Fencelines and Roadsides As Invasion Sites for Problematic Weed Species

Fencelines and Roadsides as Invasion Sites for Problematic Weed Species

Pub. No. 11/053

www.rirdc.gov.au

Fence Lines and Roadsides as Invasion Sites for Problematic Weed Species

by the Birchip Cropping Group Inc.

October 2011

RIRDC Publication No 11/053 RIRDC Project No AWRC 08-37

ISBN 978-1-74254-237-9 ISSN 1440-6845

Fence lines and roadsides as invasion sites for problematic weed species: final report Publication No. 11/053 Project No. AWRC 08-37

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Researcher contact details

Birchip Cropping Group Inc. 73 Cumming Ave Birchip VIC 3483 Ph: 03 5492 2787

Web: http://www.bcg.org.au/

In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form.

RIRDC contact details

Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600

PO Box 4776 KINGSTON ACT 2604

Phone: 02 6271 4100 Fax: 02 6271 4199 Email: [email protected]. Web: http://www.rirdc.gov.au

Electronically published by RIRDC in October 2011 Print-on-demand by Union Offset Printing, Canberra, at www.rirdc.gov.au or phone 1300 634 313

Foreword

The aim of this project was to identify weed species and biotypes that pose the greatest threats to production agriculture if incursion and dispersal were allowed to occur from roadside and fence-line areas into farming zones.

A random survey was carried out in order to gain information on the occurrence and distribution of weed species and biotypes along roadsides and fence lines throughout the southern Mallee region of Victoria. Seed bank levels and herbicide resistance status were determined for the species and biotypes collected.

The survey results showed that the most dominant weed species found along fence lines were those that were commonly found in growers’ paddocks - annual ryegrass and barley grass were present at 45 per cent of surveyed sites.

The best strategies for controlling the dominant weed species found along fence lines will be the same as those used in paddocks—for example, timely control of weeds and rotational use of herbicides with different modes of action.

This project was funded in Phase 1 of the National Weeds and Productivity Research Program, which was managed by the Australian Government Department of Agriculture, Fisheries and Forestry (DAFF) from 2008 to 2010. The Rural Industries Research and Development Corporation (RIRDC) is now publishing the final reports of these projects.

Phase 2 of the Program, which is funded to 30 June 2012 by the Australian Government, is being managed by RIRDC with the goal of reducing the impact of invasive weeds on farm and forestry productivity as well as on biodiversity. RIRDC is commissioning some 50 projects that both extends on the research undertaken in Phase 1 and moves into new areas. These reports will be published in the second half of 2012.

This report is an addition to RIRDC’s diverse range of over 2000 research publications which can be viewed and freely downloaded from our website www.rirdc.gov.au. Information on the Weeds Program is available online at www.rirdc.gov.au/weeds

Most of RIRDC’s publications are available for viewing, free downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313.

Craig Burns Managing Director Rural Industries Research and Development Corporation

iii

Contents

Foreword ...... iii

Summary ...... vi

Introduction ...... 1

Method ...... 2

Site identification ...... 2 Weed identification and population ...... 2 Measuring the weed seed bank ...... 2 Screening for herbicide resistance ...... 2

Results ...... 3

Weed populations ...... 5 Seed banks of the dominant species ...... 6

Discussion ...... 8

Conclusion ...... 9

References ...... 10

Tables

Table 1 Location of the sites surveyed ...... 4

Table 2 Number of sites where the four dominant weed species occur in the southern Mallee: a summary ...... 6

Figures

Figure 1 How samples were collected from the fence lines ...... 2

Figure 2 Incidence of identified weed species in the southern Mallee ...... 5

Figure 2 Differences in the ryegrass seed bank on either side of the fence: all survey locations ...... 7

Executive Summary

What the report is about

Methods used

A random survey was carried out in order to gain information on the occurrence and distribution of weed species and biotypes along roadsides and fence lines throughout the southern Mallee region of Victoria. The region surveyed was a square area bounded by Sea Lake to the north, Birchip to the south, Hopetoun to the west and Lalbert to the east.

Dominant weed species present at the time of sampling were counted on either side of the fence (road side and paddock side). Seed bank levels and herbicide resistance status were determined for the species and biotypes collected.

Results/key findings

The inspection carried out during June to August led to the identification of more than 20 visible weed species. The most dominant were annual ryegrass and barley grass; they were present at 45 per cent of surveyed sites. The other two dominant weed species were hedge mustard and brome grass. There appeared to be little difference between the dominant species found on the road and paddock sides of the fence.

From seed bank surveys, barley grass was the most dominant species that germinated, indicating there was a significant seed bank in the soil samples collected. Ryegrass was found at a lower seed bank level in comparison with barley grass, despite being present in the same plant density, as measured during the season.

Of the samples collected from the roadside and paddock side of cropping paddock fence lines and tested for herbicide resistance, only one - an annual ryegrass population - was found to exhibit resistance to sulfometuron. No resistance to glyphosate or 2,4-D was found. These results suggest that the incidence of weed species with herbicide resistance along fence lines in Victoria’s southern Mallee is low.

Implications for relevant stakeholders for:

Fence-line weed control should be part of integrated weed management in order to avoid the onset of herbicide resistance, especially resistance to glyphosate.

Recommendations

Although the level of herbicide resistance was found to be low in this survey, repeated use of herbicides from the same group would probably lead to resistance to those herbicides. The potential risk of in-paddock weeds developing glyphosate resistance has significant implications for farmers in the short, medium and long term.

The results of this survey can be used to increase growers’ awareness and promote action to concentrate on controlling the dominant weed species (ryegrass and barley grass) found along fence lines. The best strategies will be the same as those used in paddocks—for example, timely control of weeds and rotational use of herbicides with different modes of action.

vii

Introduction

Roadsides and fence-line areas throughout Australian agricultural regions are typically poorly managed and provide sites for the incursion of weeds into adjoining agricultural land. The weed species present are observed to be the same as those that dominate the farming landscapes. Proliferation of these weed populations supported by large seed banks along roadside and fence-line areas creates a continual supply of weed seed and pollen to adjacent farming lands. There is potential for these weed populations to act as both a sink and a source for herbicide-resistant genes.

Resistance-prone species such as annual ryegrass can disperse genes for herbicide resistance over distances of up to 2 kilometres via wind-borne pollen dispersal. As a result, although initially originating from within crop areas exposed to herbicide selection, genes for resistance are likely to be dispersed and to accumulate in adjacent weed populations on roadsides and fence lines. From these areas pollen dispersal and gene movement can occur freely each growing season. It is well recognised that weed and volunteer crop species growing in these areas act as alternative hosts for many agricultural pests and diseases. The imposition of inadequate management systems has, however, ensured that numerous weed species in particular have been able to establish themselves and proliferate throughout Australian dryland cropping regions. Large weed populations will remain entrenched in roadside and fence-line areas for many years in the absence of strategic long-term management.

The aim of this project was to identify weed species and biotypes that pose the greatest threats to production agriculture if incursion and dispersal are allowed to occur from roadside and fence-line areas into farming zones.

Method

Site identification

The region surveyed was a square area bounded by Sea Lake to the north, Birchip to the south, Hopetoun to the west and Lalbert to the east. The region was divided into a grid, and three survey locations were randomly identified within each grid section. Fifty random sites were surveyed.

Weed identification and population

Dominant weed species present at the time of sampling were counted in 1 x 5–metre areas on either side of the fence (road side and paddock side) in 0.1–square metre quadrats (three counts per area). The counts were then averaged and converted to plants per square metre. Figure 1 shows the area where the samples were collected in relation to the fence line.

Roadside 5 metres 1 metre

Fence

1 metre 5 metres Paddock

Figure 1 How samples were collected from the fence lines

Measuring the weed seed bank

To determine the seed bank density of the weed species present, 10 soil cores (10 centimetres deep and 6 centimetres in diameter) were taken—five on the paddock side of the fence and five on the road side. The soil samples were then placed in paper bags, one for each area, and put in a greenhouse. After four weeks the soil was spread onto newspaper-lined potting trays (30 x 30 x 5 centimetres). The trays were stored in a cool environment (less than 20°C) with sunlight and watered twice daily for three months. Every three weeks emerged weeds were identified and counted. After counting, the weeds were removed from the trays. To stimulate further germination, a fork was used to ‘tickle’ the soil surface after each counting.

Screening for herbicide resistance

In order to determine the resistance status of the weed species that dominate the survey areas, mature seed heads of the dominant weed species were collected. (It was necessary to collect a large sample— more than 10 000 seeds—if the resistance test was to be thorough.) The collected seeds were placed in paper bags, one bag for each species. The paper bags were then stored in a greenhouse for drying and maturing. It was noted if the weed seeds were not fully mature at the time of survey: when this was the case a return visit to the site at a later date was made to collect mature seed.

The mature seed heads from the identified dominant weed species were screened for herbicide resistance at the Plant Science Consulting Laboratories at the University of Adelaide. The samples were then thrashed and cleaned before being grown in pots.

Seeds of each weed species were sown in 10 x 10–centimetre square pots and allowed to germinate. A single pot for each population was used for each herbicide applied. One pot per sample was left untreated, as an unsprayed control.

At the two-leaf stage (three weeks after sowing) all the species were sprayed with 20 grams per hectare of Oust® (active ingredient sulfometuron-methyl) and wetter. All the grass species were treated with 1 litre per hectare of Roundup® Powermax™ (active ingredient glyphosate) and wetter. At the three- leaf stage (four weeks after sowing) all the broadleaved weed species were treated with 600 millilitres per hectare of 2,4-D Amicide® 625 (active ingredient 2,4-D amine).

Three weeks after spraying weeds were scored as dead or alive. Results

Site selection took place in June and sites were visited twice during the growing season (June to August). Table 1 lists the coordinates and direction of the individual sites surveyed.

Table 1 Location of the sites surveyed

Fire Site map ref. no. no. Latitude Longitude Direction 1 185 A 35.672916 142.467613 Henty Highway east of Hiltons Road, heading towards Lascelles 2 185 B 35.630791 142.636013 Off Sunraysia and north along Pearce Road 3 185 C 35.766433 142.457314 Off Goyura east school bus road and north along Hatchers Road 4 185 D 35.73648 142.606316 Two Mile Road, east of Pohlners Road 5 185 E 35.820875 142.506409 Brains Road, north of Rosebery East Road 6 185 F 35.838551 142.621937 Rosebery East – Grogan Road west of Watchupga West Road 7 186 A 35.614186 142.706051 Duthies track, north of Hopetoun–Sealake Road 8 186 B 35.663154 142.812309 Steeles Road, west off Birchip–Sealake road 9 186 C 35.746094 142.744331 Adcock Road, south of Dennehys Road 10 186 D 35.693692 142.876682 Leuhmans Road, east off Birchip–Sealake road 11 186 E 35.813916 142.708454 Wilkur–Watchupga road, north of Acklands Road 12 186 F 35.835072 142.878399 Sealake–Birchip road, south of Whinmere Road 13 187 A 35.640976 142.961311 Bibbys Road, south of Berriwillock–Woomelang road 14 187 B 35.621163 143.083191 Berriwillock–Springfield road, east of Barnes Road 15 187 C 35.708329 142.907238 McNally Road, west of Drury Road 16 187 D 35.716552 143.05109 Watts Road, south of Walshand Arnolds Road 17 187 E 35.839664 142.941399 Rosetta Lane, north of Tank Road 18 187 F 35.803614 143.038559 Henessays Road, west of Poyners Road 19 188 A 35.63107 143.143272 Track east of Barry’s Road, south of Powers Road 20 188 B 35.630372 143.239231 Powers Road, west of Murnungin Road 21 188 C 35.731464 143.169537 Hayes Road, east of Rohans Road 22 188 D 35.758214 143.27528 Dog netting fence road, West of Nullawl–Lalbert road 23 188 E 35.839664 143.153057 Loways Road, west of Calder Highway at Nullawil 24 188 F 35.799994 143.255882 Nullawil–Lalbert road, north of Smiths Road 25 189 A 35.637627 143.394585 Bennett Road, east of Donald – Swan Hill road 26 189 B 35.593111 143.520584 Thompson Road, east of Swan Hill – Quambatook road 27 189 C 35.739128 143.39922 Ingram Road, east of Donald – Swan Hill road 28 189 D 35.714601 143.506336 Mitchell Road, west of Swan Hill – Quanbatook road 29 189 E 35.7727 143.389263 Meehans Road, east of Donald – Swan Hill road 30 189 F 35.799855 143.528137 Adamthwaite Road, east of Quambatook – Swan Hill road 31 209 A 35.892527 142.486153 McQueens Road, north of Macphersons Road 32 209 B 35.926313 142.632923 Rupanyup Road, north of Beulah East Road 33 209 C 36.014394 142.458687 Constable Road, south of Galaquil East Road 34 209 D 36.009117 142.635841 Rupanyup Road, south of Galquil Road 35 210 A 35.885851 142.729225 Crosbie Road, north of Kinnabulla West Road 36 210 B 35.919501 142.825871 Gould Road, west of Sunraysia Highway, past S bend 37 210 C 35.977451 142.666225 Hunt Road, south of Birchip–Rainbow road 38 210 D 35.985785 142.83308 Cooper Road, south of Sunraysia Highway

Fire Site map ref. no. no. Latitude Longitude Direction 39 211 A 35.878758 142.94466 Marbed–Curyo road, off old Berriwillock road 40 211 B 35.919779 143.075981 McColl Bridge North Road, south of Hunts Road 41 211 C 35.963836 142.941227 McCleans Road, north of Birchip–Berriwillock road 42 211 D 35.988702 143.098469 Dunns Road, south of Dumosa–Birchip road 43 212 A 35.875281 143.144817 Nullawil South West Road, south of Nullawil–Birchip road 44 212 B 35.895586 143.298798 Morrisons Road, east of Donald – Swan Hill road 45 212 C 35.965781 143.155632 McNaughtons Road, west of Nullawil South Road 46 212 D 35.955499 143.318195 Chinamans Road, south of Turnbulls Road intersection 47 213 A 35.87069 143.380508 Gardner Road, north of Nullawil–Quambatook road 48 213 B 35.899063 143.480759 McAuley Road, east of Good Road 49 213 C 35.934305 143.36566 Arnels Road, east of Charlton – Swan Hill road 50 213 D 36.009256 143.525047 Hills Road, west of Barraport West and Mackwood roads

Weed populations

The inspection carried out during the growing season led to more than 20 weed species being identified. The most dominant weed species in the region were Lolium rigidum (annual ryegrass) and Hordeum leporinum (barley grass); they were present at 45 per cent of surveyed sites. The other two dominant weed species were Sisymbrium orientale (hedge mustard) and Bromus diandrus (brome grass)—see Figure 2. All four of these weed species are commonly found in paddocks throughout the region, so the threat that exists in paddocks also applies to fence lines.

42 Ryegrass 56 40 Barley Grass 50 18 Hedge Mustard 26 24 Spear Grass 18 10 Brome grass 20 10 Wild Oats 14 4 Silver Grass 8 10 Wild Turnip 8 0 Tumble Weed 4 0 Perennial Barley 4 2 Veldt grass 2 Roadside Paddock 4 Yellow burrweed 2 2 Pink Weed 2 2 Windmill Grass 0 2 Wallaby Grass 0 2 Sowthistle 0

0 10 20 30 40 50 60 % incidences

Figure 2 Incidence of identified weed species in the southern Mallee

There appeared to be little difference between the dominant species found on the road and paddock sides of the fence. The incidence of both barley grass and ryegrass was noticeably reduced on the

paddock side of the fence, possibly as a result of better management of weeds on that side. Table 2 summarises the incidence of specific weeds, as determined by the weed counts during the season. A threshold of 50 plants per square metre is commonly used to identify major weed burdens, and it is used here to separate the ranges from the results.

Table 2 Number of sites where the four dominant weed species occur in the southern Mallee: a summary

Incidence Roadside Paddock Weed populations Weed species (plants/m2) No. % of sites No. % of sites Annual ryegrass 0 22 44 29 58 <50 11 22 7 14 >50 17 34 14 28 Barley grass 0 25 50 30 60 <50 8 16 3 6 >50 17 34 17 34 Hedge mustard 0 37 74 41 82 <50 9 18 8 16 >50 4 8 1 2 Brome grass 0 40 80 45 90 <50 7 14 2 4 >50 3 6 3 6

Seed banks of the dominant species

Seed bank levels for each survey site were determined in autumn 2010. Barley grass was the most dominant species that germinated, indicating there was a significant seed bank in the soil samples collected. Ryegrass was found at a lower seed bank level in comparison with barley grass, despite being present in the same plant density, as measured during the season.

There were differences in the number of seeds found on either side of the fence. Where ryegrass was present there was a reduction in the number of seeds that germinated at 62 per cent of the paddock sites (17 out of 27 sites) compared with the roadside. Figure 2 shows the differing levels of the ryegrass seed bank on either side of the fence. In the remaining 10 sites, where ryegrass levels were greater on the paddock side, that circumstance might be attributable to errors associated with random sampling or it could be an indicator of resistance or where there was no attempt to control ryegrass on the paddock side.

30,000

25,000 Roadside Paddock

20,000

15,000 Seeds/m2

10,000

5,000

0 Site no

Figure 2 Differences in the ryegrass seed bank on either side of the fence: all survey locations

Discussion

The survey allowed assessment of the level of resistance in the paddocks, which provides valuable information for determining the best management practices for fence-line weed control. By demonstrating that fence-line weeds can pose the same threat as those found in a paddock, the results show that controlling these weeds is important. The survey cannot account for weed species that require differing temperatures and light or dark periods to stimulate germination. It is obviously difficult to replicate such environmental influences, although the survey did allow for evaluation of the dominant weed species present.

The weed counts taken showed that barley grass and ryegrass were the most dominant species, followed by hedge mustard and brome grass. On separating the densities according to populations greater or less than 50 plants per square metre, it became evident that when barley grass and ryegrass are present they are more likely to be present in larger numbers (more than 50 plants per square metre) than lower (fewer than 50 plants per square metre). This was certainly more obvious on the paddock side of the fence, where twice as many sites had more than 50 plants per square metre. This could be a result of those sites not having previously been managed by spraying or cultivation.

Of the weed seeds found in the soil, barley grass was the dominant species. Barley grass is early maturing compared with ryegrass and is not hard-seeded, which means that 99 per cent of seeds will germinate or decay in the ensuing year. Ryegrass has a much longer seed survival time: viable seeds can persist after four years in undisturbed soil; burial of the seeds can further increase dormancy. It is possible that a certain amount of ryegrass seed remained dormant during the sampling period (Peltzer & Matson 2002).

Seed production of barley grass is relatively less prolific than that of ryegrass. In the absence of competition, a barley grass plant can produce up to 2000 seeds compared with a ryegrass plant producing 3000 (Purba et al. 1996; Pedersen et al. 2006).

A survey of weeds collected from the roadside and paddock side of cropping paddock fence lines tested for herbicide resistance to glyphosate, 2,4-D or sulfometuron (a non-selective sulfonylurea herbicide). Only one sample—an annual ryegrass population—was found to exhibit resistance to sulfometuron. No resistance to glyphosate or 2,4-D was found. These results suggest that the incidence of weed species with herbicide resistance to glyphosate, 2,4-D or sulfometuron along fence lines in Victoria’s southern Mallee is low.

Conclusion

The survey results showed that the most dominant weed species found along fence lines are those that are commonly found in growers’ paddocks. Degrees of herbicide resistance have been widely reported in annual ryegrass, barley grass and brome grass populations in the Wimmera–Mallee. Management of these populations has typically begun in problem paddocks; little attention is paid to fence lines.

Glyphosate is the most relied on herbicide for controlling in-paddock and fence-line weeds. Although the level of herbicide resistance was found to be low in this survey, repeated use of herbicides from the same group will probably lead to resistance to those herbicides. The potential risk of in-paddock weeds developing glyphosate resistance has significant implications for farmers in the short, medium and long term.

References

Pedersen, BP, Neve, P, Andreasen, C & Powles, SB 2006, ‘Ecological fitness of a glyphosate-resistant Lolium rigidum population: growth and seed production along a competition gradient’, Basic and Applied Ecology, vol. 8, pp. 258–68.

Peltzer, SC & Matson PT 2002, ‘How fast do the seedbanks of five annual cropping weeds deplete in the absence of weed seed input?’ Proceedings of the 13th Australian Weeds Conference, Perth 8–13 September 2002, pp. 553–5.

Purba, E, Preston, C & Powles, SB 1996, ‘Growth and competitiveness of paraquat-resistant and - susceptible biotypes of Hordeum leporinum’, Weed Research, vol. 36, pp. 311–17.

Fence Lines and Roadsides as Invasion Sites for Problematic Weed Species Pub. No. 11/053 by the Birchip Cropping Group Inc. Roadsides and fence-line areas throughout Australian agricultural regions This project was funded in Phase 1 of the National Weeds and are typically poorly managed and provide sites for the incursion of weeds Productivity Research Program, which was managed by the Australian into adjoining agricultural land. The weed species present are observed Government Department of Agriculture, Fisheries and Forestry (DAFF) to be the same as those that dominate the farming landscapes and from 2008 to 2010. The Rural Industries Research and Development potentially act as both a sink and a source for herbicide-resistant genes. Corporation (RIRDC) is now publishing the final reports of these projects. The aim of this project was to identify weed species and biotypes that pose the greatest threats to production agriculture if incursion and Phase 2 of the Program, which is funded to 30 June 2012 by the dispersal were allowed to occur from roadside and fence-line areas into Australian Government, is being managed by RIRDC with the goal of farming zones. reducing the impact of invasive weeds on farm and forestry productivity as well as on biodiversity. RIRDC is commissioning some 50 projects A random survey was carried out in order to gain information on the that both extends on the research undertaken in Phase 1 and moves into occurrence and distribution of weed species and biotypes along roadsides new areas. These reports will be published in the second half of 2012. and fence lines throughout the southern Mallee region of Victoria. Seed bank levels and herbicide resistance status were determined for the species This report is an addition to RIRDC’s diverse range of over 2000 research and biotypes collected. publications which can be viewed and freely downloaded from our website www.rirdc.gov.au. Information on the Weeds Program is available The survey results showed that the most dominant weed species found online at www.rirdc.gov.au/weeds along fence lines were those that were commonly found in growers’ paddocks - annual ryegrass and barley grass were present at 45 per cent of Most of RIRDC’s publications are available for viewing, free surveyed sites. downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313. The best strategies for controlling the dominant weed species found along fence lines will be the same as those used in paddocks—for example, timely control of weeds and rotational use of herbicides with different modes of action.

This publication can be viewed at our website—www.rirdc.gov.au. Contact RIRDC: Ph: 02 6271 4100 All RIRDC books can be purchased from: Level 2, 15 National Circuit Fax: 02 6271 4199 Barton ACT 2600 Email: [email protected] web: www.rirdc.gov.au www.rirdc.gov.au PO Box 4776 Kingston ACT 2604