There is no doubt that this springtime of year certainly shows how good our winter crops are going to be.
It also shows up some very pesky, predominantly winter weeds, as they near seed set and maturity.
Several nasty scenes have greeted me in my travels around South Queensland these last couple of weeks, and one of them is in the attached photo.
It looks innocuous enough; however, this is Australia’s number one cropping weed that also happens to have multiple resistance levels or folds to our key knockdown and in-crop herbicides.
Annual Ryegrass, or Lolium rigidum to be technically correct, is an excellent livestock fodder, as it has been since the early 20th century across much of Southern and Western Australia.
Unfortunately, over the following decades of livestock number reductions and increased grain production under improved mechanisation, desirable fodder plants like Annual Ryegrass (or ARG) have really excelled at becoming herbicide-resistant weeds to various herbicide modes of action we use in our annual cropping phases.
This one little shiny-leafed plant, with the ability to germinate from 5°C to 35°C, really does open the Queensland door for the establishment of yet another plant out of place, or weed.
With the ability to produce a couple of thousand seeds on a robust Annual Ryegrass plant, plus multiple resistance to a range of herbicides like glyphosate, sulfonylureas, trifluralin, triazines, triazoles, and our extended range of FOPs and DIMs in Group 1, we really have created a super plant.
I first heard reports and then observed ARG around several Southeast Queensland feedlot areas.
Then I witnessed first-hand how these truckloads of hay, brought in during the drought-ravaged years of 2017 to 2019, included weed seeds from the south.
These much-needed loads of hay were unintentionally bringing and depositing Annual Ryegrass seeds into table drains, farming paddocks, and around plenty of guideposts and local roadside furniture.
Thankfully, it can be managed in our summer and winter cropping sequences.
However, this annual grass plant can pop up in the most inopportune farming systems, where we cannot control it by herbicide use alone or just by applying mechanical tactics.
My best thought is to stop any weed seed set.
It seems like a simple enough process, and as an agronomy friend said to me many years ago.
“If you can stop an annual plant from going to seed, you will never have herbicide resistance and you won’t have too many weeds either.”
Pretty true, however, never as simple as that.
So our herbicide strategy needs to be precise and include a range of other practices or tactics, like harvest weed seed control as one of them.
Your fence lines, creek banks, contour banks, power line posts, and even areas around your own or your neighbours’ grain silos can all be considered nurseries for this pesky weed.
Keep a close eye out for this plant we call a weed, and make sure you get good control on Annual Ryegrass (ARG) before it sets seed.
