Managing Herbicide-resistant Blackgrass (Alopecurus Myosuroides): Theory and Practice

Blackgrass is the most important herbicide-resistant weed in Europe, occurring in 10 countries. Enhanced metabolism is the most common mechanism, conferring partial resistance to a wide range of herbicides, but acetyl-CoA carboxylase (ACCase) target-site resistance also occurs widely. Recently, acetolactate synthase (ALS) target-site resistance conferred by a Pro197 mutation was identified in blackgrass in England and is of concern because of increasing use of sulfonylurea herbicides such as mesosulfuron + iodosulfuron. Resistance management strategies encourage (1) greater use of cultural control measures such as plowing, crop rotation, and delayed drilling; (2) reduced reliance on high-risk herbicides (ACCase, ALS); and (3) use of mixtures and sequences of herbicides with different modes of action. A key message is that, as weeds are relatively immobile, preventing and managing herbicide resistance is largely within the individual farmer's own control. In practice, financial and environmental pressures limit the scope for more cultural control, and the European Community Pesticide Review will result in fewer alternative herbicides being available. Consultants often feel unable to recommend lower risk but weaker herbicide strategies to farmers because the amount of blackgrass remaining might be unacceptable. This dilemma is exemplified by the recent introduction of a formulated mixture of mesosulfuron + iodosulfuron, which has given outstanding control of blackgrass. Farmers expect new herbicides to become available, but this optimistic view appears misplaced. A primary aim is to continue to encourage farmers to integrate cultural and chemical control in a long-term strategy. Nomenclature: Iodosulfuron-methyl-sodium (proposed), [methyl 4-iodo-2-[3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-ureidosulfonyl]benzoate, sodium salt]; mesosulfuron-methyl (proposed), [methyl 2-[3-(4,6-dimethoxypyrimidin-2-yl)ureidosulfonyl]-4-methanesulfonamidomethylbenzoate]; blackgrass, Alopecurus myosuroides Huds. ALOMY.

[1]  J. Gressel,et al.  Are Herbicide mixtures useful for Delaying the Rapid Evolution of Resistance? a Case Study , 1994, Weed Technology.

[2]  S. Moss,et al.  The influence of tillage on the weed flora in a succession of winter wheat crops on a clay loam soil and a silt loam soil , 1982 .

[3]  K. Cocker,et al.  Multiple Mechanisms of Resistance to Fenoxaprop-P-Ethyl in United Kingdom and Other European Populations of Herbicide-Resistant Alopecurus myosuroides (Black-Grass) , 1999 .

[4]  J. Hall,et al.  Management strategies for attenuating herbicide resistance: untoward consequences of their promotion , 2000 .

[5]  L. Field,et al.  Characterisation of target-site resistance to ACCase-inhibiting herbicides in the weed Alopecurus myosuroides (black-grass). , 2003, Pest management science.

[6]  C. Mallory-Smith,et al.  Physiological and molecular basis for ALS inhibitor resistance in Bromus tectorum biotypes , 2004 .

[7]  N. Colbach,et al.  Evaluation of cropping systems for management of herbicide-resistant populations of blackgrass (Alopecurus myosuroides Huds.). , 2001 .

[8]  H. Beckie,et al.  Screening for Herbicide Resistance in Weeds1 , 2000, Weed Technology.

[9]  R. Prado,et al.  Diclofop-methyl Cross-Resistance in a Chlorotoluron-Resistant Biotype ofAlopecurus myosuroides , 1996 .

[10]  M. Shaw,et al.  When can reduced doses and pesticide mixtures delay the build-up of pesticide resistance? A mathematical model , 1997 .

[11]  P. Tranel,et al.  Resistance of weeds to ALS-inhibiting herbicides: what have we learned? , 2002 .

[12]  J. D. Nalewaja,et al.  Cultural Practices for Weed Resistance Management , 1999, Weed Technology.

[13]  L. Field,et al.  An isoleucine to leucine substitution in the ACCase of Alopecurus myosuroides (black-grass) is associated with resistance to the herbicide sethoxydim , 2002 .

[14]  J. L. P. Oorschot,et al.  Use of fluorescence induction to diagnose resistance of Alopecurus myosuroides Huds. (black‐grass) to chlorotoluron , 1992 .

[15]  Moss.  The effect of drilling date, pre-drilling cultivations and herbicides on Alopecurus myosuroides (black-grass) populations in winter cereals. , 1985 .

[16]  N. Colbach,et al.  How to model the effects of farming practices on weed emergence , 2005 .

[17]  I. Heap.  International survey of herbicide-resistant weeds , 1997 .

[18]  S. Powles,et al.  Molecular Bases for Sensitivity to Acetyl-Coenzyme A Carboxylase Inhibitors in Black-Grass1 , 2005, Plant Physiology.

[19]  S. Moss,et al.  Guidelines for the prevention and control of herbicide-resistant black-grass (Alopecurus myosuroides Huds.) , 1994 .

[20]  A. Cobb,et al.  New, quick tests for herbicide resistance in black-grass (Alopecurus myosuroides Huds) based on increased glutathione S-transferase activity and abundance. , 2002, Pest management science.

[21]  A. J. Swain,et al.  Improving crop profitability by using minimum cultivation and exploiting grass weed ecology. , 2006 .

[22]  Maurice B. Green,et al.  Managing resistance to agrochemicals : from fundamental research to practical strategies , 1990 .

[23]  J. H. Clarke,et al.  The occurrence of herbicide-resistant grass-weeds in the United Kingdom and a new system for designating resistance in screening assays , 1999 .

[24]  P. Boutsalis.  Syngenta Quick-Test: A Rapid Whole-Plant Test for Herbicide Resistance1 , 2001, Weed Technology.

[25]  J. Orson.  The Cost to the Farmer of Herbicide Resistance , 1999, Weed Technology.

[26]  Letouzé,et al.  A pollen test to detect ACCase target‐site resistance within Alopecurus myosuroides populations , 2008 .

[27]  F. Gould.  Comparisons Between Resistance Management Strategies for Insects and Weeds , 1995, Weed Technology.

[28]  Kemp,et al.  Herbicide resistance in Alopecurus myosuroides , 1990 .

[29]  S. Moss,et al.  Mechanism of resistance to chlorotoluron in two biotypes of the grass weed Alopecurus myosuroides. , 1995 .

[30]  J. Gasquez,et al.  A rapid reliable test for screening aryloxyphenoxypropionic acid resistance within Alopecurus myosuroides and Lolium spp. populations , 1999 .