Grassland Management

Although Flora Victoria is heavily involved in harvesting and sowing native grass seed, a large proportion of our work involves the management of weeds in remnant grasslands. Flora Victoria has over ten years of experience managing weeds in grassland remnants and our methods of weed control have become an important tool in the restoration of some significant grasslands that are being invaded by weeds like Phalaris aquatica, a weed considered by many as almost impossible to eradicate without causing severe off target damage. Our experience managing weeds in seed production areas has also greatly enhanced our weed control capabilities in remnant grasslands and some of our methods are outlined below.

Flora Victoria employees are trained in precision spot spraying. This method takes spot spraying to its full potential and although time consuming, it is the only current method capable of controlling many weeds in floristically diverse grasslands. This style of spraying is only possible with a backpack sprayer, which also has the benefit of keeping vehicles and heavy machinery out of grassland remnants.

Repeated spraying of Phalaris aquatica in this grassland shows that the native grasses will re-establish if there is a source of seed.

The same area a year later. Danthonia has been able to regenerate naturally and displace the Phalaris.

Phalaris aquatica has been sprayed from part of this grassland leaving any remnant native grass.

Even endangered species like Pimelea spinescens can be saved from weed invasion if the spray operators are skilled enough.

This area is covered with Phalaris aquatica which is taking over part of a grassland and threatening the Pimelea spinescens plant in the middle of the picture.

After spraying, the Phalaris aquatica has gone. The Pimelea spinescens and native grasses have been left. Over the next year this area will be re-colonised by native grasses.

After three years of weed control the area is blending back into the grassland.

After four years it is almost impossible to tell this area had been dominated by Phalaris aquatica. The Pimelea spinescens has also produced some seedlings.

Five years later in November 2010, the Pimelea spinescens is lost among the native grass.

Flora Victoria also has many other weed control strategies that can be used in grassland remnants that don’t contain forbs and other non-grassy indigenous species. The selective herbicides used in seed production can be used to control many types of weeds growing with native grasses. This can be used to prepare a remnant site before biodiversity enhancement (planting forbs etc), or harvesting to dramatically reduce the amount of weed seed collected.

Careful spot spraying can kill weeds like these Serrated Tussock plants without killing native plants, even when they are this close together.

This paddock of remnant Danthonia was first spot sprayed to control Serrated Tussock, and then boom sprayed to control annual grass weeds. The seed harvested from this site is clean enough for us to use in our seed production area. This photo shows a comparison of treated versus untreated to demonstrate the effectiveness of some of the available methods of selective weed control.

This is the treated site two months later.

Selective control of Romulea rosea in a Stipa and Themeda dominated grassland.

Selective control of Pennisetum clandestinum (Kikuyu) with Themeda triandra.