<b>HRAC Group 2</b> <font size='2'> (Legacy B) </font> resistant Panicum miliaceum var. ruderale Kitag. from China

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 2 (LEGACY B) RESISTANT WILD PANICGRASS
(Panicum miliaceum var. ruderale Kitag.)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

China, Liaoning Province

INTRODUCTION		WILD PANICGRASS
Wild Panicgrass (Panicum miliaceum var. ruderale Kitag.) is a monocot weed in the Poaceae family. In China this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2023 and infests Corn (maize). Group 2 (Legacy B) herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ). Research has shown that these particular biotypes are resistant to nicosulfuron and they may be cross-resistant to other Group 2 (Legacy B) herbicides. The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.

QUIK STATS (last updated Aug 05, 2023 )
Common Name	Wild Panicgrass
Species	Panicum miliaceum var. ruderale Kitag.
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicides	nicosulfuron
Location	China, Liaoning Province
Year	2023
Situation(s)	Corn (maize)
Contributors - (Alphabetically)	Ian Heap
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NOTES ABOUT THIS BIOTYPE

GENERAL

Enhanced metabolic ability enabled wild panicgrass (Panicum miliaceum L. var. ruderale kit.) resistance to ALS inhibitor herbicide.

Author(s) : Guan YiDi ; Cao ShihAn ; Zou YiZe ; Liu LiRu ; Yang ChangBi ; Ji MingShan

Author Affiliation : College of Plant Protection, Shenyang Agricultural University, No. 120 Dongling Road, Shenhe District, Shenyang City 110866, China.

Author Email : jimingshan@163.com

Journal article : Pesticide Biochemistry and Physiology 2023 Vol.194 ref.23

Abstract : Wild panicgrass (Panicummiliaceum L. var. ruderale kit.) is an annual grass weed that primarily occurs in maize fields. Nicosulfuron is a widely used selective herbicide that effectively controls gramineous weeds in maize fields. However, owing to its long-term and extensive application, the control of P. miliaceum has been substantially reduced. The objective of this study was to determine the resistance pattern to ALS inhibitors in P. miliaceum and investigate the underlying resistance mechanisms. These are important for guiding the prevention and eradication of resistant weeds. Whole plant bioassays showed P. miliaceum had evolved high levels of resistance to nicosulfuron and multiple resistance to atrazine and mesotrione. The ALS gene sequence results indicated the absence of mutations in the resistant population. Additionally, there was no significant difference found in the inhibition rate of the ALS enzyme activity (I₅₀) between the resistant and sensitive populations. Following the application of malathion the resistant P. miliaceum population became more sensitive to nicosulfuron. At 96 h after application of nicosulfuron, glutathione-S-transferase activity in the resistant population was significantly higher than that in the susceptible population. The study reveals that the main cause of resistance to ALS inhibitor herbicide in P. miliaceum is likely increased metabolism of herbicides. These findings may assist in devising effective strategies for preventing and eliminating resistant P. miliaceum.

ISSN : 0048-3575

DOI : 10.1016/j.pestbp.2023.105510

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Wild Panicgrass biotype with this Wild Panicgrass biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetics

Genetic studies on HRAC Group 2 resistant Wild Panicgrass indicate that the inheritance is determined by a dominant trait. There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature

Mechanism of Resistance

Studies on the mechanism of resistance of Group 2 (Legacy B) resistant Wild Panicgrass from China indicate that resistance is due to enhanced metabolism. There may be a note below or an article discussing the mechanism of resistance in the Fact Sheets and Other Literature

Relative Fitness

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes. If you have any information pertaining to the fitness of Group 2 (Legacy B) resistant Wild Panicgrass from China please update the database.

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CONTRIBUTING WEED SCIENTISTS

IAN HEAP

Director International Survey of Herbicide-Resistant Weeds P.O. Box 1365 Corvallis, 97339, Oregon United States Email Ian Heap Web : Web Site Link

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in China have been instrumental in providing you this information. Particular thanks is given to Ian Heap for providing detailed information.

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Herbicide Resistant Wild Panicgrass Globally
(Panicum miliaceum var. ruderale Kitag.)

Country

FirstYear

Situation

Active Ingredients

Site of Action

China

2023

Corn (maize)

nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Literature about Similar Cases

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Swanton, C. J. ; Chandler, K. ; Elmes, M. J. ; Murphy, S. D. ; Anderson, G. W.. 1996. Postemergence control of annual grasses and corn (Zea mays) tolerance using DPX-79406. Weed Technology 10 : 288 - 294.

DPX-79406, a 1:1 premix of nicosulfuron and rimsulfuron, was evaluated for post-em. (POST) annual grass weed control in both controlled environment and field experiments (the latter conducted at Elora and Woodstock, in Ontario). In controlled environment experiments, green foxtail (Setaria viridis) was most susceptible to DPX-79406, whereas yellow foxtail (S. glauca) was the least susceptible of the species evaluated. DPX-79406 at 12 g/ha completely controlled six-leaf black-seeded proso millet (Panicum miliaceum), yellow foxtail, green foxtail, and barnyardgrass (Echinochloa crus-galli). In the field, DPX-79406 at 3.0 to 25.0 g/ha effectively controlled annual grass weeds without injury to three- to six-leaf corn [maize] cv. Pioneer 3851 and Pioneer 3790. There was more variation in the effectiveness of DPX-79406 applied in the field. Early POST applications provided less weed control than late application, especially for barnyardgrass, because of weeds emerging after application. As a result, higher doses were sometimes needed for effective control. In weed-free field trials at both sites in 1990 and 1991, corn tolerated doses up to 75 g/ha of DPX-79406 applied at the three- to six-leaf growth stage. However, doses as low as 18.8 g/ha applied at the six- to nine-leaf growth stage reduced grain yield. In 1991, corn tillering increases, and height and yield reductions were related linearly to the dose of DPX-79406 applied during later growth stages. It was concluded that DPX-79406 should be applied early POST in order to avoid crop injury while providing effective weed control..

Miller, T. W. ; Callihan, R. H.. 1995. Interference between triazine-resistant Brassica napus and Panicum miliaceum. Weed Research (Oxford) 35 : 453 - 460.

Atrazine carryover often limits growers to production of atrazine-tolerant crops the year following application, and allows the increase of triazine-tolerant weed species such as Panicum miliaceum (wild proso millet). Triazine-resistant Brassica napus cv. Triton (oilseed rape) was tested to characterize the nature of interspecific interference with P. miliaceum. In a greenhouse study, atrazine at 2.2 kg ha^-1 depressed oilseed rape fruit (siliqua) number and fruit dry weight, and delayed flowering, but did not significantly affect height or weight of shoots. Oilseed rape fruit weight was reduced at 200 P. miliaceum plants m^-2, fruit number and shoot weight were inhibited at 400 weeds m^-2, and height was reduced and flowering delayed at 600 weeds m^-2. Number and weight of fruits were reduced by one-third after 8 weeks of interference as compared to oilseed rape grown with the weed for 4 weeks. Oilseed rape height was reduced by 29% and shoot weight by 55% by 600 weeds m^-2 and 2.2 kg ha^-1 atrazine, while fruit number and weight were reduced by 72%. Oilseed rape shoot weight was reduced by 74% by 600 weeds m^-2 for 12 weeks of interference, while fruit number and weight were reduced by 85 and 82%, respectively. In a field study, fluazifop reduced early season P. miliaceum cover by 72%, but did not increase oilseed rape cover. Midseason P. miliaceum shoot weight was decreased by 97% by fluazifop and oilseed rape shoot weight was increased by 34%. P. miliaceum control increased oilseed rape biomass by 38% at 89 days, but biomass of oilseed rape sown at 11.2 kg ha^-1 with 2.12 kg atrazine ha^-1 was not decreased by P. miliaceum interference at 89 days..

Crosbie, S. H. ; Greulach, L. K. ; Reynolds, D. A.. 1994. Post emergence control of giant foxtail (Setaria faberi), wild proso millet (Panicum miliaceum), and woolly cupgrass (Eriochloa villosa) in sethoxydim resistant corn. : 59 - 60.

Field trials were conducted in North Carolina to assess total weed control by 0.048-0.28 lb/acre sethoxydim tank mixtures. Results indicated that excellent control of giant foxtail, woolly cupgrass and large crabgrass [Digitaria sanguinalis] was achieved with 0.19 lb sethoxydim + crop oil concentrate, 28% UAN [urea ammonium nitrate] or nonionic surfactant. No consistent antagonism by sethoxydim at 0.19 lb in mixtures with 2,4-D, bentazone, atrazine, primisulfuron, dicamba, bromoxynil and thifensulfuron was identified for these 3 weed species. However, sethoxydim + bentazone mixtures gave poorest control of giant foxtail, yet better control was achieved with all sethoxydim + broadleaved herbicide mixtures than with a 0.03 lb nicosulfuron + 0.25 lb bromoxynil treatment. No injury or effects on yield in the maize crop were observed, even with 0.28 lb sethoxydim, for either resistant (85-day Asgrow, and 105- and 109-day Dekalb cultivars) or susceptible lines. The results of trials to evaluate single and split sethoxydim + broadleaved weed herbicide treatments for control of wild proso millet are summarized; it was concluded that sethoxydim outperformed nicosulfuron, and that a pre-em. metolachlor treatment did not improve control..

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