Modelling different cultivation and herbicide strategies for their effect on herbicide resistance in Alopecurus myosuroides

A single dominant mutation conferring resistance to aryloxyphenoxypropionate (AOPP) and cyclohexanedione (CHD) herbicides was incorporated into a quantitative model for the population development of Alopecurus myosuroides Huds. The model predicts that from an initial seedbank of 100 seed m (2), 10 (6) of which mutate to resistance each generation, and annual use of AOPP/CHD herbicides which kill 90% of susceptible but no resistant plants, a threshold of 10 plants m (2) surviving herbicides ('field resistance') will develop: in 9 10 years if all tillage is by tine cultivation to 10 cm deep: after 28-30 years of annual ploughing: in 12 years if tine cultivations are interspersed with ploughing once every 4 years. if AOPP/CHD herbicides are alternated with herbicides with different modes of action, outcomes depend on the annual kill rate: with 95% kill (of susceptible plants by AOPP/CHDs and all plants by alternative herbicides) and tine cultivation, field resistance develops in 22 years, however, resistance can be delayed for 45 years if AOPP/CHDs are rotated with two additional herbicides, each with a different mode of action. The model predictions on the number of years required fur field resistance to develop are not highly sensitive to the density of the seedbank or the initial frequency of resistance.