Rice safety and control of penoxsulam-resistant and -susceptible barnyardgrass (Echinochloa crus-galli) populations with soil-applied herbicides

Abstract

Resistance to penoxsulam among barnyardgrass populations is prevalent in rice fields in China. Seeds of penoxsulam-resistant (AXXZ-2) and -susceptible (JLGY-3) barnyardgrass populations, as well as the seeds of two rice varieties including Wuyungeng32 (WY) and Liangyou669 (LY) were planted in plastic pots and then treated with a rate titration of acetochlor, anilofos, butachlor, clomazone, oxadiazon, pendimethalin, pretilachlor, pyraclonil, or thiobencarb. The two barnyardgrass populations exhibited similar susceptibility to acetochlor, anilofos, butachlor, oxadiazon, pretilachlor, or pyraclonil. However, the susceptibility differed between the barnyardgrass populations in response to clomazone, pendimethalin, and thiobencarb. For AXXZ-2, herbicide rates that caused 50% reduction in shoot biomass from the nontreated control (GR50) were 179, >800, and 1798 g ha-1 for clomazone, pendimethalin, and thiobencarb, respectively; while JLGY-3 GR50 values were 61, 166, and 552 g ha-1, respectively. Both rice varieties demonstrated excellent tolerance to acetochlor, butachlor, oxadiazon, pretilachlor, and thiobencarb. However, substantial rice damage was observed with anilofos and clomazone. Anilofos at 352 g ha-1 and clomazone at 448 g ha-1 reduced rice shoot biomass by 41 and 50% from the nontreated, respectively. Averaged across herbicide rates, clomazone reduced rice shoot biomass from the nontreated control by 52 and 34% for WY and LY, respectively; and pendimethalin reduced rice shoot biomass from the nontreated control by 25 and 9% for WY and LY, respectively.

Weed control and water‐seeded rice response to pyraclonil applied at different timings and in herbicide combinations

“…It is a broad‐spectrum pre‐emergent herbicide largely used in Asian rice production systems with activity on broadleaves and grasses (Wang et al., 2021; Zhang, 2014). In Asia, pyraclonil is used to control herbicide‐resistant weed biotypes and is useful when incorporated in season‐long weed management programs (Hamamura, 2018; Liu et al., 2021). The US Environmental Protection Agency has recently approved the registration of pyraclonil (Zembu™, Nichino America Inc.) in the US for early‐season weed control in water‐seeded rice (US EPA, 2023).…”

Post-Emergence Water-Dispersal Application Provides Equal Herbicidal Activity against Echinochloa crus-galli and Rice Safety as Foliar Spraying of Penoxsulam

“…As a result, an extended period of time is needed for the creation of shade by the standing rice seedlings, causing the prolonged requirement of weed control [11]. E. crus-galli is one of the most prevalent and troublesome weed species in rice production in China, which can cause as much as an 80% rice yield reduction if uncontrolled [18,19]. Since E. crus-galli has morphologic similarities to rice, and along with its extended emergence throughout the growing season, high photosynthetic capacity, and prolific seed production, this makes it highly competitive and hard to control in paddy fields [20].…”