Recreating the Country blog
Trouble from the Veldt has appeared in my ‘backyard’ in the form of three invasive grasses that are threatening to displace remnant grasslands in three reserves that I help manage. The indigenous plants that have succumbed are extremely tough and hardy, but they are no match for this trio from the Veldt.
The South African Veldt is a wide open plain and its literal translation from Afrikaans is ‘field’, originating from Old Dutch. In South Africa the Veldt can be predominantly grasslands or a combination of grassland with shrubs and open woodlands. This type of landscape will sound very familiar to Australians.
Because of its exposed, dry climate the Veldt has produced plants that are very tough, so not surprisingly the Veldt grasses that were introduced to Australia as pasture grasses and for binding sandy soils, have adapted so well that they have invaded many waterways and nature reserves in Western Australia, South Australia and Victoria.
The three Veldt grasses causing the trouble are Panic Veldt Grass, Ehrharta erecta, Annual Veldt Grass, E. longiflora and Perennial Veldt Grass, E. calycina. Each species of grass is very invasive, fast growing, have done well in the extreme dry of the recent drought years and adapt well to wet years as long as the soil is well drained. They seem pretty bullet proof though some chinks in their armour are beginning to appear
In Central Victoria near Teesdale and Inverleigh which is my backyard, these Veldt grasses have invaded grasslands and grassy woodlands, displacing many of the indigenous grassland plants. Disappointingly they are not considered pest plants by government departments, though the Departments will indirectly fund their control because they are causing a loss of biodiversity values. Disappointingly this troublesome trio are not declared pest species because they are not a pest for the farming community.
Panic Veldt Grass
This is a common garden weed that is easy to manage in a garden environment. A professional gardener I know doesn’t mind it at all because it is very easy to pull out. It will however go from germination to seed production in only 2 – 3 weeks which enables it to spread even with the best gardening practice. It has the ability to grow in shade and under trees where other grasses don’t grow. In my own native garden it will grow unnoticed under bushy Correas and Grevilleas. Thumbing its nose at me as it appears out the top of the shrubs in late spring, having already dropped thousands of seeds for the next germination. Did I forget to mention that it will
germinate in any season?
Aside from hand pulling then mulching to prevent the next round of germination, I've found that spraying with Fusilade Forte at 16ml/10L water (0.8L/ha) works well. This is half the recommended rate but it works on this annual grass. This is a specific herbicide for grasses and it won’t affect woody shrubs or broad leaf plants and is reasonably safe to handle.
Interestingly all of the Veldt grasses are weakened by heavy grazing and regular mowing, so they are usually absent from farm pastures. This is ironic since the Perennial and Annual Veldt grasses were introduced to Australia as pasture grasses.
This is an observation we are planning to exploit in the smallest of the local reserves which is 8ha and fully fenced. Introducing strategic grazing with a large flock of Merino sheep should restore the balance and significantly reduce their dominance. The plan is to heavily graze the veldt grasses this year to weaken their hold. In future years we plan to remove the sheep for the spring flowering cycle of the indigenous grassland plants to enable them to re-establish.
Update on the grazing trial. 20/12/2016. See also photos below
After 30 days of grazing the flock of Merino sheep tended to target the Veldt Grasses and leave the Spear Grass, Wallaby Grass and Kangaroo Grass untouched. After 50 days the sheep still prefer the Veldt Grasses with some trampling of native grasses. A very promising result.
An open area of the reserve on the northern boundary was largely ungrazed after 30 days. It is likely that dogs living in these properties have made the sheep nervous because grass near an adjacent property on the northern boundary without a dog is well grazed.
Annual Veldt Grass (AVG)
This is a broad leaf grass that is one of the first to germinate after the autumn break. A diagnostic feature of this grass is red pigmentation at the ligule where the broad leaf branches from the leafstalk. The early germination of this annual, its ability to grow through the winter months and its adaptability to grow in dry shady locations under native trees, even Drooping She-oaks that mulch the ground with ‘leaf’ litter, enables it to invade quickly, like a green blight. AVG will grow to nearly a meter when it’s flowering.
It produces a dense leafy ground cover that has the potential to fundamentally change the fire risk of native grasslands and grassy woodlands. In the 8 ha reserve where the grazing trial is being held, this grass is growing at the base of Rough-barked Manna Gums, Eucalyptus viminalis ssp cygnetensis, This is a frightening prospect for the 9 residences that surround the reserve if a fire ever starts in the grass, as it will run up the loose hanging bark of the Manna Gums and into the crowns in a matter of seconds. That situation would result in glowing embers blowing for tens of kilometres putting many properties at risk
The Kangaroo Grass and Weeping Grasses, that the Annual Veldt Grass is displacing is much safer in the fire season. They are green throughout most of the summer and produce far less combustible matter. In rural areas these native grasses actually reduce the fire risk and are a community asset if they are kept healthy with a cool burn every 5 – 10 years.
Did I mention burning? Sadly burning doesn’t appear to be part of the answer with the Veldt trio as they will recover after a grass fire and may even invade the open patches (interstitial tussock spaces) created by a burn.
As mentioned above, grazing is a powerful tool for the control of these grasses. Persistent grazing by domestic or native animals can eliminate it as can be seen by its absence on private property and a recent observation of the roadside verge of the Inverleigh Nature Conservation Reserve. Three years ago the Veldt Grasses dominated the roadside and threatened to spread into the whole reserve, however the resident 200 (plus) mob of Eastern Grey Kangaroos have developed a taste for them and now keep the roadside verge neatly clipped. The Veldt Grasses are no longer conspicuous and appear to be on the retreat.
Spraying with Fusilade @ 16ml /10L water or Verdict 520 @ 2-4ml/10L water plus 100 ml spray oil /10 L water before September will also kill AVG while having little or no effect on orchids and herbs or the perennial native grasses that are dormant in early spring. This is a useful tool but is an expensive option at $1,000/day for a crew of two spray contractors. Where this method is used in one of my local reserves, volunteers with back packs do some of the spraying.
Perennial Veldt Grass (PVG)
The most noteworthy feature of this 30 cm tall clumping grass is the grey-green colour of its leaf blades and the pink tinge at the base of the clump. Like the AVG it also has a distinctive red pigment at the ligule. In October when it runs to seed it reaches a height of nearly 1m and the sprays of pink flowering stems above the leafy base are easy to identify, even on the roadside travelling at 100km/hr.
The clumps are usually well spaced to minimise competition for its shallow roots, however like the other Veldt grasses it will displace any native grasses and eventually form a pure monoculture.
Grazing is its Achilles heel, though Eastern Grey Kangaroos seem to prefer native grasses unless they are forced to develop a taste for it. Unlike the kangaroos in the Inverleigh Nature Conservation Reserve, in the 25 ha reserve that I help to manage, the 20 resident roos are spoilt for choice and prefer to leave the veldt grasses predominantly untouched.
Glyphosate (Roundup) sprayed at the perennial rate of 1% is very effective but not selective, so spraying tends to bare out the ground around the dead PVG. This is quickly reinvaded by new PVG plants that can germinate at any time, though mostly in spring. Herbicides Fusilade Forte @ 32ml/10L water or Verdict 520 @ 4ml/10L water plus 100 ml spray oil /10 L water are also effective as well as selective.
These invasive grasses are a quiet threat to the survival of our indigenous grasses and forbs in all the southern states of Australia and unlike woody weeds there are no selective herbicides that can be used to control them. Some management can be achieved with herbicides by understanding the growth cycle of these plants and using herbicides that are selective for grasses, so that the herbaceous plants and woody plants are safe. Applying herbicides is an expensive option and only a stop gap measure until grazing pressure can be used to weaken them and potentially eliminate them from our waterways and natural reserves.
Stephen Murphy is qualified in Geology and Environmental Management and has been a nurseryman and a designer of natural landscapes for over 30 years. He loves the bush, supports Landcare and is a volunteer helping to conserve local reserves.