Development of an Agar Bioassay Sensitivity Test in Alopecurus myosuroides for the Pre-Emergence Herbicides Cinmethylin and Flufenacet

Abstract

Rapid and reliable tests for pre-emergence herbicide susceptibility in weeds are important to test a wider range of accessions on their baseline sensitivity, as well as to provide information on putative resistance. This study focused on the development of an agar quick test to determine sensitivity differences in Alopecurus myosuroides Huds. to pre-emergence herbicides containing flufenacet and cinmethylin. The new agar quick test and a standardized whole plant pot bioassay were conducted twice in 2019. For both test systems, seeds of 18 populations of A. myosuroides originated from Southwest Germany and Great Britain were used and treated with discriminating rates of herbicides in dose-response studies. After 28 days, the above-ground dry matter of the plants was determined and the resistance factors were calculated. The agar test was able to provide information on the resistance status of the tested biotype within 12 days. All populations did not show reduced sensitivity to cinmethylin. Within three populations, differences in sensitivity levels were observed between the two test systems. As cinmethylin is not yet marketed in Europe, these resistance factors can also be considered as a baseline sensitivity for A. myosuroides. For flufenacet, the resistance factors differed significantly from the whole plant pot bioassay and the agar test for the biotypes A (0.35, 13.1), C (0.56, 13.2), D (1.87, 12.4), E (15.5, 3.5) and H (2.95, 14). It was possible for the most part for the cinmethylin tested populations to confirm the results of the standardized whole plant pot bioassay in the agar bioassay sensitivity tests, and hence create a promising, faster test system.

Inhibition of acyl‐ACP thioesterase as site of action of the commercial herbicides cumyluron, oxaziclomefone, bromobutide, methyldymron and tebutam

“…Indeed, it was shown that multipleherbicide resistant biotypes of Lolium rigidum or Alopecurus myosuroides biotypes with resistance to flufenacet can be effectively controlled by cinmethylin. [38][39][40] Identification of alternative FAT inhibitors for use in wheat or other crop systems will strengthen and diversify the tools for weed management. The herein identified new FAT inhibitors lay the groundwork for the development of new herbicides with this newly identified SoA.…”

“…For the control of increasing numbers of herbicide resistant weeds with target site or non‐target site resistances, there is a dire need for new active ingredients and ideally SoAs. Indeed, it was shown that multiple‐herbicide resistant biotypes of Lolium rigidum or Alopecurus myosuroides biotypes with resistance to flufenacet can be effectively controlled by cinmethylin 38–40 . Identification of alternative FAT inhibitors for use in wheat or other crop systems will strengthen and diversify the tools for weed management.…”

Modern Approaches for the Development of New Herbicides Based on Natural Compounds

“…Among the monocot plants, the use of Agrostis stolonifera L. and Alopecurus myosuroides Huds. seeds [ 35 , 36 ], as well as several species of aquatic macrophytes of the genus Lemna (e.g., L. paucicostata Hegelm., L. minor L., L. gibba L.) [ 37 , 38 ], was adapted for bioassays. In the screening programs conducted by Chinese researchers, Brassica campestris L., Cucumis sativus L., Amaranthus retroflexus L., Digitaria sanguinalis (L.) Scop., Echinochloa crus-galli L.) P. Beauv.…”

Early detection, herbicide resistance screening, and integrated management of invasive plant species: a review

“…99 In Table 4, several recent onfarm, portable, and rapid diagnostic tests for herbicide resistance reported after 2013 are presented in detail to assist the screening of IPS for putative herbicide resistance. Some tests require that the environmental parameters remain stable to provide valid results, 100 while others require cutting-edge sensors and technologies to deliver more robust results. 101 Indicative new technologies, tests, methods, techniques and applications for early weed detection and rapid herbicide resistance screening are presented in Tables 4 and 5.…”