Current Status of Herbicide Resistance in the Iberian Peninsula: Future Trends and Challenges

The evolution of herbicide resistance in weeds has emerged as one the most serious threats to sustainable food production systems, which necessitates evaluation herbicides determine their efficacy. first case Iberian Peninsula was reported about 50 years ago, wherein Panicum dichotomiflorum found be resistant (R) atrazine Spanish maize fields. Since then, evolved 33 weed species, representing a total 77 single-herbicide-resistance cases this geographic area: 66 Spain and 11 Portugal. Changes agricultural practices, namely adoption non-tillage systems increased use herbicides, led selection biotypes wide range herbicides. Nowadays important crops Portugal (maize, winter cereals, rice, citrus, fruits, olive orchards) are affected, with several mechanisms action (MoAs), namely: ALS inhibitors (20 species), ACCase (8 PS II (18 synthetic auxin (3 species). More recently, fast increase EPSPS-inhibiting glyphosate been remarkable, species already having last 10 Peninsula. diversity mechanisms, both target-site non-target-site, responsible for different MoAs, involving point mutations target site enhanced rates detoxification, respectively. 13 multiple-herbicide resistance, three three–four five MoAs. Future research perspectives should further study relationship between management strategies occurrence TSR NTSR improve design, develop monitoring diagnostic tools deepen resistance.