Efficacy of Preemergence Herbicides for Controlling a Dinitroaniline-Resistant Goosegrass (<i>Eleusine indica</i>) in Georgia

Abstract

Goosegrass is a problematic weed in turfgrass, and overuse of dinitroaniline (dna) herbicides has resulted in evolution of resistant populations. The objectives of this research were to (1) evaluate responses of a susceptible (S) goosegrass compared to a suspected resistant (R) biotype from Griffin, GA to prodiamine, and (2) evaluate efficacy of various PRE herbicides for control. Prodiamine rates required for 50% control and 50% shoot reductions after 6 wk for R-goosegrass measured &gt; 13.44 and 3.2 kg ai ha −1 , respectively, whereas rates for the S-population measured 0.45 and &lt; 0.42 kg ha −1 , respectively. In field experiments, sequential applications of dithiopyr and prodiamine provided &lt; 20% control of R-goosegrass over 2 yr. Single applications of dimethenamid-P at 1.68 kg ai ha −1 provided &lt; 50% goosegrass control in 2011 but provided excellent control (≥ 90%) at 7 mo after initial treatments (MAIT) in 2012. Single and sequential applications of indaziflam provided excellent control of goosegrass in both years, and oxadiazon controlled goosegrass &gt; 85% at 7 MAIT in 2011 and ≥ 90% in 2012. Single and sequential PRE sulfentrazone applications controlled goosegrass &lt; 60% in 2011 but averaged 94% control in 2012. Overall, indaziflam and oxadiazon provided good (80 to 89%) to excellent control of dna-resistant goosegrass in both years, but dimethenamid and sulfentrazone were inconsistent.