Ian Chivers, Native Seeds
In the first article of this short series I talked about the growth patterns of the cool
season grasses and how they varied from those of the warm season grasses. I
suggested that we can use the different growth habits to provide strong competition
to African Lovegrass (ALG) when it is at its’ weakest at the early seedling stage in
Spring. Using a strong growing cool season grass cover to compete with a warm
season seedling is a very useful tactic that has been shown to work on other weeds
and can be utilised to great effect on ALG.
What Cool Season Grasses?
So what cool season grasses are best to use? The ones with which we are most
familiar are the introduced favourites – ryegrass, phalaris and cocksfoot. We have
grown them for decades and we all know their limitations – for the most part that
comes down to lack of persistence for ryegrass; very slow establishment, potential
death for grazing animals through staggers and intolerance of acidic soils for
phalaris; and slow establishment along with higher fertility needs of cocksfoot.
So what about some of the native grass options? Generally speaking the native
grasses, owing to their long-term adaptation to Australian soils and climate are well
suited to growth here. But which ones? The three that I will focus on for this article
are Wheat grass (Elymus scaber), Wallaby grass (Rytidosperma spp.) and
Weeping grass (Microlaena stipoides).
Wheat grass is a vigorous cool season grass of high pasture quality and,
surprisingly, high vigour. Many native grasses are noted for their slow establishment
and relatively low biomass production, but wheat grass is an exception. Our native
wheat grass (Elymus scaber), sometimes called common wheat grass, is a
widespread cool season native grass that can produce similar volumes of foliage to
perennial ryegrass and indeed looks quite similar to that grass. It is highly persistent
through drought and would be more widespread except that it is quite highly
palatable to stock and is readily eaten out. This is usually sown in autumn or early
What is intriguing to me about this grass is the green material it produces over the
summer. Our seed production stands remain green throughout the summer, even
after the seed has been removed. Any summer rainfall promotes rapid growth. Just
as a caution, a really harsh summer will deplete this grass, if it is set stocked or heavily grazed. Incidentally it is now recognised as being one of the most valuable
fodder grasses for horses owing to its significant bulk of dry matter combined with
high starch and low sugar content.
Just to make sure here I want to spell out that this is not Tall Wheat grass, which is
an introduced grass that was recommended for saline areas. It too is now becoming
a weed concern across much of southern Australia. And just to be complete I also
need to make the distinction around the drink made from munched up seedlings of
wheat – that also is not the wheatgrass about which I am talking.
Wallaby grass really refers to a whole family of grasses, not just one species. Indeed
there are roughly 30 to 40 species that are commonly called ‘wallaby grass’ or ‘white
top’. The taxonomists will tell them apart by the nature of the hairs on the back of the
seed and the awn, but for most of us the biggest differences are in their mature size.
There are large leafy types that can be as tall as 1.3 metres and small types that
reach no higher than 0.1 metres high. They are generally described as highly
persistent species, very drought adapted and suited to poor soils, but as you can
imagine with such a wide range of species growing naturally across southern
Australia there are types that grow almost everywhere – from saline soils, to stony
ridges, to waterlogged soils and even to lawns.
In animal nutrition terms they are comparable to many of the introduced grasses
when at their peak, and I think here specifically of types such as Bunderra that have
been selected by the NSW Department of Agriculture for pasture use.
Then there are other types such as Hume which was developed by the CSIRO in
Canberra specifically for roadside and other low-maintenance uses where
persistence is the most desirable characteristic rather than dry matter. Another
variety that we have developed is Oxley which is small in stature and has been used
extensively in between rows of vines or in lawns where persistence and low biomass
production are specifically desired.
Weeping grass (Microlaena stipoides) is another very useful grass type that has a
huge potential for use in pastures around the southern tablelands. It is very well
adapted to acidic soils, drought, grazing and shade. It is often the first grass to come
back once a drought breaks and provides high quality fodder, especially for cattle. It
is naturally occurring across all of the higher rainfall and cooler zones of southern
Australia and has a huge natural diversity. Weeping grass is able to produce a lot of
highly palatable foliage with relatively few inputs.
Some varieties have been developed for particular purposes such as Ovens and
Wakefield for pasture, Griffin for turf and amenity and Shannon and Bremmer for
revegetation. These varieties give landholders the ability to choose a particular
variety especially for their desired use.
While the establishment of weeping grass is slower than some other species, it is
very strong once established and will persist for decades once sown. It is also able
to recruit well for the following generations and will spread readily if conditions suit it.
Once again there is a large range of spear grass types, the Austrostipa family, many
of which occur naturally across the southern tablelands of NSW. They are less
palatable than the other grasses I have been talking about and have the major
detraction of a very sharp and intrusive seed (hence the name). While these are
amongst the hardiest of the cool season native grasses to be found in the area with
many persistence benefits, the difficulties caused by the seed limit where these
grasses can be used. The most common applications for deliberate sowing are in
non-grazed areas such as roadsides, steep cuttings and so forth.
Seedlings of spear grass are relatively slow to establish and remain small for a
lengthy period. If they are not trampled or smothered they will grow out to be
substantial plants after about 18 months.
It is by using these grasses cleverly as competitors against the new seedlings of
ALG, that some strong competition can be established which can help to prevent the
invasion of that weed. The strategic use of native grasses offers the potential to gain
a valuable pasture that needs few inputs and which can be highly competitive
against encroachment by ALG.
In the next article I will talk about the methods of establishing these native grasses.