Asparagus weeds - Weeds Australia

unoff from urban areas. Basic managementprinciples include:• Manage site to improve native species diversity.• Keep soil carbon levels high (e.g. establishnative perennials to reduce nitrate levels). Theaddition of carbon and burning can reduceinorganic nitrogen and may reduce the growthof non-native ground layer species relative tonative species.• Maintain ground cover – don’t create opportunitiesfor weed invasion, but some bare ground isneeded to allow native forbs to establish.• Prevent grazing of native seedlings and sensitivespecies.• Use herbicide sparingly.Stock management can be an importantconsideration in modified environments:• Intermittent grazing regimes can maintainor improve condition of grassy woodlandecosystems without causing too muchcompaction of the soil.• Time grazing periods to avoid native floweringand seed set (regionally specific).• Grazing pressure can support asparagus weedmanagement. For example, sheep will grazecommon bridal creeper and A. declinatuskeeping the plants at low levels in grazed areas.Integrated fire and herbicide control may beeffective in managing asparagus weeds in modifiedenvironments:• Geophytes (perennial plants with undergroundstorage organs, such as Asparagus spp.) arereasonably fire tolerant due to their habitof dying back to the storage organ duringsummer. However, following a summer fire,these weeds will often emerge in autumn, priorto regeneration of native vegetation, makingherbicide control easier and more effective.• Control of established populations andprevention of seed production can beachievable under these conditions.Asparagus declinatus dominating understorey vegetationNote: For many asparagus species the seedwill germinate or decay within two yearsand vegetative material (rhizomes) canoften have greater persistence in the soilthan seed. Fire is the major disturbancein the Mediterranean ecosystems of SouthAfrica where 95% of Australia’s geophyteweeds originate. Consequently many haveevolved life history traits that are stronglytied to recurrent fire. Dying back to anunderground storage organ over the longdry summer is an extremely effective wayof surviving fire. When dormant in summer,most geophyte weeds will probably surviveall but the very hottest fires.Herbicide selection and application approach isimportant in woodland environments:• Glyphosate (a non-selective herbicide) is usefulfor removing dense weed monocultures indisturbed environments.• Where asparagus weeds are growing closelyamongst native vegetation, non-selectiveherbicides can cause unacceptable levels ofoff-target damage unless targeted applicationtechniques are used (e.g. cut-paint, gouge-paint).• Residual herbicides, such as metsulfuronmethyl,can cause native plant death at very lowconcentrations and can remain active in the soilfor several months following application.See case study for managing Western Cape bridalcreeper in modified eucalypt woodland of theMount Lofty Ranges on page 95.Shauna Potter76