Biological Control of Grass Weeds in Australia

62 Plant Protection Quarterly VOI.5(2) 1990 son 1972, Savile 1979, 1987). For these rea Biological control of grass weeds in Australia: sons the tribe Stipeae is placed as belonging an appraisal to both Pooideae and Arundinoideae in Table 1 and this combined relation would have to be taken into account when consider A.J. Wapshere, CSIRO Division of Entomology, GPO Box 1700, Canberra, ACT ing biological control of grasses in this tribe. 2601, Australia. The weeds Hordeum spp. and Agropyron spp. are the only ones related tribally or more Summary closely to the important crop grasses, Hor Two biological control methods are consid iii) if not and potential agents occur in the deum spp. (barley), Triticum spp. (wheat) ered for the more than 250 grasses regarded grass weed's native range, whether they and Secale cereale L (rye) (Table 1). A as weeds in Australia, 170 of which, includ have sufficient host restriction to be in group of andropogonid weeds are related ing the most important, are of exotic origin. troduced into Australia. tribally to Zea mays L (maize), Sorghum bi 1. Inundative or bioherbicidal control color (L) Moench (sorghum) and Sac· where agents already present in Australia, Introduction charum officinarum L (sugar cane). Weeds probably fungi, would be used like herbi The possibility of biologically controlling in the genera Aira. Aven~ An-henalherum. cides. Mostly it is grass weeds important in grasses which have become weeds in Austra Holcus, Lophochloa, Molineriella are sub crops which would repay such an approach lia has been discounted by commentators on tribally or more closely related to the impor but only a few of these have 8 range orfuogi the subject for some considerable time. This tant crop grass Avena sativa L (oats) and already infesting them in Australia. has been due mainly to the close relation of many other weedy grass genera are tribally 2. Classical or inoculative control, where these weeds to cereal crops and pasture related to that crop (Table 1). Weeds in the agents from the home range of the grass grasses. This paper discusses the biological genera Avena, Echinochloa, Hordeum, would be introduced into Australia. Only a control of grass weeds in Australia in the light Oryza, Sorghum, Pennisetum, Panicum and few types of agents, notably gall makers and of recent developments in the SUbject and Setaria are closely related generically to the smut fungi, have sufficient specificity to be indicates which grass weeds would be most important crop grasses Avena saliva (oats), considered for introduction and then only if susceptible to the different methods of bio Echinochloa spp. (Siberian and Japanese the grass weeds are not related generically logical control. millets), Hordewn vulgare L (barley), Oryza to crop or pasture/lawn grasses. sativa L (rice), Sorghum bicolor (sorghum), The taxonomic relations of the grass The Australian Grass Weeds Pennisetum glaucum (L) R. Br. (pearl weeds to crop and pasture/lawn grasses are More than 250 members of the grass family millet), Panicum miliaceum L. (proso) and detailed. Conflicts of interest that arise be Poaceae (; Gramineae) are regarded as Setaria italica (L) Beauv. (foxtail millet) reo cause many grasses either are both crop weeds either in standard Australian weed spectively. weeds and valuable pasture or lawn grasses texts and lists (Auld and Medd 1987, Klein Table 2 lists the weedy grasses which are or are generically related to them, are schmidt and Jobnson 1977, Lamp and Collet closely related (uG" ; same genus) to crop listed. 1979, Parsons 1973, Swarbrick 1983, Whittet or pasture/lawn grasses and those cases Examples are given of the possible use of 1968, Wilding et aL 1986) or are aquatic where the same grass ("S" ; same species) is the two methods as follows: weeds (Mitchell 1978, Sainty and Jacobs both a weed in some situations (i.e. crops) Avena spp., Hordeum spp and Echinochloa 1981) or have herbicide recommendations and an important component of native or spp. because of their close relation to crop for their control (Swarbrick 1984). Of these, improved pastures are also indicated based grasses, Stipa spp. because they are native 170 species, including most of the important on comments on the pasture importance of pasture grasses and Cynodon dacJylon be weeds, are of exotic origin. grasses in Whittet (1969), Reid (1981), Bur· cause both a lawn grass but also a crop The taxonomic relations of Australian bidge (1966, 1968, 1970, 1984), Lazarides weed, could only be controlled using agents grass weeds and crop grasses are based on (1970), Wheeler et al (1982), and Tothill and already present in Australia inundatively. Watson and Dallwitz (1985) and Clayton and Hacker (1983). The biological control of Bromus spp. which could also be the subject Renvoize (1986) (Table 1). There are only these grasses could be compromised bY con of bioherbicidal control, Holcus s pp. and, in two major differences between their classifi flicts of interest between land users wishing particular, Phragmites spp. which has a cations. One, the separation of the centoth to maintain these grasses in pasture or lawns large number of apparently specific agents ecoid group as a separate sub-family in Clay or wishing to grow related crops and others in its Old World home range, could possibly ton and Renvoize (1986) and its inclusion as seeking to control the same or closely related be controlled by the classical introduction a tribe of the Oryzaneae within the sub·fam· grasses biologically. Indeed, many grasses of exotic agents. Sorghum hakpense could ily Bambusoideae bY Watson and Dallwitz would be considered valuable fodder for have rhizome-feeding agents introduced to (1985), is not relevant here as there are no stock but weeds when that same land was control it but not agents attacking aerial Australian weeds, crops or pasture grasses in ploughed for crops bY the same farmer. parts of the plant which would infest crop that centothecoid group. The other is the Table 3 lists the grass weeds for which there sorghum. Eleusine indica could possibly be placement of the tribe Stipeae in the sub would not be economic conflicts of interest in controlled using both methods. Nassella family Arundinoideae by Watson and Australia although some are regarded as trichowma is probably too closely related to Dallwitz (1985) instead of in the sub·family minor lawn or decorative garden plants and native Stipa spp. to allow the introduction of Pooideae bY Clayton and Renvoize (1986). others such asAmmophila arenaria (L.) Link agents. Recent discussions on the taxonomic posi are used for sand dune stabilization. It is concluded that each genus of weedy tion of the Stipeae either concur with Watson grasses and in some cases each weedy grass and Dallwitz (1985) (Watson et aL 1985, Biological Control Methods species has to be considered individually Barkworth and Everett 1986) or suggest that Two types of biological control will be consid and the type of biological control selected this tribe is basal to the Pooideae rather than ered here. according to the following features:- belonging to it (Kellogg and campbell 1986). 1. Inundative or bioherbicidal control, where i) whether the weedy grass is related to crop The evolutionary position of both the rust an agent is artificially increased, bulked up, and/or pasture grasses, fungi and sm ut fungi infesting Stipeae sug and applied bY the land user in the same ii) wheth-;r a pool of potential agents occurs gests that this tribe is intermediate between manner as a chemical herbicide. Disease in Australia already, the Arundinoideae and the Pooideae (Wat- organisms such as fungi and nematodes Plant Protection Quarterly Vot.5(2) 1990 63 Table 1. Taxonomic position of Australian grass weed genera TRIBE TRITICEAE Hordeum, Agropyron, CROPS; Triticum, Secale Position of grass crop genera indicated where different from weed (2 tribes in Triticanae (W. & D.)) genera. Based on Clayton and Renvoize (1986) (c. & R.), relevant SUB-FAMILY CHLORlDOlDEAE differences between them and Watson and Dallwitz (1985) (W. & D.) TRIBE ERAGROSTIDEAE as indicated. SUB-TRIBE ELEUSININAE Leplochloa, Dinebra, Eragrostis, FAMILY POACEAE (= GRAMINEAE) Triraphis, Eleusine, SUB-FAMILY BAMBUSOlDEAE Dactyloctenium, Dip/aehne TRIBE BAMBUSEAE SUB-TRIBE SPOROBOLINAE SUB-TRIBE ARUNDINARIlNAE Sparobolus Anmdinaria TRIBE CYNODONTEAE SUB-TRIBE BAMBUSINAE SUB-TRIBE CHLORIDINAE Bamb"sa, Phyllostachys Chloris, Brachyachne, Sparlina, Cynodon TRIBE ORYZEAE SUB-TRIBE ZOYSIlNAE Oryza, Leersia Tragus, Perotis TRIBE EHRHARTEAE (all above chloridoid sUb-tribes Ehrharta combined (W. & D.)) SUB-FAMILY ARUNDINOlDEAE SUB-FAMILY PANICOIDEAE TRIBE ARUNDINEAE TRIBEPANICEAE Danthonia (= Rylidosperma). Cortaderia, SUB-TRIBE SETARIINAE (both in Dantbonieae, (W. & D. )),Arnndo, Pan;cum , Echinochloa , Brachiaria, Urochloa , Phragmites Paspalum , Axonopus I Setaria , Paspalidium , TRIBE ARISTIDEAE Eriochloa, Stenotaphrum Aristida SUB-TRIBE MELINIDINAE SUB-FAMILIES ARUNDINOJDEAE/POOlDEAE Rhynchelytrnm, Melinis TRIBE STIPEAE SUB-TRIBE DIGiTARIINAE Stipa, Nassella, Oryzopsis (= Piptathenlm) Digilaria (all 3 in Stipeae, Arundinoideae (W. & D. ) SUB-TRIBE CENCHRINAE but all 3 in Stipeae, Pooideae (c. & R. )) Cenchrns, Pennisetum SUB-FAMILY POOlDEAE TRIBE ANDROPOGONEAE TRIBEPOEAE SUB-TRIBE SACCHARINAE Fesluca, Lolium, Vulpia, Psi/urns, Cynosurns. Imperata, CROP; Saccharum Lamarelda, Poa, Desmazeria, (= Catapadiwn 1 SUB-TRIBE SORGHINAE Dactylis, Brim Sorghum, Dichanlhillm , Chrysopagon, TRIBE

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