Fixing your oats weed problems
SOME weeks ago I mentioned this year may be a bad season for winter weeds and unfortunately I have been proven correct in early paddock inspections.
The group of weeds I would like to highlight is one of the main grass weeds we get in our winter cereal crops including the competitive black oats and phalaris as two of the major contenders.
When I say competitive I mean competitive, as 50% yield reductions can easily be obtained by letting wild oats go ballistic.
The list of post-emergent control agents for these grass weeds is quite large and to a certain degree confusing with active ingredient names like clodinafop, flamprop methyl, pinoxaden, fenoxaprop and tralkoxydim to name a few options.
So let's start at the beginning with controlling our winter grass weeds.
Avadex, with the active ingredient trialate, is an old fashioned herbicide that needs incorporation into the soil before planting a wheat, barley or chickpea crop.
It is a well acknowledged fact that when the black oats population is heavy, this group E shoot adsorbed herbicide will give you the best yield due to early control of your extensive black oat population.
It may not finish up as the cleanest paddock due to Avadex's length of activity of only six to eight weeks, however the maximisation of the yield is achieved.
For many of us this option has long since passed and even the planting window is closing up for many of our number to employ the next part of the action plan.
So the choice of row and plant spacing is highly important in general weed control and even more so with black oats and canary.
In other words, the simple action of crop competition will do much to reduce in particular your black oat issues.
So employing a 20 inch row spacing with wheat or barley is not the best consideration, if trying to control a rampart population of black oats.
At this time I suspect many of us have crop in the ground and are finding what our last two growing years have delivered to our seed bank population of grass weeds.
It is well accepted that our dormancy of black oats is around six months, however they can last for three to five years to provide a source of a starting population.
Bear in mind that one well grown black oat plant growing with your winter cereal crop can drop 200 odd seeds on the ground for the next year.
Now the bad news is that Queensland black oats are fairly difficult to control in respect to other southern types, which is why products like the diclofop methyl (Hoegrass) or difenzoquat (Avenge 650) were not that effective, when they were the pick of the safer products in use in the late '70s and early '80s.
Along came flamprop methyl - Mataven as it was called in the early '80s.
This group K herbicide has been effective on black oats in wheat and really still gives us an option to go to, if widespread resistance is suspected to the group A's of Wildcat, Achieve or Topik type products.
The fortunate case for us all has been the major price decreases that have occurred in our post emergent grass herbicides.
Many of these older generic products start at $3 per acre cost these days for small black oat control in wheat, which is a huge decrease in price from the early days where black oat control started at $12 per acre plus oil.
This allows us the luxury of using rates that are extremely effective in the paddock.
So black oats I believe, are going to be prevalent this year, so make sure of your identification skills with respect to leaf curl direction, auricles present, mid row presence or small leaf edge hairs and if all else fails, dig up the tell tale seed.
Spraying these potential admix partners should still be done early in the piece.
Be aware, that while we can tank mix some broadleaf herbicides with our grass products, you do lose some activity on the black oats by choosing to do a single pass control over the paddock.
As is the case with many of our herbicides, you need active growth in the weed to facilitate a successful job.
You also need active crop growth to give us a decent level of crop safety when choosing to use these chemicals.
Next week, more about wild canary (phalaris) which is also very prevalent around many areas.
FROM THE PADDOCK
By PAUL MCINTOSH
Landmark Toowoomba
