Controlling Dinitroaniline-Resistant Goosegrass (Eleusine indica) in Turfgrass
Breeden, S.M., Brosnan, J.T., Breeden, G.K., Vargas, J.J., Eichberger, G., Tresch, S., Laforest, M. (2017). Controlling Dinitroaniline-Resistant Goosegrass (Eleusine indica) in Turfgrass, 31(6), 883-889. http://dx.doi.org/10.1017/wet.2017.57
Plain language summary
Prodiamine and dinitroaniline are used to control goosegrass in turf. Goosegrass plants suspected of herbicide resistance were harvested at golf courses in Maryville, Tennessee. The genetic cause of resistance was identified. Also, it was shown that the weed can be controlled with topramezone. The knowledge of the mechanism allowed us to create a genetic test allowing the rapid diagnosis of similar cases of resistance of goosegrass. This test provides a rapid confirmation of the resistance and informs the producer so that he can make the best decision in his cultural practice.
© Weed Science Society of America, 2017.. Prodiamine is a dinitroaniline herbicide labeled for PRE control of goosegrass in warm- A nd cool-season turfgrass. In 2013, several golf course roughs in Maryville, TN reported poor goosegrass control (< 20%) following prodiamine treatment at 1,120 g ai ha-1. We harvested suspected prodiamine-resistant (PR) and prodiamine-susceptible (S) goosegrass phenotypes from the field and exposed them to a range of increasing prodiamine concentrations in hydroponic culture. Exposure to prodiamine at 0.001mM reduced root growth of the S phenotype to 11% of the non-treated check. By comparison, exposure to 0.001mM prodiamine had minimal effect on the PR phenotype, as root growth was 94% of the non-treated check. Molecular analyses revealed that PR plants contained a threonine (Thr) to isoleucine (Ile) substitution at position 239 on the α-tubulin 1 (TUA1) protein. The substitution, found in all PR plants, is the mechanism of prodiamine resistance in this phenotype. In field studies, topramezone controlled PR goosegrass 72% to 89% by 50 d after treatment (DAT) compared to only 22% to 23% for foramsulfuron. Topramezone treatment injured bermudagrass 34% to 60% from 7 to 14 DAT; however, injury was ≤6% 28 DAT and 0% by the end of the study. Our results indicate that POST applications of topramezone can control dinitroaniline-resistant goosegrass. In addition, we established an easy-to-use genotyping assay to quickly screen goosegrass phenotypes for a target-site mutation (Thr-239-Ile) on TUA1 associated with resistance to dinitroaniline herbicides such as prodiamine. Future research should work to expand this assay for use with other weed species and herbicidal modes of action. Nomenclature: Foramsulfuron; prodiamine; topramezone; goosegrass, Eleusine indica L. Gaertn.; bermudagrass, Cynodon dactylon L. Pers.