Bushland Weeds Manual - Environmental Weeds Action Network

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50 Chapter 4 Corms, Bulbs and Tubers Case Studies An integrated approach Initially it was thought the population could be managed with an intensive hand-weeding program. The first year this was tested it became evident it was going to be extremely labour intensive and expensive. Effective, affordable and appropriate control in the wetlands required a combination of carefully targeted hand-weeding and herbicide application. From 1999-2002 bush regenerators were employed in the wetlands through September/October to manually remove small isolated populations in undisturbed areas and populations growing around the edges of claypans where herbicide use is inappropriate. At this time of the year the wetland soils are still soft and entire plants including corms come out quickly and easily with minimal soil disturbance. Workers hand-removing Harlequin Flower in the wetlands Herbicide trials have indicated that Harlequin Flower can be controlled effectively with metsulfuron methyl (Brush-off ® ) at 2.5 g/ha (0.1 g/15 L) with limited impact on co-occurring native species in the Brixton Street Wetlands (Brown and Brooks in press c, Table 1). The Harlequin Flower populations are generally fairly discrete and are only ever spot sprayed. A spray contractor with a knowledge of the flora and a background in bushland work has been employed to carry out chemical control on heavier infestations in more disturbed areas and on the drier sites. To be effective over the three years the project has relied on workers having an understanding of the distribution of Harlequin Flower across the Brixton Street Wetlands. The populations were mapped at the start of the project in 1998. These maps helped set priorities and allowed for a carefully targeted works program revisiting small isolated populations over a number of years. The maps also enabled us to accurately record works carried out over time and will provide some information on the effectiveness of the management strategy. Figure 1. Distribution of Harlequin Flower • across the Brixton Street Wetlands, September 1998. Deep claypan (clay) - Melaleuca lateritia shrubland, Amphibromus grassland Wet flats - Viminaria juncea tall shrubland/dry flats - mixed low shrublands Shallow claypans (wet) - Pericalymma open heath Melaleuca shrubland Uplands - Marri Woodlands Disturbed areas Table 1. Native flora co-occurring with Harlequin Flower in the trial plots. Annual Herbs Perennial Herbs-Geophytes Aphelia cyperoides Burchardia congesta Centrolepis aristata Burchardia multiflora Drosera glanduligera Drosera menziesii ssp. menziesii Goodenia micrantha Philydrella drummondii Hydrocotyle alata Sowerbaea laxiflora Isolepis cernua Tribonanthes longipetala Schoenus odontocarpus Utricularia violacea Siloxerus humifusus Shrubs Perennial Herbs Acacia lasiocarpa var. bracteolata Borya scirpoidea Kunzea micrantha ssp. micrantha Chorizandra enodis Pimelea imbricata var. major Chorizandra multiarticulata Verticordia densiflora Cyathochaeta avenacea Juncus capitatus Lomandra spp Meeboldina canus Mesomelaena tetragona Viminaria juncea
Chapter 4 Corms, Bulbs and Tubers Case Studies Table 2. Management actions across Harlequin Flower populations in 1998 to 2001. YEAR ACTION/TREATMENT 1998 Transects put in place over population. Numbers of Harlequin Flower in each 1 m x 1 m plot counted. No treatment. 1999 Numbers of Harlequin Flower in plots counted again. Population appears to be expanding rapidly. Hand-weeding program attempted across wetlands and all plots hand-weeded. 2000 Plots rescored. Also this year recorded cover estimates (Braun-Blanquet 1965) for all other species, weeds and natives, in plots. Hand-weeding program this year restricted to isolated populations and those in wetter areas. This population (being monitored) sprayed 2.5 g/ha Brush-off ® + Pulse ® 2 mL/L. 2001 Plots rescored and control program continued as for 2000. More detailed monitoring over time In September 1998 three 30 metre long transects were run from the disturbed edge of the bushland, through the Harlequin Flower population. Along each transect quadrats (1 m x 1m) were placed at five metre intervals. The aim was to monitor changes in the density of the Harlequin Flower population Average number of plants 10 5 0 1998 1999 2000 2001 Year over time and to gain an understanding of the effectiveness of the management actions. The populations of mature (Figure 2a) and juvenile Harlequin Flower (Figure 2b) increased from 1998 to 1999 before a management program was in place. Hand-weeding was very effective (1999-2000) and so was the herbicide treatment (2000- 2001). The increase in Harlequin a Average number of Sparaxis by year and distance from edge b Average number of juvenile Sparaxis by year and distance from edge 25 1-2 m 500 1-2 m 6-7 m 6-7 m 20 12-13 m 18-19 m 400 12-13 m 18-19 m 24-25 m 24-25 m 15 29-30 m 300 29-30 m Average number of plants 200 100 0 1998 1999 2000 2001 Year Figure 2. a) Average number of mature (flowering) Harlequin Flower plants and b) juvenile Harlequin Flower plants in plots (1 m x 1 m) along three 30 metre transects over four years (ie three replicates used). Flower one to two metres from the edge over 2000-2001 may indicate that the area missed herbicide treatment. If so it illustrates that there will be reinvasion of populations if follow-up is not consistent in the early years of the control program. Funding Funds have to be sought by the Friends of Brixton Street Wetlands each year to continue the work. It is anticipated that the cost will drop after the first three years. Unless the control program is consistently applied each year in the early stages, reinvasion will probably eventuate. The work at Brixton Street illustrates that with some resources and a carefully targeted and consistent effort over time, effective control of seriously invasive geophytes like Harlequin Flower moving into undisturbed bushland is possible with minimum off-target damage to cooccurring native species. Source: Brown and Brooks (in press c) Table 3. Cost of works, including funding sources, over three years. * A number of volunteers assisted the bush regenerators with their work in the wetlands TREATMENT RATE 2000 2001 2002 Physical removal ( 2 x bush regenerators) * 48 hrs @ $17.50 x 2 $1,680.00 $1,680.00 $1,680.00 Spot spray dense infestations (contractor) $60.00 per hour $600.00 $600.00 $300.00 Total $2,280.00 $2,280.00 $1,980.00 Funding source Wildflower Society W.A Dept. of Conservation Dept. of Conservation (Inc.) Perth branch & Land Management & Land Management 51
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Bushland Weeds A practical guide to
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Acknowledgments This manual is the
Page 6 and 7: iv Introduction The Banksia, Tuart
Page 8 and 9: 2 Chapter 1 The Project Blue Gum La
Page 10 and 11: 4 Chapter 1 The Project Both Arum L
Page 12 and 13: 6 Chapter 2 Managing Weeds in Bushl
Page 14 and 15: 8 Chapter 2 Managing Weeds in Bushl
Page 16 and 17: 10 Chapter 3 Grass Weeds Many grass
Page 18 and 19: 12 Chapter 3 Grass Weeds Box 3.3 Gr
Page 20 and 21: 14 Chapter 3 Grass Weeds • Transi
Page 22 and 23: 16 Chapter 3 Grass Weeds Control te
Page 24 and 25: 18 Chapter 3 Grass Weeds Rhizomatou
Page 26 and 27: 20 Chapter 3 Grass Weeds Case Studi
Page 34 and 35: Chapter 3 Grass Weeds Management Ta
Page 36 and 37: Chapter 3 Grass Weeds Management Ta
Page 38 and 39: 32 Chapter 4 Corms, Bulbs and Tuber
Page 58 and 59: Chapter 4 Corms, Bulbs and Tubers W
Page 60 and 61: Iridaceae Moraea miniata Two Leaf C
Page 62 and 63: Chapter 5 Broadleaf Herbs, Sedges a
Page 64 and 65: 58 Chapter 5 Broadleaf Herbs, Sedge
Page 72 and 73: Chapter 5 Annual Broadleaf Herbs, S
Page 74 and 75: Chapter 5 Annual Broadleaf Herbs, S
Page 76 and 77: Chapter 5 Perennial Broadleaf Herbs
Page 78 and 79: Chapter 5 Perennial Broadleaf Herbs
Page 80 and 81: 74 Chapter 6 Trees, Shrubs and Clim
Page 92 and 93: Chapter 6 Trees, Shrubs and Climber
Page 94 and 95: Chapter 6 Trees, Shrubs and Climber
Page 96 and 97: 90 Chapter 7 Weed Mapping in Remnan
Page 98 and 99: 92 Chapter 7 Weed Mapping in Remnan
Page 100 and 101: 94 Chapter 8 Herbicide Use in Bushl
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100 Final Note In the end, environm
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102 References 1 Aarssen, L.W., Hal
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104 References 101 Dixon, B. (2002)
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106 References 204 Mann, R. (1998)
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108 307 The Nature Conservancy (200
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