Jk. Norsworthy et al., Agrichemical interactions with propanil on propanil-resistant barnyardgrass (Echinochloa crus-galli), WEED TECH, 13(2), 1999, pp. 296-302
Agrichemical interactions between propanil; the herbicides HOE 30374, pendi
methalin, piperophos, quinclorac, and thiobencarb; and the insecticide carb
aryl were evaluated under field conditions to find synergistic or additive
interactions useful to control a barnyardgrass biotype resistant to propani
l (R-BYG) without injuring rice. Propanil and each compound were evaluated
at four rates for a total of 16 rate combinations for each additive. Averag
ed over all experiments, 2- to 3-leaf R-BYG control with propanil alone at
0.83, 1.65, 3.3, and 6.6 kg ai/ha was 33, 53, 62, and 81% at 7 d after trea
tment (DAT). Propanil-susceptible barnyardgrass (S-BYG) response to propani
l alone at similar rates was 52, 73, 88, and 94% control. HOE 30374, carbar
yl, piperophos, or pendimethalin in combination with propanil produced syne
rgistic effects on R-BYG. For each compound tested, at least one rate combi
nation with propanil controlled R-BYG > 80% with minimal rice injury (< 20%
) at 7 DAT. Use of these combinations of compounds could provide more effec
tive control of this resistant biotype and help prevent its spread.