Cunning planning needed as resistance grows and armoury dwindles

The main cost to agriculture is seen in yield losses which, in winter wheat, can be as much as 25% where black-grass populations have not responded to chemical control. Likewise, poorer control of fungal pathogens, such as Septoria tritici, can increase yield losses.  For example, up to 20% yield losses are typical in untreated crops with Septoria, although this can increase to 30-50% in untreated susceptible varieties in epidemic years. 

Maintaining effective control is vital. But the battle against pesticide resistance is a complex struggle with nature as mutations in the genetic structure of the weed or fungal pathogen continually develop to counter the action of the applied pesticide.