A plant out of place
Deciding if a plant is feed or weed
.JUST goes to show you the distribution of the popular
Rural Weekly paper goes far and wide and the readership also is far and wide.
I had a phone call last week from the northern regions of Queensland, taking me to task about calling button grass a weed and advocating control measures around this particular plant’s ecology facets. That is looking at button grass’s achilles heel and using the best tactics of our multi-pronged Big 6 of Weedsmart control ploys, as we do these days of increasing herbicide resistance.
Of course, my answer is by definition that a weed is a plant out of place and that was my first defence in the long and humorous phone call from Charters Towers.
Fortunately, I knew exactly what my caller was on about as my father-in-law in the early 1980s in the north, had me scouting for urochloa seedlings in his cattle blocks, that he had planted in the wet season and was hoping the roos had not eaten them all.
I thought this was fairly ridiculous at the time in actively looking for urochloa plants in my holiday time, whereas, in my southern Queensland work, efforts as a young agro, I was trying to control this prolific grass weed in farming areas.
Of course, the true definition of a weed is a plant out of place and we all agree that having volunteers from a previous crop is just like having a paddock of weeds.
There are plenty of examples however one that springs to mind is grain sorghum volunteers in a mungbean crop. Apart from moisture and nutrient usage, the grain sorghum seed going into the mungbean sample has to be graded out and that takes time and money to bring the mungbean sample up to spec. Not a good combination.
Back to my northern caller: After about 30 minutes of genial chat, he saw my point of view about my definition of a weed, which is what I called button grass in the article. I was however reminded the definition of a weed may be dependant on the environment and location in which they grow. Look at annual ryegrass in the southern and western states where years of planting for livestock feed value has now given us one of the world’s most herbicide-resistant plants on the earth.
The photo, above, is of a local south Queensland grain sorghum crop with Johnson grass growing in it. Johnson grass can feed a lot of livestock in tough times and we all know how big a root system this tall perennial grass plant can develop.
Still, in a sorghum crop we do not like it growing and our export markets like it even less.
One plant I cannot find a place for is parthenium weed. Not that we know it has any herbicide resistance levels however I cannot find a place for it in my useful plant book for any environment.
No doubt some Rural Weekly reader will tell me differently.
Another weed I spent much of my youth controlling was Noogoora burr. Next thing I hear from Dad, is Noogoora burr is being researched for medicinal purposes and we could be actually growing it for a commercial use.
As a young bloke with a wellused chipping hoe, I was fairly happy about this development possibly halving my workload. Then the wheels fell off the Noogoora bandwagon because, in dense populations it developed a specific rust badly, which I could have told them early in the piece. Back to the chip hoe...
Weeds, or plants out of place, can occur in different locations and do adapt to changing environments. So I hope the button and the urochloa grasses grow extremely well in northern livestock regions however, if those folk ever want to grow a commercial crop of grain sorghum or mungbeans, those two weedy grass plants are going to be a problem with the seed bank they may have left in the soil.