New Herbicide Registered in California Rice for 2024: Cliffhanger™

California rice growers will have a new herbicide available this year: Cliffhanger™, manufactured by Gowan Company. The active ingredient is benzobicyclon, which is the same as one of the two active ingredients in the currently registered herbicide, Butte®. Cliffhanger™ is a soluble liquid formulation (SC) which can be applied by ground-rig or airplane, including as a direct-stream application into the water. In contrast, Butte® is a granular formulation, as a pre-formulated mixture of benzobicyclon and halosulfuron. To use either product, applicators must attend a training and be certified.

Dates for the training are posted on the California Rice Commission calendar https://calricenews.org/events/, as well as the UC Rice website.

Controlled weeds are sprangletop, ricefield bulrush, and smallflower umbrella sedge. The application timing begins from day of seeding up to 82 days before harvest. Recommended timing for sedges is pre-emergent up to the 5-leaf stage, and for sprangletop, pre-emergent up to the 2.5 leaf stage as well as at tillering.

Flood water should be a minimum of 4 inches when the product is applied. The active ingredient, benzobicyclon, is a proherbicide, meaning that it is not active until it comes into contact with water. Therefore, for maximum efficacy, water should be held in the field for at least 5 days. Longer periods of flooding will result in better efficacy, whereas a drain soon after application will both reduce efficacy as well as encourage a new flush of weeds. The recommended waterhold is 10-14 days for maximum efficacy.

Cliffhanger™ should only be applied once per season. It is not recommended that it be applied in the same season as any other HPPD-inhibitor product (Butte®). Applying both in the same season can select for herbicide resistance and may cause significant phytotoxicity to the rice. Repeated applications, both during the same season, or season after season, can select for resistance, particularly in sprangletop, ricefield bulrush, and smallflower umbrella sedge.

Remember to always follow all label instructions when applying any pesticide, as the label is the law. Make sure to pay particular attention to the Use Precautions and Restrictions. Consult your local Agricultural Commissioner's Office regarding buffer zones and aerial restrictions, before making any applications.

Label and SDS: https://www.gowanco.com/products/cliffhanger-sc-herbicide

 

Original source: Rice Notes - January 2024 newsletter