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

A single dominant mutation conferring resistance to aryloxyphenoxypropionat e (AOPP) and cyclohexanedione (CHD) herbicides was incorporated into a quan titative model for the population development of Alopecurus myosuroides Hud s. 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/CH D herbicides which kill 90% of susceptible but no resistant plants, a thres hold of 10 plants m (2) surviving herbicides ('field resistance') will deve lop: in 9 10 years if all tillage is by tine cultivation to 10 cm deep: aft er 28-30 years of annual ploughing: in 12 years if tine cultivations are in terspersed with ploughing once every 4 years. if AOPP/CHD herbicides are al ternated with herbicides with different modes of action, outcomes depend on the annual kill rate: with 95% kill (of susceptible plants by AOPP/CHDs an d all plants by alternative herbicides) and tine cultivation, field resista nce develops in 22 years, however, resistance can be delayed for 45 years i f AOPP/CHDs are rotated with two additional herbicides, each with a differe nt mode of action. The model predictions on the number of years required fu r field resistance to develop are not highly sensitive to the density of th e seedbank or the initial frequency of resistance.