AS GROWERS prepare for the season, they are being warned to consider future rotations when applying herbicide.
Weed specialist Mark Congreve, Independent Consultants Australia Network, says it is important to understand the soil persistence of a herbicide and its potential impact on following crops in the rotation, prior to the herbicide's use.
"Herbicides designed for residual weed control need to provide weeks or months of persistence in the soil to achieve their desired weed control objectives," he said.
"As well, some herbicides that typically are used for post-emergent weed control and which are not typically considered 'residual' herbicides may also persist in the soil for some time after application."
GRDC has released a national reference manual, Rotational Crop Constraints For Herbicides Used In Australian Farming Systems, to provide graingrowers and advisers with relevant information to assist them to plan herbicide use in crop sequences and rotation constraints.
The manual is divided into two parts with the first covering the principles of herbicide persistence in the soil and the factors that influence herbicide breakdown.
"Understanding these factors may help to predict variability from year to year under different environmental conditions, to assist decision making in situations where labelled plant-back requirements have only just been met, or where statements on the herbicide label do not adequately cover the paddock situation," Mr Congreve said.
Part two is a summary of label statements relating to directions for managing rotational crops.
The manual contains a series of frequently asked questions and links to other useful resources.
