By Amelia Genis
The increasing use of herbicides in conservation farming systems in Australia, as well as the development of weed resistance to herbicides, is concerning, says Prof. Ken Flower, director of the Australian Herbicide Resistance Initiative (AHRI) in Perth.
The technology to detect weeds in a field and control them selectively already exists. However, not all farmers keep records of where the weeds have been controlled.
“I believe if we can map weeds and predict where patches will appear next year, it can help farmers apply integrated weed management strategies instead of spraying herbicide over the entire field.
Flower said at the ninth World Congress on Conservation Agriculture in Cape Town that farmers already regularly collect spatial data on biomass, yields, soil structure, and slopes.
“If we can detect and map weed patches in fields, we can apply weed control just where the weeds occur. What if we could also predict where weed patches will appear next year?” said Flower.
Scientists from AHRI are working on a new project to predict the location of weed patches so that they can be controlled in the future. Instead of applying herbicide over an entire field, a farmer can do a variable application of herbicides or increase seeding density at those spots to increase the competitiveness of grain plants.
They are already using a simple model that utilises satellite data to see what is happening on the ground to improve it.
Weeds adapt
According to Flower researchers recently been found that weed species adapt in various ways to thwart control.
Greater dormancy in weed seeds and delayed germination, presumably in response to pre-emergence herbicides, have been found in certain weed species, while others bloom earlier and seed in response to herbicides.
Farmers often perform weed control during harvest time (with weed seed destructors) or just afterwards by baling windrows. This way, they could get rid of wild radish that shed their seeds at harvest time. Researchers have found wild radish plants that shed their seeds before harvest to escape the harvest weed seed control methods.1
