Do’s and Don’ts when using Group A herbicides in rice
Good weed management always begins with a foundation treatment. When a secondary control of grass weeds is required, we are relying on a Group A mode of action. Group A’s are high risk for resistance management according to Croplife Australia.
Be aware of off-target spray drift damage on sensitive crops when using herbicides in summer fallows. Take care to avoid spraying when hot temperatures are predicted and where surface temperature inversion conditions exist.
Integrated weed management is the coordinated use of a range of suitable chemical and non-chemical control methods. e aim is to incorporate a variety of control methods and reduce reliance on herbicides. Successful integrated weed management programs require long-term planning, knowledge of the weed’s biology and ecology as well as appropriate weed control methods.
Knowledge of a product’s translocation and formulation type is important for selecting nozzles and application volumes.
Evenness of deposit is important for poorly or slowly translocated products.
Crop growth stage, canopy size and stubble load should in uence decisions about nozzle selection, application volume and sprayer operating parameters.
Robust rates of products and appropriate water rates are often more important for achieving control than the nozzle type, but, correct nozzle type can widen the spray window, improve deposition and reduce drift risk.
Travel speed and boom height can affect control and drift potential.
Appropriate conditions for spraying are always important.
Clomazone (Magister®, Director®) is a very effective herbicide for the control of barnyard grass. Many growers however have avoided using it because of concerns with its potential to damage rice. Rather than excluding clomazone from the list of chemicals considered for grass control, it would be better to know how to safely use it and retain it as a viable and beneficial option.
Herbicide resistance management is critical to retaining these valuable tools for rice growing. Resistance is rendering weed control increasingly difficult and more expensive in most significant rice producing countries; including the USA, Vietnam, Thailand and Japan.