When applied in winter cereals, aminopyralid, clopyralid and picloram based herbicides can provide knockdown of a range of broadleaf weeds. Additionally, these winter applications may also provide useful residual control of spring germinations of weeds such as fleabane.

Where these herbicides are used in winter cereals, care must be taken to avoid herbicide carryover in the following season, especially where a pulse crop is to follow the winter cereal.

Key Points

• Some Group I pyridine herbicides can have extended residual persistence under certain conditions.
• When used in winter cereals, aminopyralid, clopyralid or picloram based herbicides may provide residual control of certain broadleaf weeds in the following spring.
• Under certain conditions, persistence may affect pulse crops or legume pastures grown the following year.
• Applying early post-emergent in the winter cereal crop usually optimises knockdown and residual control, while reducing carryover concerns.
• Where these herbicides have been used in winter cereals, the safest option is to plant a cereal crop or canola in the following season. If considering sowing a pulse crop in the following year, remove or incorporate cereal stubble immediately after harvest, ensure there is adequate summer rainfall for herbicide degradation and read and follow all label directions, especially with respect to follow-crop intervals.

Further information

Wells, G. (2019). Safe use of Lontrel® Advanced in Southeast Australian crop rotations. GRDC https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2019/02/safe-use-of-lontrel-advanced-in-southeast-australian-crop-rotations

Dow AgroSciences (2014). Lontrel® Advanced. Potential herbicide carry-over issues. http://msdssearch.dow.com/PublishedLiteratureDAS/dh_08fc/0901b803808fcc40.pdf?filepath=au/pdf