Literature review: Impact of Chilean needle grass ... - Weeds Australia

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neesiana seeds are similar to those of some of the more robust seeded Austrostipa spp. which McBarron (1976 p. 135) considered to be “undoubtedly ... the major cause of seed troubles for livestock, especially sheep in New South Wales”. These Austrostipa spp. are commonly cited as one of the main undesirable attributes of native pastures, requiring timely destocking to avoid problems (Garden et al. 2000). Seeds of Austrostipa spp. penetrate the eyes, mouthparts (Whittet 1969), skin and flesh (Mulham and Moore 1970) of sheep. “Wrinkled, long-woolled and young sheep are particularly susceptible ... the wrinkles and long wool collecting more of the seed, and the softer skin of young sheep allowing easier and deeper penetration. Severe damage to the eyes, jaws and feet can be caused by the seeds, which have also been known to penetrate the abdomen and internal organs ... in extreme cases blindness, lameness, fever and death can result” (Mulham and Moore 1970 p. 105). Austrostipa and Aristida spp. are the most common contributors to ‘vegetable fault’ (plant contamination) of wool in Australia (Grice 1993). N. neesiana seeds are an irritant of skin (Wells et al. 1986) and “readily bore into the skins of animals, causing painful wounds” (Hayward and Druce 1919). Irritation of livestock by attached seeds causes discomfort and loss of condition (Wheeler et al. 1990). Lambs appear to be particularly susceptible to eye injury (Bourdôt and Ryde 1986).. Infestation of livestock with seeds may be exacerbated by rain, as happens with Austrostipa (McBarron 1976). The hides of cattle are too thick for the seed to penetrate (Gardener et al. 1996b) but cattle may suffer injuries to the mouth and intestinal tract. The seeds “cause discomfort” for dogs and humans (Liebert 1996), and can injure pet animals (Snell et al. 2007) and could be expected to cause a range of serious medical problems based on their similarity to other stipoid seeds (see McBarron 1976). Awned seeds in general can readily penetrate the soft tissue of the buccal and gastrointestinal tracts, producing inflammation, abcesseses and tooth and gum disease (McBarron 1976). They may pass through the skin into muscle and can occasionally penetrate internal organs, potentially causing fatal injuries (McBarron 1976). However penetration of skin, carcases and eyes by N. neesiana seeds is rare on the northern tablelands of NSW (Cook 1999). The seeds are a contaminant of wool (Hayward and Druce 1919, Wells et al. 1986, Auckland Regional Council 2002). The halflife of seeds in the coats of sheep exposed to seeding plants for 17 days and then removed from exposure was measured at 7.5 days, with nearly half the seed remaining embedded after 100 days and only very slow subsequent seed loss (Gardener et al. 2003a). Upon removal of exposure, half the seeds on sheep had the callus embedded in the skin, but this reduced to 5% after 35 days, and few seed penetrated through the skin into flesh (Gardener et al. 2003a). The seeds damage pelts, and reduce the quality of carcases and hides (Bourdôt and Ryde 1986, Bourdôt and Hurrell 1992, Slay 2002, Auckland Regional Council 2002). In the context of livestock grazing N. neesiana is a ‘conflict of interest’ species (Grice 2004b) because it is a valuable fodder for much of the year (Gardener 1998, Grech et al. 2004, Grech 2007a). Although it has harsh, often hairy leaves and tall course culms (Connor et al. 1993), it is considered to produce moderate quality, palatable forage during winter and early spring (Slay 2002c) and to be of “modest” grazing value (Connor et al. 1993). In Argentina “it produces fairly good fodder” (Hayward and Druce 1919 p. 228) and is considered one of the most important winter grazing species, valued because of its perenniality, persistence, long life and good quality feed with relatively high crude protein levels in the young foliage (Gardener 1996, Gardener et al. 1999). Its undesirability as a pasture species results not only from the problems caused by the seeds but from the rapid reduction in foliage that accompanies the production of large numbers of unpalatable flowering stems in late spring and summer, which results in a large seasonal reduction in carrying capacity at a critical time of year. Livestock avoid the plant in its reproductive phase, so it gradually displaces more valuable pasture grasses (McWhirter et al. 2006). Its feed value (crude protein and digestibility) is less than that of deliberately grown pasture grasses at the same stage of growth (Gardener et al. 1996b, Gardener 1998, Cook 1999). It generally has a lower feed value than the widely cultivated, moderate feed value Dactylis glomerata and is less reponsive to applications of N fertiliser (Grech et al. 2004, Gaur et al. 2005). But it responds well to clipping (as a simulation of grazing), the regrowth sward after clipping having significantly higher crude protein, metabolisable energy and digestible dry matter contents than growth in unclipped swards (Grech et al. 2004). Fertilisation and clipping can be used to improve its usefulness as fodder (Grech et al. 2004) but grazing can promote its dominance when pasturage consists of more palatable species (Liebert 1996, Gardener 1998). N. neesiana is undesirable also because it can contaminate other agricultural produce, including hay (Frederick 2002). Increased fire risk has rarely been seen as a problem. Bartley et al. (1990) argued that “the greater height and density” of N. neesiana swards at Laverton North Grassland Reserve presented “a much greater fire hazard than native grasses”. According to Liebert (1996 p. 9): “Regional fire authorities recognise the fire risk ... and consequently slash swards from November to December”. However, comparative biomass production and breakdown assessments appear to be lacking and there appears to have been no proper evaluation of fire risk, which should involve comparisons with alternative vegetation states. All plants deplete soil moisture and the amounts of water used at particular times may have implications for co-occuring species or have a wider ecological impact. Slay (2001) observed that soil moisture in early January under a dense ungrazed sward was 20.8%, while where the sward had been sprayed with glyphosate at flowering time it was 26.6% due to reduced transpiration and the reduction of evaporation due to dead thatch. Infestations in T. triandra grasslands presumably deplete soil moisture in spring and early summer, at the same time as the inter-tussock species are growing and before the main growing period of T. triandra. The overall effect could be a premature drying-out of the grassland landscape. Like other weeds N. neesiana can have beneficial impacts, although apart from its fodder value, these have hardly ever been recorded in its invasive range. Slay (2002a) noted that well stablished populations can provide erosion control on steep land. Control and management N. neesiana is difficult to control and according to Gardener and Sindel (1998 p. 78) there is “overwhelming evidence” that it is “almost impossible to eradicate” because of the difficulty of killing mature plants, the size and longevity of the soil seed bank and the production of basal cleistogenes. Gardener et al. (1996a p. 243) considered there then existed “no widely successful management techniques which result in the eradication or long term reduction”, while Gardener et al. (2003a p. 613) judged that “chemical and mechanical control have had little success to date, at best temporarily slowing its spread”. Slay (2002c p. 24) considered that the “overall tenacity” of Chilean needle grass made it “an extremely stubborn weed to manage and control”. He 68
also noted that despite a wide range of control measures applied over a long period, land managers in New Zealand had reported “no success in terms of eradication” (Slay 2002a p. 7). Kirkpatrick et al. (1995 p. 35) claimed that it “seems impossible to control in its early invasive stage without causing great damage to native vegetation”. Liebert (1996) also considered it difficult to manage. Recent overviews of control techniques include Slay (2002a), Michelmore (2003) and Snell et al. (2007) the latter providing the most comprehensive details. An initial requirement in all management plans, but one often neglected, is to obtain a good representation of the plant’s distribution and the status of populations. Thus the ACT Weeds Working Group (2002) listed survey and monitoring as the first priority in their management plan, and Muyt (2005), for example, undertook one such survey. Site assessment should include mapping and density assessment (Snell et al. 2007). Targeted surveys, a public reporting mechanism and mapping of infestations have been identified as important elements in a regional management approach (ACT Weeds Working Group 2002). The critical foci of management activity is on techniques for depleting the soil seed bank by controlling seed input through mowing, herbicide application or cultivation/cropping (Bourdôt 1988, Bourdôt and Hurrell 1992, Slay 1992, Duncan 1993), slashing, burning or grazing (Slay 2002c, Beames et al. 2005, Grech 2007a, Snell et al. 2007), on reducing recruitment and density of established plants (Beames et al. 2005), along with prevention of spread (Bourdôt 1988, Frederick 2002, DPIW 2007, Snell et al. 2007). In pasture situations where eradication is unlikely, the emphasis has been on the development of methods for better utilisation, including strategic stocking (Duncan 1993, Gardener et al. 1999, McWhirter et al. 2006, Grech 2007a, Snell et al. 2007), and on agronomic techniques to maximise production of palatable foliage and minimise production of flowering culms and seed, including spray-topping or wick wiping, fertiliser application and intensive grazing (Slay 2002c, Grech et al. 2004, Grech 2007a). Long term management requires replacement by competitive species in pastures (Slay 2002c, Grech 2007a) and non-agricultural areas including native grasslands (Mason and Hocking 2002, Hocking 2005b) or conversion to another land use such as cropping or forestry (Slay 2002c). Morfe et al. (2003) presented a cost-benefit analysis of alternative management strategies for three different rates-of-spread scenarios. They considered it realistic to reduce infestations by 99% over 10 years only for infestations of less than 10 ha, and to reduce infestations by 90% for areas up to 500 ha. The vast majority of information on N. neesiana control and management relates to agricultural areas (e.g. Bourdôt 1988, Bourdôt and Ryde 1986 1987a 1987b, Duncan 1993, Gardener 1998, Gardener et al. 1996a 1996b 2005, Grech 2007a, Grech et al. 2004 2005 2007, McWhirter et al. 2006, Slay 2001 2002b 2002c, Snell et al. 2007) and the National Strategic Plan for N. neesiana (ARMCANZ et al. 2001) did not detail an integrated management approach for native grasslands (Downey and Cherry 2005). To date the best guide for N. neesiana management in grasslands and grassy woodlands is that of Beames et al. (2005), although Snell et al. (2007) provided useful guidance. Various options for conservation areas have been suggested, with the aim of generally reducing populations while maintaining existing native species and managing to advantage the native plants (Bedggood and Moerkerk 2002). Spot spraying is the favoured method of eradication, using non-persistent herbicides (Beames et al. 2005). Snell et al. (2007) recommended use of flupropanate, but warned that it can be very damaging to many native grass species. Regular biomass reduction by burning or grazing is widely used in the south-eastern Australian grasslands (see below under grassland management) to maintain plant diversity and has been suggested as useful in reducing N. neesiana biomass and fuel load (Bedggood and Moerkerk 2002). Use of fire to reduce seeding and destroy fallen seed has also been recommended (Snell et al. 2007). Resowing with native grasses is recommended when more than three tussocks are removed or an area >0.5 m diameter is treated, either with the ‘spray and hay’ method (see below) or other techniques (Bedggood and Moerkerk 2002, Snell et al. 2007). Annual grazing and burning of native pasture was listed as a successful management option by Bedggood and Moerkerk (2002). The pasture is grazed heavily until N. neesiana enters the reproductive phase, stock are then removed and the area is burnt late, i.e. in autumn or winter, so as not to kill T. triandra. Hand removal Isolated plants and small infestations can be grubbed out (Bourdôt 1988), although Slay (2002a) considered this impractical. Liebert (1996) recommended using a mattock. Slay (2002c) recommended digging to at least 15 cm depth and 40 cm diameter and disposal of bagged material by incineration or deep burial. Snell et al. (2007) considered manual chipping a preferred method because the potential for regeneration from basal cleistogenes is eliminated if chipped plants are removed from the site. Herbicides According to Slay (2002a), who reviewed herbicidal management of N. neesiana, twenty five herbicides have been used in documented control attempts. The most frequently used in Australia have been glyphosate, flupropanate, 2,2-DPA, atrazine, hexazinone and simazine; the first two being the main chemicals used in Australian native grasslands (Lunt and Morgan 2000). The herbicides with soil residual properties, particularly flupropanate, are valued for the ability to prevent seedling emergence. Use of herbicides on N. neesiana in Australia was severely inhibited for many years by the failure of herbicide manufacturers and retailers to include the plant on herbicide labels. None of the chemicals mentioned by Duncan (1993) were at the time registered for use against N. neesiana in Australia, nor were those mentionded by Liebert (1996). This situation remained unchanged in October 2004, although State Government agencies, funded by the Australian Government, were undertaking detailed trials in order to achieve appropriate herbicide registrations (Iaconis 2004). Thus chemical control relied on ‘off-label’ use for a very long period. Lack of label recommendations in some cases meant that State Government officers could provide no recommendations or advice on N. neesiana herbicidal management (Iaconis 2004). In Victoria, a government ‘Code of Practice for Provision of Chemical Advice to Clients’ (DNRE 2000) prohibited any mention of off-label uses by government officers involved in recommending herbicides for weed control. Interpretation of the Victorian Code was complicated by the listing of broad weed categories such as ‘perennial grasses’ on some herbicide labels. In New South Wales and the Australian Capital Territory label directions were able to be overridden byAustralian Pesticides and Veterinary Medicines Authority (APVMA) permits (Michelmore 2003). NSW recommendations relied on a series of temporary APVMA permits, for pasture spraying with glyphosate and flupropanate, spray-topping with glyphosate, and use of fluazifop-P in legume pasture and lucerne (listed in 69
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Literature review: Impact of Chilea
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Fire 49 Other disturbances 50 Shade
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Conventions and standards Botanical
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neesiana appears to be a habitat ge
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population densities of existing sp
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elated plants have similar defences
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For invasion to occur there must be
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As yet there appears to be no evide
Page 17 and 18: experimental manipulation of specie
Page 19 and 20: species tend to be those which tran
Page 21 and 22: Taxonomy and nomenclature Stipeae N
Page 23 and 24: Vernacular names ‘Needlegrass’
Page 25 and 26: to Bouchenak-Khelladi et al. 2009).
Page 27 and 28: 1 m (Walsh 1994), ca. 90 cm (Verloo
Page 29 and 30: Figure 2. Anatomy of the seed of N.
Page 31 and 32: are the seeds larger/smaller, longe
Page 33 and 34: also based on a misunderstanding of
Page 35 and 36: Table 2. Modified Feekes Scale for
Page 37 and 38: Argentina, in the provinces of Chac
Page 39 and 40: Figure 3. Recorded distribution of
Page 41 and 42: 1994). Only 3 of 186 exotic grasses
Page 43 and 44: According to Morfe et al. (2003) th
Page 45 and 46: populations have been found in the
Page 47 and 48: (Honaine et al. 2006). The flechill
Page 49 and 50: In Australia the altitudinal range
Page 51 and 52: Proximity to urban development appe
Page 53 and 54: In the southern Brazilian campos of
Page 55 and 56: arundinacea (Gardener et al. 2005).
Page 57 and 58: al. 2008). Cues for masting may be
Page 59 and 60: Approximately 200 alien grass speci
Page 61 and 62: Dispersal of seed in contaminated s
Page 63 and 64: In New Zealand, Hurrell et al. (199
Page 65 and 66: No emergence was observed in undist
Page 67: and high impact (“ability to caus
Page 71 and 72: a small reduction in seedhead produ
Page 73 and 74: Slashing and mowing Slashing can re
Page 75 and 76: Themeda re-establishment McDougall
Page 77 and 78: species (Lawton and Schroder 1977 p
Page 79 and 80: y increased importance of ant grani
Page 81 and 82: BIODIVERSITY “Biodiversity ... on
Page 83 and 84: According to Woods (1997 p. 61) “
Page 85 and 86: 2004, Richardson and van Wilgen 200
Page 87 and 88: negative depending on the particula
Page 89 and 90: Competition with native plants Comp
Page 91 and 92: asexual seed production, so local f
Page 93 and 94: GRASSLANDS Grasses: “... the most
Page 95 and 96: susceptible to N. neesiana invasion
Page 97 and 98: Floristic composition, vegetation s
Page 99 and 100: proportion of the flora then presen
Page 101 and 102: tussock space (Stuwe and Parsons 19
Page 103 and 104: Like vascular plant diversity, comm
Page 105 and 106: Opinions differ on the nature and i
Page 107 and 108: Species Common Name Family Aust ACT
Page 109 and 110: in shifting the distribution, exten
Page 111 and 112: of these systems is largely explain
Page 113 and 114: pasture. The least understood trans
Page 115 and 116: tend to benefit more from relaxed c
Page 117 and 118: Bovids crop their food between the
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are therefore less likely to distur
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esult in a “short-term flush” o
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Fire effects on weeds Moore (1993 p
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Table 8. Typical nutrient levels in
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grasses produced sigificantly more
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Fossorial vertebrates are or were o
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(Rosengren 1999). Approximately one
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Table 12. Areal extent and conserva
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Foreman (1997) investigated the eff
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Willis (1964) considered that the f
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Austrostipa-Enneapogon) from around
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Woodlands and New England Grassy Wo
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Thylogale billardierii), Peramelida
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Its original habitat on the mainlan
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Table 17. Endangered reptile specie
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equirement, but unlike plants and v
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e assigned the same biodiversity sc
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Nematodes are mostly minute animals
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found in all mainland states, O. co
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Keyacris scurra, Melbourne (1993) o
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was once widespread in south- easte
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eing sluggish and wingless, and exi
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estoration and, if Australia follow
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close to the plant are able to bury
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Species *Chirothrips mexicanus Craw
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Table A2.1 (continued) Species Life
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Table A2.1 (continued) Species *Het
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Page 175 and 176:
Page 177 and 178:
Nematodes of grasses and grasslands
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REFERENCES Aceñolaza, F.G. (2004)
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Benson, D. and McDougall, L. (2005)
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Chan, C.W. (1980) Natural grassland
Page 185 and 186:
DNRE (Department of Natural Resourc
Page 187 and 188:
Fuhrer, B. (1993) A Field Companion
Page 189 and 190:
Groves, R.H. and Whalley, R.D.B. (2
Page 191 and 192:
Iaconis, L. (2004) Chilean needle g
Page 193 and 194:
Levine, J.M., Adler, P.B. and Yelen
Page 195 and 196:
McDougall, K.L. (1987) Sites of Bot
Page 197 and 198:
Morfe, T.A., McLaren, D.A. and Weis
Page 199 and 200:
Perelman, S.B., León, R.J.C. and O
Page 201 and 202:
Saunders, D.A. (1999) Biodiversity
Page 203 and 204:
Thellung, A. (1912) La flore advent
Page 205 and 206:
Weiss, J. and McLaren, D. (2002) Vi
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