Annual monitoring reveals spatiotemporal dynamics of multiple herbicide resistance in
Echinochloa crus‐galli
populations across Zhejiang Province, C
Yi Xiao, Xiaoming Yao, Honghao Mao, Yong Xu, Ziyue Liu, Yongfeng Li, Xia Yang, Xiangying Liu Abstract
BACKGROUND
Echinochloa crus‐galli is a damaging weed in global rice production with rapidly evolving herbicide resistance. This study investigated resistance dynamics to six major herbicides across Zhejiang Province, China (2022–2024), to inform region‐specific management.
RESULTS
A 3‐year systematic monitoring covering 356 populations from 27 counties revealed that the annual resistance frequency of quinclorac consistently exceeded 50.00%. Cyhalofop‐butyl resistance ranged from 32.18% to 61.18%. Penoxsulam resistance ranged from 24.14% to 50.59%. Resistance to bispyribac‐sodium was detected in 25.00% of populations in 2023 and 81.18% in 2024. Resistance to the newly introduced florpyrauxifen‐benzyl was detected in 49.41% of populations in its first monitoring year (2024). Metamifop remains largely effective due to low resistance frequency (6.90%–16.47%). In 2023, four populations resistant to all tested herbicides were detected, increasing to seven in 2024. Molecular analysis identified acetyl‐CoA carboxylase (ACCase) target‐site mutations I2041N and C2088R and the acetolactate synthase (ALS) mutation W574L as contributing factors, but the majority of cross‐resistant populations lacked known target‐site mutations, suggesting that non‐target‐site metabolic resistance is predominant. Under controlled conditions, propanil maintained complete control against all tested multiple‐resistant populations.
CONCLUSION
Observed trends in E. crus‐galli resistance include the widespread emergence of multiple resistance to ALS and ACCase inhibitors and regional variation linked to cropping intensity. Reported resistance frequencies are conditional estimates from problem fields, not unbiased provincial rates. Non‐target‐site resistance predominates among cross‐resistant populations. Propanil is a promising alternative pending field validation. These findings support developing region‐specific resistance management strategies for rice production in Zhejiang. © 2026 Society of Chemical Industry.