed development—dead mature, SHOWING THE rosette with stems, and rosette—werepresent. BARRETT STATION STUDY SITE Knapweedcan over-winter as a rosette or as seed. In the followingyear, the may produce one or two flowering stems. However, in future years as the plant matures, a Site multi-stemmed Description bushy, plant develops. TheBarrett Station siding is about 5 hectaresin size. There Based on habits and the initial knapweed's development are three sets of railway tracks: the main line, the primary discovery year (1983), the time of initial seed introduction and the The three tracks are had to have occurred siding, secondary siding. prior to or during the 1981 growing roughly 2 meters apart and cover a strip of land, 12 meters season.Thus, at the time of thisstudy (July 1984), the infes- wide, centered in the middle of the of the tation had its fourth There was an right way. Along begun growing season. secondary siding therewas a small portable sawmill which interest inassessing the rate of spreadof knapweedin terms milled ties for the C.N.R. of the area covered since initial infestation. railway The plant cover of the area varies,with native plantssuch The author at the time of this study was the Regional Range Officer, B.C. aswillow, fireweed, cow parsnip, wildrye, and fringedbrome ForestService, Smithers,B.C. He Is now the B.C.F.S. District Managerat Box the undisturbed area and 40. McBride, B.C., Canada V0,J2E0. dominating tame grasses and legumes(Kentucky bluegrass,creeping redfescue, Timothy, 250 9(6), December1987 smooth brome and clover) on disturbed areas. Although not rosettes. The number and growth stage of all knapweed recorded as part of this project, the ground cover is esti- found were recorded at the distance noted on the hip mated to be 80%to 90%on mostof the area. Hayfieldsabut chain. both sides of the railway right of way. The presenceor absence of knapweed is complicated by Results the fact thatthe area was treated with picloram (Tordon 10k) The number of knapweed plants observed and their loca- afterdiscovery in 1983. Therefore,to estimatethe knapweed tions were plotted on a 1 mm:1 m scale map of the siding. spread, the 1984 survey of this site had to rely on both new This map gave an overall layoutof the site. The infestation couldthen be shown in relation tothe existing ground cover. Thedistribution and densityof the plants were determined by each transect (lengthwise) and by 10-meter intervals across all 12 transects. For example, on transect #6 there were 27 dead mature plants, 84 rosettes with flowering stems, and 25 rosettes;on the strip of ground at 280 to 289 meters from the baselinethere were 58 dead mature plants, 14 rosetteswith flowering stems, and 15 rosettes. Discussion Ninety-five percent of the plants found were located on areasthat had some soil surface disturbance. The otherfive percent of the knapweed plants were on small bared areas within the larger heavy ground cover areas. Myers and Berube (1983) found that diffuse knapweed followed a sim- ilar pattern of establishment. Off loading equipment or railway car clean-up was attrib- uted to be the initial seed source for the infestation. This theoryis supported bythe evidence that thehighest number ofdead mature plants were found along the south side ofthe secondary siding. Dead mature plant frequency decreased and young plant frequency increasedas one wentnorthward fromthe initial infestation site. Thus,the infestation appeared to be moving across the tracks. The infestation's lack of movementsouth from the initial site wasattributed to the picloram application andthe heavy equipment movementassociated with the mill site. The her- bicide applicators must havemissed most of thenorth site of the iniestaton. Dead mature spottedknapweed plants between f/iaprimary and The initialinfestation was on a .016-hectare area at the 280 secondary sidings. to 299-meterinterval along thesecondary siding. This infes- tation began duringor before the 1981 growing season.By plants and previous year's dead mature plants. thetime of the study (fourth growing season,1984) theinfes- tation had to an area of 0.75 hectares to 429 Methods expanded (220 meters across all threerail lines). The knapweed site was sampled on July 6, 1984. A simple In atotal context, this representsa spread rateover thetwo method of locating and plotting all knapweed plants was intervening growing seasons (1982, 1983) of 0.367hectares developed. An ocular reconnaissanceof the infestation was per year. If left unchecked,the spread ratemay well increase done usingtransects asa baseto record plant sightings. This above 0.367 hectares per year as more and more plants ocular/transect method allowed for total coverage of the would produce seed. infestation area. Twelve transects were laid out paralleling Since the 1984 study, the Barrett Station site has been the railway tracks. These transects were spaced across the treated againwith picloram andall the knapweedplants were siding area from the north side (transect #1) to the south pulled up and burned. (transect #12). To prevent similar infestations, care should be taken to Distancesalong the transects were measuredby the use of prevent the possibletransport of knapweedplants or seed in "Topfil Hip Chain". The transects' baseline was the road hayor onvehicles or other equipment.Proper reclamationof crossing atthe east end of the siding. Transects were mea- disturbed areasis necessarywhen site activityis completed. sured by walking up and down the track right of way until vegetation did not permit passage or the baseline was Literature Cited reached. Myers, J.H., andD.E. Berub..1983. Diffuse knapweedinvasion into Knapweed plants present were noted b their growth in thedry interior of British Columbia. Can..l. Plant Sci. stage: dead mature, rosettes with flowering stems, and 63:981-987 (Oct. 1983).