02701naa a2200217 a 450000100080000000500110000800800410001910000190006024501400007926000090021952019270022865300190215565300210217465300250219565300240222065300150224470000180225970000140227770000220229177301700231311249892016-04-15       2016    bl uuuu     u00u1 u    #d1 aMARTINS, B. A.  aCROSS- AND MULTIPLE-RESISTANCE IN BARNYARDGRASS (ECHINOCHLOA CRUS-GALLI) POPULATIONS FROM RICE FIELDS IN BRAZIL.h[electronic resource]  c2016  aSeeds from two E. crus-galli populations (ECH73 and ECH77) that survived a quinclorac application were collected in two rice production fields from Santa Catarina State, Brazil. The rice fields had a history of quinclorac and ALS inhibitor use for more than 10 years. Quinclorac wholeplant dose-response and ALS inhibitor screening studies were conducted in the greenhouse. Treatments were applied under the same conditions in both studies, with a known susceptible population (SUS) included. The variables evaluated were percent dry weight for the dose-response study and percent visual control for the screening study, both evaluations were 21 days after treatment (DAT). Results confirmed quinclorac susceptibility in SUS and that the suspected resistant populations ECH73 and ECH77 were quinclorac-resistant. For the labeled use rate, percent dry weight for SUS was less than 35%, whereas for ECH73 and ECH77 percent dry weight was nearly 70% and 100%, respectively. For the herbicide screening experiment, SUS was controlled by all herbicides at the field rate. ECH73 and ECH77 were resistant to imazethapyr and bispiribac-sodium, but were not resistant to penoxsulam, to the formulated mixture imazapic+imazapyr or to the mixtures fenoxaprop-p-ethyl+penoxsulam or fenoxaprop-pethyl+bispiribac-sodium. Thus, the latter herbicides could be used to manage E. crus-galli in the sampled rice fields. Results from the dose-response and the screening experiments indicate that populations ECH73 and ECH77 possess multiple-resistance to two modes of action groups (synthetic auxins and ALS inhibitors) and have the same cross-resistance patterns to two ALS inhibitors, imazethapyr and bispiribac-sodium. Absorption, translocation and metabolism studies using radiolabeled quinclorac and ALS inhibitors are being conducted to investigate non-targetsite-based mechanisms of resistance in the Echinochloa crus-galli population.  aALS inhibitors  across-resistance  ametabolic resistance  amultiple-resistance  aquinclorac1 aNOLDIN, J. A.1 aKARAM, D.1 aMALLORY-SMITH, C.  tIn: 2016 ANNUAL MEETING OF THE WEED SCIENCE SOCIETY OF AMERICA, 2016, San Juan, Puerto Rico. Abstracts... Lawrence, KS: Weed Science Society of America, 2016. p. 252