Florestina Tripteris DC. Prod.) HERBICIDE SCREENING for a RECENT INVASIVE SPECIES in CENTRAL WESTERN QUEENSLAND

Proceedings of the 21st Asian Pacific Weed Science Society Conference (Editors: B. Marambe, U.R. Sangakkara, W.A.J.M. De Costa, and A.S.K. Abeysekara), 2-6 October 2007, Colombo, Sri Lanka. STICKY FLORESTINA (Florestina tripteris DC. Prod.) HERBICIDE SCREENING FOR A RECENT INVASIVE SPECIES IN CENTRAL WESTERN QUEENSLAND

E. Sparkes and M. Rogers Biosecurity Queensland, Department of Primary Industries and Fisheries, Brisbane, Queensland, Australia. [email protected]

Abstract: Florestina tripteris DC. Prod. (Sticky Florestina) is an annual weed that is established in the Tambo and Barcaldine Shires of Central Western Queensland, Australia. It was accidentally introduced from Southern Texas, U.S.A in a consignment of Buffel grass seed in 1964. It is a member of the Asteraceae family and grows up to 1 m in height. Florestina tripteris has grey-green leaves and small white flowers. The pecies produces hundreds of seeds that are sticky and are spread easily by stock and machinery, including vehicular traffic. Florestina tripteris has the ability to survive dry conditions, germinating only after rain and often completing its life cycle within a month. A herbicide screening trial commenced in April 2002. The mortality of overall foliar sprayed plants was high but could have been improved by targeting plants following germination in early spring. The best three foliar overall treatments were bromoxynil 200 g l-1 at 4 g a.i. l-1 (controlling 85% of weeds sprayed), 2,4-D acid 300 g l-1 at 17 g a.i. l-1 (controlling 75% of weeds sprayed) and 2,4-D dimethylamine salt 500 g l-1 at 16 g a.i. l-1 (controlling 70% of weeds sprayed). The best three treatments from a residual seedling control trial at Barcaldine site were clopyralid 300 g l-1 at 6 g a.i. l-1 (providing 0.6% of seedling recruitment of untreated areas), and metsulfuron methyl 600 g kg-1 at 0.24 g a.i. l-1 (giving recruitment counts that were 30% of the untreated areas) and triclopyr ester 300 g l-1 at 4.2 g a.i. l-1 + picloram 100 g l-1 at 1.4 g a.i. l-1 (giving 80% of seedling recruitment of the untreated areas). An Australian permitted registration allows for the use of 200 g 2,4-D amine + 200 g alcohol alkoxylate non-ionic surfactant 100 l-1 water to be sprayed alone, 2-3 weeks after germinating rains, but before bud and flower stage. Once budding and flowering have begun, a tank mix of 100 g 2, 4-D amine + 20 g metsulfuron methyl + 200 g alcohol alkoxylate non-ionic surfactant 100 l-1 in water will kill treated plants and reduce the number of germinants emerging following the next rain.

Key words: Control, herbicide, pasture, soil-moisture, toxic, weed.

Introduction

Florestina tripteris DC. Prod. (Sticky Florestina) was first investigated as a weed threat in the Tambo and Barcaldine Shires of Central Western Queensland in 2000. It was accidentally introduced from Southern Texas, U.S.A in a consignment of Buffel grass (Cenchrus ciliaris L.) seed in 1964 (Bucknell per. comm., 2000). Florestina tripteris is a member of the Asteraceae family, with lower leaves that are grey-green, simple and opposite and upper leaves trifoliate and alternate. The entire plant is covered in very short sticky white hairs. Plants attain 10 cm to 1 m in height at maturity and bear numerous flower heads with small white flowers (Turner, 1963). Florestina ripteris produces hundreds of seeds that are sticky and are spread easily by stock, machinery and people, particularly on areas where heavy traffic is common. It is an annual plant that has the ability to survive dry conditions and drought, germinating only after rain and sometimes completing its life cycle within a month while soil moisture is available. F. tripteris is a highly invasive weed that will prove hard to control because of its growth habit when invading pastures. It will grow as a monoculture along road verges and on bare disturbed areas, but tends to occur as isolated plants in amongst pasture species such as Buffel or Mitchell grass (Astrebla pectinata (Lindl.) F. Muell. and A. elymoides F. Muell. ex F.M. Bailey). Scattered plants with counts up to 5000 ha-1 have been recorded in pasture. The preferred areas of F. tripteris include roadsides, stock routes and disturbed or overgrazed pastures (Turner 1963). Newly graded roads and fence lines have been the sites of the densest infestations. The first Queensland Herbarium record for this species from the

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Materials and Methods

Herbicide screening trials were conducted in Queensland, 25 km south of Barcaldine (145°19”06’E, 23°47”40’S) and 50 km south-west of Tambo (145°56”12’E, 250°12”58’S) in March 2002. Both sites were treated with the same herbicides (Table 1).

Table 1. Herbicides trialled on F. tripteris , listed in order of effectiveness

Dilution Treatment Active constituent g a.i per 10 litres 1 200 g l-1 bromoxynil as noe 40 -1 2 300 g l 2,4-D acid 168 3 500 g l-1 2,4-D dimthylamine salt 160 -1 4 300 g l triclopyr ester 42 +100 g l-1 picloram 14

5 200 g l-1 bromoxynil as noe 80 6 300 g l-1 triclopyr ester 60 + 100 g l-1 picloram 20 7 300 g l-1 clopyralid as tipa 30 8 360 g l-1 glyphosate isopropyl ammine salt 144 9 300 g l-1 clopyralid as tipa 60 10 600 g kg-1 metsulfuron-methyl 2.4 11 200 g l-1 fluroxypyr ester 20 -1 12 360 g l glyphosate isopropyl ammine salt 72 13 200 g l-1 fluroxypyr ester 40 -1 14 500 g l 2,4-D dimthylamine salt 80 15 300 g l-1 2,4-D acid 84

16 200g l-1 fluroxypyr ester 80 17 600 g kg-1 metsulfuron-methyl 4 18 500 g l-1 dicamba as dma 80 19 360 g l-1 glyphosate isopropyl ammine salt 36 20 500 g l-1 dicamba as dma 40 600 g kg-1 metsulfuron-methyl 2.4 21 500 g l-1 dicamba as dma 40 22 500 g l -1 atrazine 80 23 600 g kg-1 metsulfuron-methyl 1.2 -1 24 500 g l atrazine 160 25 control noe = n-octanoyl ester, tipa = triisopropanolamine salt dma = dimethylamine salt

Twenty-four treatments involving 12 products were sprayed on F. tripteris by the spot foliar overall spray methodology or 1 m hand-held boom application technique. Plant condition was reflected as a visual rating index (Australian Weeds Committee, 1979). Ratings ranged from 1 indicating plant death to 6 indicating normal growth (Figure 1). The Barcaldine experiment was set out in randomly selected plots (size 10 m2) along Queensland stock route M217. Dominant plant species within this trial site were Acacia cambagei R.T.Baker and Ptilotus exaltatus Nees var. exaltatus. Scattered throughout the site were Acacia farnesiana (L.) Willd., Boerhavia schomburgkiana Oliv., Ocimum

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Proceedings of the 21st Asian Pacific Weed Science Society Conference (Editors: B. Marambe, U.R. Sangakkara, W.A.J.M. De Costa, and A.S.K. Abeysekara), 2-6 October 2007, Colombo, Sri Lanka. tenuiflorum.L. and C. ciliaris, in conjunction with native grasses A. elymoides and Astrebla squarrosa C.E. Hubb (Milson, 1995).

The days were fine with light breezes up to 2 m per second, having no effect on herbicide application. The temperature ranged between 32°and 39°C. A model 320 hand-pump Swiss-mex® compression sprayer with 9 litre capacity with Rega® 1 mm adjustable nozzles was used. The boom hand pump sprayer was a Swiss-mex® compression sprayer with 15 litre capacity fitted with four Hardi 41212 fan nozzles spaced 34 cm apart. Twenty-three plots were subjected to a 1 m boom foliar spray at 525 l ha-1. The spot spray technique used ~ 200 L ha-1 depending on F. tripteris density. Data were collected on 22nd and 23rd March 2002 (initial application), with the first herbicide effect assessment on 24th March 2002, and the second assessment made on 27th April 2002. Further assessments were made the following year (Figure 2) to determine the residual effects of herbicides upon seedling emergence. Treatment plots were replicated three times. The assessments were on 10 plants within a 0.25 m2 quadrat. The quadrat was randomly assigned along a randomly selected entry point transect line. The experiment near Tambo was set out (randomly selected 10 m2 plots) amongst existing vegetation. Grazing is the primary use of this land so the predominant introduced pasture species was C. ciliaris in conjunction with native pasture species, including A. elymoides. Other plant species within the trial areas were A. cambagei, Brachychiton rupestris (T. Mitch. ex Lindl.) K. Schum, Josephinia eugeniae F. Muell. and Aristida leptopoda Benth. (Henderson, 1997). The weather parameters at the time of application were similar to the Bacauldine temperature range and wind speed. Again Swiss- mex® compression sprayers were used with spot spray and hand boom attachments.

Figure 1. Ratings determining herbicide damage to Florestina tripteris. Rating 1= Dead, 2 = Total stem death, 3 = Top stem death, 4= Tip necrosis, 5 = Leaves yellowing, 6 = Normal. Treatments are as in Table 1.

Three assessments of herbicide effects were made in 2002 (Figure 1). A further four assessments were made after rain in 2003 to determine the residual effects of the herbicides on seedling emergence (Figure 2). These counts were obtained in 0.25 m2 quadrats as before. Treatments 10 and 13 were not considered when assessing the residual effects of herbicides. Plants were healthier at the Tambo site due to higher soil moisture, while plants at the Barcaldine site were moisture-stressed and sparse in distribution. The Barcaldine boom sprayed plants were up to 1 m in height and more mature, with most flowering and some exhibiting seed set. Although the overall density was less than at the Tambo site, plant numbers in many plots were high and these plants averaged 0.75 m in height.

Analysis The results were analysed with Systat 9 (Wilkinson, 1999a), using repeat measure multivariate analysis of variance (Wilkinson and Coward, 1999) and as outlined by (Sparkes and Panetta, 1997). A graphical presentation was used to differentiate between treatment and application method effects (Wilkinson, 1999b) (Figures 1 and 2). Readings from the 30

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Proceedings of the 21st Asian Pacific Weed Science Society Conference (Editors: B. Marambe, U.R. Sangakkara, W.A.J.M. De Costa, and A.S.K. Abeysekara), 2-6 October 2007, Colombo, Sri Lanka. assessed plants from within the datum areas for each cell were averaged for each assessment period and the smoothing applied utilized a distance-weighted least squares method (Wilkinson, 1999). The 30 assessed plants per assessable cell provided adequate numbers to represent the condition of treated F. tripteris in the two sites and meet the conditions for sampling normally distributed data. The data were combined for analysis (Figure 1). A multivariate repeat measure analysis was carried out with each of the treatment responses and site influences as the within subject variables, i.e. ratings at each of the assessments x treatment (Wilkinson and Coward, 1994). The metric, due to the uneven spread of weeks after application between assessments, was 1, 2 and 5 for herbicide efficacy and 1, 2, 4, and 12, for herbicide residual effects and was used to adjust F values for the error caused by non- systematic assessment. Post-hoc between-subject comparisons on the final results were moderated using Tukey adjustment (Wilkinson and Coward, 1994).

TREATMENT 9 4 15 7 22 100 90 80

70 %

60 s

50 e e

40 d

l i

. 30 n g

. 20 s ...... 10 ...... 0 2 6 20 24 5 100 90 . 80

70 %

60 s . 50 e . e . 40 d

. l i . . . 30 n

. . g ...... 20 s ...... 10 ...... 0 14 19 3 11 16 100 90 80

70 %

60 s . 50 e . . e

. . d . . 40

. l i . . . n ...... 30 ...... g ...... 20 s ...... 10 ...... 0 18 23 12 8 17 100 90 . 80

. 70 % . . . . . 60 s ...... 50 e . . . . e .

. d ...... 40 . . l . . . i .. . . n ...... 30 ...... g ...... 20 s ...... 10 ...... 0

3 3 3 4 3 3 3 4 _0 _0 _0 _0 _0 _0 _0 _0 21 1 25 _3 _4 _6 _3 _3 _4 _6 _3 6 2 9 4 6 2 9 4 100 . . . 90 . 80 .

. . % . 70 ...... 60 s . . . e

. . 50 e

. . . . d ...... 40 ... . l . . i

. . n ...... 30

. . g ...... 20 s ...... 10 ...... 0

3 3 3 4 3 3 3 4 3 3 3 4 _0 _0 _0 _0 _0 _0 _0 _0 _0 _0 _0 _0 _3 _4 _6 _3 _3 _4 _6 _3 _3 _4 _6 _3 6 2 9 4 6 2 9 4 6 2 9 4

Figure 1. Florestina tripteris seedling emergence following herbicide application. Ratings are % ground cover per 0.25 m2 quadrat. Treatments are as in Table 1.

Results

Herbicide efficacy There was a significant difference between the performance of the herbicides (MS = 5.44 df = 22, 446 F = 31.37 P <0.01). There was a steady quadratic movement from healthy pre- sprayed plants to plants that moved towards necrosis at the last inspection (Table 2).

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Assessments Mean Std. Error of p-value* 95% Confidence interval* over time difference difference 1 / 2 0.234 0.013 0.000 0.203 0.265 1 / 3 2.031 0.037 0.000 1.942 2.119 2 / 3 1.797 0.042 0.000 1.695 1.898 *Bonferroni correction for multiple comparisons was used.

The Tambo (Site 1) plots treated by the spot spray method produced more effective control compared to the Barcaldine plots (Site 2) treated using a hand boom (MS = 5.93 df = 1, 446 F = 34.22 p <0.01). However, the most effective first 12 treatments had similar effectiveness at both sites, whether applied by spot spraying or hand boom. The mortality of treated plants was higher for spot spraying possibly because plants were sprayed to run-off point. The best three foliar overall treatments were bromoxynil 200 g l-1 at 4 g a.i. l-1 (controlling 85% of weeds sprayed), 2,4-D acid 300 g l-1 at 17 g a.i. l-1 (controlling 75 % of weeds sprayed) and 2,4-D dimethylamine salt 500 g l-1 at 16 g a.i. l-1 (controlling 70% of weeds sprayed).

Residual seedling control A significant difference existed between the residual activity of the herbicides expressed as seedling emergence post application (Wilks' Lambda (counts over time x treatment) = 0.3 df = 66, 607 F = 4.6 p<0.01). All treatments produced residual effects that were different from the control except for treatment 8, the high rate of glyphosate (MS = 950.6, 80.4 df = 22,207, F = 11.8, p = 0.2) The best three treatments from the residual seedling control pilot trial at the Barcaldine site were clopyralid 300 g l-1 at 6 g a.i. l-1 (yielding 0.6% of seedling recruitment of untreated areas), and metsulfuron methyl 600 g kg-1 at 0.24 g a.i. l-1 (giving recruitment counts that were 30% of the untreated areas) and triclopyr ester 300 g l-1 at 4.2 g a.i. l-1 + picloram 100 g l-1 at 1.4 g a.i. l-1 (giving 80% of seedling recruitment of the untreated areas).

Discussion

The information from this trial led to a permit being issued by the Australian Pesticides and Veterinary Medicines Authority (APVMA) that was renewed in December 2006. The permit allows for the use of 400 ml 2,4-D amine (Amicide 500®) + 200 ml BS 1000® 100 l-1 water to be sprayed alone, 2-3 weeks after germinating rains, and before bud and flower stage. Once budding and flowering have begun, a tank mix of 200 ml 2,4-D amine (Amicide 500®) + 20 g metsulfuron methyl (Brush off®) + 200 ml BS 1000® 100 l-1 water will kill treated plants and reduce the number of germinants following the next rain. This tank mix can be sprayed only once for each cohort of weed emergence. This gives local authorities, landholders and conservation groups a tool to incorporate into control options and should reduce the spread of this plant. Prevention of F. tripteris establishment in pasture is a key factor in strategic control planning. Variables such as rainfall patterns, soil types, associated plant communities, grazing pressure and temperature are determinants in invasiveness of opportunistic weed species (Pressland, 1984). Sustained periods of drought and movement of stock and feed are factors in the establishment F. tripteris in new areas. F. tripteris will grow along road verges on unsealed roads, increasing the likelihood of establishment in new areas. Adaptive management techniques involving herbicide application should be instituted immediately

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Proceedings of the 21st Asian Pacific Weed Science Society Conference (Editors: B. Marambe, U.R. Sangakkara, W.A.J.M. De Costa, and A.S.K. Abeysekara), 2-6 October 2007, Colombo, Sri Lanka. after F. tripteris appears following rain events, as the rosette stage is more susceptible to herbicide treatment. Treatment at the rosette stage will prevent seed from being set and enable establishment of competitive pasture species. The rosette stage may last less than two weeks depending on how much follow up rainfall occurs. Florestina tripteris develops stands of higher density where soil disturbance has occurred, such as along the verges of roads and in consistently used stock routes. It was also noted that areas of heavily grazed pastures were more susceptible to invasion by F. tripteris. The road verges and stock route areas need to be surveyed and F. tripteris encountered needs to be treated with herbicide. Improved pasture management may assist in reducing the incidence of F. tripteris in grazing lands. Pot experimentation utilising controlled seed inputs will be necessary to confirm the herbicide residual effects observed in this field research.

Acknowledgments

We thank Damien Byrne the Land Protection Officer for the Central West region. We also thank John and Joss Chandler who allowed this work to be undertaken on there property. We acknowledge the effort of Stan and Donna Croker, Dougal Davidson, Shane Noon (Weed Officer Tambo Shire Council)., Will and Fia Hobbs from Tarrina and Col and Bev Bucknell from Woolga via Tambo, Queensland.

Literature cited

Australian Weeds Committee. 1979. Rating system for recording weed and/or crop population densities, plant damage, and tolerance of herbicide treatments. In: Guidelines for Field Evaluation of Herbicides, (ed Pesticide Section of the Australian Department of Primary Industry.). Australian Government Publishing Service, Canberra. Appendix 1, 1-6. Henderson, R.J. ed. 1997. Queensland Plants Names and Distribution. p. 99 Queensland Herbarium, Department of Environment, Mt.Cootha road, Toowoong, Brisbane. Milson, J. 1995. Plant Identification in the Arid Zone. Department of Primary Industries Information Series Q194035, Brisbane, Queensland. Pressland, A.J. 1984. Productivity and management of western Queensland's rangelands. Australian Rangeland Journal 6: 26-45. Sparkes, E.C., Panetta, F. D. 1997. Use of profile analysis of repeated measures in a herbicide trial on blue morning glory (Ipomoea indica) (Burm., Merrill). Plant Protection Quarterly 12: 133-137. Turner, B.L. 1963. Taxonomy of Florestina (Helenieae, Compositae) Brittonia 15: 27 - 46. Wilkinson, L., Coward, M. 1994. Analysis of Variance II In: Systat for Dos: Version 6 Advanced applications, Systat Inc., Evanston, Illinois. 305-334. Wilkinson, L. 1999a. Scatterplots. In: Systat 9 Graphics, (ed Pechnyo M.). SPSS Inc., Chicago. 143-153. Wilkinson, L. 1999b. The Grammar of Graphics. pp. 231-300 Springer, New York. Wilkinson, L., Coward, M. 1999. Linear Models II: Analysis of Variance In: SYSTAT 9, Statistics I, (ed Clarkson K.). SPSS Inc, Chicago. I-43, 1-485.

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