Ground Cover Supplement : GC Supplement - Pastures
GROUND COVER PASTURES 13 LUCERNE Pegasis -- a new lucerne for cropping rotations PROJECT: BREEDING IMPROVED LUCERNES FOR CROPPING SYSTEMS IN EASTERN AUSTRALIA, PHASE II. TIM O'BRIEN weeds controlled in subclover-based pastures, results are not directly transferable to other pasture legume species. A useful summary (11 trials) of herbage pro- duction following a wide range of herbicide treatments was presented in the 2006 DAFWA Crop Updates (p111) for French serradella (CadizA), yellow serradella (CharanoA), biserrula (Casbah), gland clover (Prima), balansa clover (FrontierA), arrowleaf clover (CefaluA), subclover (Dalkeith), burr medics (Santiago, CavalierA, ScimitarA) and strand medic (HeraldA). n CadizA French serradella displayed useful tolerance to Broadstrike®, Spinnaker®, Raptor® and bromoxynil. However, it was very sensitive to the less expensive herbicide options such as MCPA, Tigrex® and sima- zine, phenoxy herbicides and mixtures containing diu- ron. It was also observed that in general the response of hardseeded French serradella cultivars MarguritaA and EricaA and yellow serradella cultivars SantoriniA, CharanoA and YelbiniA is similar to CadizA. n Casbah biserrula appears to be sensitive to most of the herbicide options tested, and was particularly sensitive to Broadstrike® but has consistently shown reasonable tolerance to bromoxynil. n Varieties of burr, barrel, strand and sphere medic showed good tolerance to Broadstrike® and Dual Gold® but were very sensitive to Spinnaker® (PSPE), bromoxynil, MCPA and 2,4-D. However, some varia- tion in herbicide response was found between species. For instance, Orion sphere medic appeared sensitive to 2,4-DB and was badly damaged by Raptor®. n FrontierA balansa clover and Prima gland clover showed good tolerance to Spinnaker®, Raptor®, Broadstrike® and 2,4-DB. However, both were very sensitive to Igran®, 2,4-D and mixtures containing diuron. FrontierA was tolerant of MCPA but showed sensitivity to bromoxynil and Dual Gold®. n Even though spraytopping with Gramoxone® is gen- erally safe on subclover, this treatment resulted in a significant reduction in seed set for Hykon rose clo- ver, Prima gland clover, FrontierA balansa clover and Orion sphere medic. In conclusion, the impact of herbicides on pasture performance should be weighed against the impact of weed competition and weed seedset, in the absence of herbicide use, on pasture production and subsequent crop/pasture performance. Dr Clinton Revell, David Ferris and Christiaan Valentine are pasture research officers, Department of Agriculture and Food, Western Australia. GRDC Research Code DAW00031 More information: Details on individual trials can be obtained from Crop Update articles (1998, 2001, 2002, 2004, 2005, 2006) (see Weeds > Herbicide Tolerance) which are available on the Department of Agriculture and Food WA website, www.agric.wa.gov.au It is important to note that many of the treatments reported are not registered, so farmers and agronomists are advised not to make any decision solely on the basis of these experimental results. THE BENEFITS OF lucerne in grazing situations are widely recognised. Lucerne’s capacity to produce high- quality feed, its drought tolerance, responsiveness to rain after drought and its contribution to grazing value have all combined to make it ‘king of the fodders’. The potential of lucerne as a legume-ley in cropping rotations has more recently been recognised. Lucerne’s ability to fix nitrogen and return organic matter helps restore the fertility of cropping soils. A legume-ley pro- vides a ‘break crop’, reducing yield losses that can arise from pests and disease in monoculture cropping. Competitive lucerne stands also reduce weed burdens and can help delay the onset of herbicide resistance. In addition, the deep root system of lucerne can draw down excess water in the soil profile and ameliorate the onset of waterlogging, salinisation and acidification of crop- ping country. These benefits result in increased grain yield, improved grain quality, improved environmental sustainability and greater whole-farm profitability. The NSW Department of Primary Industries (DPI) lucerne breeding program, with funding provided by the GRDC, is developing lucerne varieties specifically for use in short-term cropping rotations. An outcome of this breeding work has been the development of the recently released variety PegasisA – a new lucerne developed exclusively for cropping systems. The breed- ing process for PegasisA involved the selection of elite populations with high herbage production, robust persistence, high winter activity and high pest and dis- ease resistance. PegasisA has demonstrated outstanding performance in different field trials conducted across NSW by NSW DPI, and also in trials conducted in PegasisA is a new lucerne specifically developed for cropping systems.
GC Supplement - Growers sharing knowledge
GC Supplement - Subsoil constraints