We are getting huge enquiry on Chilean Needle Grass (CNG) over the past few weeks, and with good reason, as it has exploded around the district this year. The good season has seen CNG proliferate and pop up in areas where it has previously never been seen.

When we look at control strategies for weeds, we tend to focus on their weaknesses and then take advantage of those weaknesses. We then use any methods at our disposal to exploit that weakness.

So how do we get rid of problematic weeds?

Chemical control

Farm Hygiene and Biosecurity

Exclusion

Mechanical means (Slashing, Cultivation, Kelly chains etc)

Pulling

Strategic Grazing

Burning

Competition

We tend to get fixated on chemical control options as they tend to be the  easiest and often cheapest way to get in top of problematic weeds. However, we cannot forgot other cultural methods as they can also help manage stands. Herbicides are a necessary evil in many cases, but do provide significant advantages in winning battles earlier. Use them as per the label and they will be one of the greatest tools you have in the armoury on this plant.

Back to CNG and this is where things get interesting but also very frustrating. CNG whilst not bulletproof, is one very tough hombre with a formidable arsenal and very few weaknesses.

We have a plant that for a start that is a real survivor. CNG May only produce 20,000 seeds per square metre (believe it or not, that is relatively light for an invasive grass), but 98% of them survive! Compare that with its close relative Serrated Tussock which produces up to 150,000 seeds/m2, but only a survival of 10-15% and you see it really is a numbers game.

This gives an insight in to why CNG is so aggressive, one seed equals one plant!

Then we take into account how CNG spreads. It is a heavy seed meaning it is not windborne (unlike serrated tussock), so drops relatively closely to the mother plant. This gives us a slow lateral spread, but the genius part is the hooks on the end of the seed. CNG seed sticks beautifully to anything that has wool or fur, meaning simple wildlife such as Kangaroos become a vehicle for dispersion as well as your livestock. Sheep are particularly at fault for spreading this grass.

It is also extremely difficult to remove from machinery such as farm vehicles, contractors vehicles and farm visitors. This includes powerline contractors who drive through your property to access their infrastructure. And yes it most definitely includes your local Agronomist.

Now we have established that CNG is a relatively modest seeder, but easily dispersed and is a survivor. How do other control methods fair in our armoury against this plant?

Slashing - Can be a way of removing the seed head which is the nasty part of this plant, but like all other weeds, it will require multiple applications. Not all seed heads mature at the same rate, so you have a staggered seeding time making it difficult to slash effectively.

Add to this complexity that you can spread seed readily on the slasher itself and you can be making the problem worse. To make it really taxing, CNG not only produces aerial seeds, it produces seeds within the stem that are spread readily from mechanical means.

Cultivation - CNG has this one covered as it not only produces Aerial seed heads and stem seeds, it also produces Basal seeds under the crown. Yes you heard that right, this plant produces seed in 3 places. Now when you cultivate you spread but also stimulate the basal seeds to germinate.

Pulling- this includes physical removal of the plant and incineration of the seed heads. This is at best achievable on small acre areas or isolated plants. Much of the district is already beyond this scale.

Exclusion - This can be either fencing these areas off and fighting the spread from the fringes, and most definitely includes keeping livestock out of these areas at certain times. A very smart way is to exclude all sheep from affected areas from Flowering (November-December) to seed drop (January-February). This not only stops further spread but prevents damage to the carcass as the seeds penetrate the skin.

This also applies to vehicles and farm machinery.

Strategic Grazing - Graze infected areas hard when there is no seed head present and remove them when seed head emerges. This takes some managing especially in dry times.

Burning - like all good weeds burning can actually stimulate further germinations, and in the case of CNG this definitely applies. You get rid of the mature plants and cause a huge germination of seedlings, making the situation infinitely worse on the long run.

As our list is running out, we are left with Farm Hygiene/Biosecurity and Competiton. This is where agronomists are fighting the war on this weed.

Farm Hygiene/Biosecurity - Making sure that all visitors on your farm are coming and going clean and haven’t been on CNG infested pastures. Think of all the vehicles that drove across your property every year and this is a big job. Educate people of what the plant looks like so they can avoid it, or have those areas fenced off to avoid access.

Give livestock an area to empty out in upon entering the farm, especially if they have come from areas known to have CNG.

Avoid using contractors that work in CNG infested areas whilst the plant is flowering and seeding. Use them in times where the plant is not problematic, such as Autumn and Winter.

Competition - This is where we must win the war one battle at a time. I have said many times that competition is our greatest herbicide and it is true. Once areas have been overtaken, remove those paddocks with herbicide and plant them down to the most aggressive species, which is aggressive at the right time of year. In the New England this involves Annual Ryegrass. Sow them down, remain productive, reduce the seed set and deplete the seed bank, but be prepared to rinse and repeat often.

So will you eradicate CNG from your farm, employing all of the above methods? The simple answer is NO.

CNG has been in the district for about 30 years and I have seen no single strategy work in eradication. I have seen some very effective management of this weed, whereby it is not fatal to the operation, so this must be the approach and the mentality.

Use all methods mentioned, keep it to where it is, fight like buggery to contain it and try everything to prevent its further spread. This is a war that must be won, for losing it long term will be unthinkable. We have perhaps 10 years to prevent this disaster.

If you need an identification of CNG or need strategies to help fight, don’t hesitate to contact the agronomy team at Grazag in our 3 branches.

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