Wednesday, May 22, 2024

New Weed in California Rice: White Water Fire

⋅ BY WHITNEY BRIM-DEFOREST ⋅
University of California Cooperative Extension

White water fire (Bergia capensis)

White water fire (Bergia capensis) was found in September 2023, by the Butte County Agricultural Commissioner’s office in a Butte County rice field. The weed was identified by the California Department of Food and Agriculture. It is the first find of this weed in California, and possibly in the United States. It is native to Africa, southern China, and tropical Asia. It is known to be in rice fields in Europe, Central and South America, as well as the Caribbean.

This weed was found in one rice field, and the Agricultural Commissioner’s office surveyed surrounding fields but found no additional infestations. The introduction method in California is currently unknown.

It has a “Q” rating by CDFA: “An organism or disorder suspected to be of economic or environmental detriment, but whose status is uncertain because of incomplete identification or inadequate information”. At this point, it is not considered a quarantinable pest, so if it is found, there is no penalty or restriction for finding it in a field.

Identification

Redstem (Ammania coccinea)

White water fire looks similar to another common rice field weed, redstem (Ammania spp). However, the two species are not from the same plant family and are not closely related. Due to the similarity, white water fire is difficult to identify in the field. One key distinction is the thickness of the leaves, which are much broader in white water fire than in redstem. Another key distinction is flower color. The flower color of white water fire is white, whereas redstem can have either purple or red flowers.

Possible control

UCCE will be scouting and collecting seeds in the previously infested field again in 2024. In other countries, pretilachlor has been used, as has metsulfuron. However, neither of these products are registered in California rice, although some herbicides in the same mode of action are registered and may be effective. Extensive testing with registered herbicides and herbicides in the registration pipeline will need to occur before recommendations are made.

Currently, the best recommendation for control is to hand-rogue (pull) out the plants. Other recommendations are to thoroughly clean equipment between fields when moving from an infested field to a non-infested field.

Reporting 

If you suspect you have this plant in your field, please give your nearest Rice Farm Advisor a call. They can assist with identification, as well as control strategies.

Related Articles

Connect With Rice Farming

Quick Links

E-News Sign Up