FARMERS should be vigilant about controlling weeds before seeding to ensure future yields are not compromised, according to local agronomists.
Carr’s Seeds agronomist Denis Pedler, Port Lincoln, said croppers in his region were out spraying summer weeds, in particular fleabane, marshmallow, Lincoln weed, melons, volunteer cereals and volunteer canola, with some on their second pass.
Mr Pedler said croppers looking to spray herbicides should watch the Delta T closely for effective herbicide spraying, while many should be considering baiting snails soon.
Mr Pedler was concerned the green bridge would carry disease and pests, such as Russian wheat aphid or bluegreen aphid, into the following season.
YP Ag agronomist Chris Davey, Kadina, said farmers in his region had been spraying summer weeds since early January, with some also on their second pass in parts.
“Some weeds that have been growing since October, are larger than farmers would prefer for summer spraying,” he said.
Flaxleaf fleabane, potato weed, wireweed and milk thistles were the most problematic weeds, with milk thistle of particular concern due to its developing resistance to glyphosate, while wireweed and fleabane were also tolerant of chemicals.
“We need higher rates of chemicals to control them,” he said.
Mr Davey recommended farmers look for troublesome grasses, including windmill grass and feather top Rhodes grass, that survive the summer weed spraying application.
A double knock should be used to improve control of flaxleaf fleabane, he said.
Mr Davey did not have concerns about weed spraying having an effect on seeding.
“Summer weed spray conserves the moisture and nutrients in the ground as it does not give the weed an opportunity to use them,” he said.
“But farmers should still be aware of plantback periods of the chemicals that they are using going into the appropriate crop, and abide by these time frames after the required amount of rain has been received.”
