Herbicide caution for alkaline soils

Photo of a farmer holding clumps of alkaline soil

Sulfonylurea herbicides will easily leach and persist for long periods in alkaline soils, a new CRC for Soil and Land Management project has found.

This project is investigating the behaviour of Group B herbicides (including sulfonylurea) and has already issued some useful hints for good stewardship on these soils:

  • read the label — be precise about maximum rates and minimum plantback periods
  • know your soil pH: sulfonylurea herbicides may leach quickly into subsoil
  • select the best weed control methods: herbicide resistance is a problem with Group B herbicides.

Is there an alternative method of control — a different type of herbicide or another weed control technique?

  • crop choice: consider sensitivity of crops to sulfonylurea when designing your rotations and deciding on plantbacks
  • watch your plantback periods: chlorosulfuron and triasulfuron labels carry qualifications for plantback periods related to sensitive crops. Extend plantback periods in paddocks with a history of soil-borne diseases or trace element deficiencies.

Contact: Mr Nigel Wilhelm 08 8303 9353