Abstract (inglese)

Some of the worst herbicide resistance problems in Italy are found in arid and semi-arid areas in the centre and south. These areas are often characterised by poor soils, rainfall concentrated during the winter and simplified agriculture systems where durum wheat is the main crop, often monoculture. In some areas there are no alternative cash crops, while in others tomato and sugarbeet are rotated with the cereal. However, there is frequently no rotation of herbicide mode of action.
Six species have evolved resistant populations: four grasses — Avena sterilis (first report in 1992), Lolium spp. (1995), Phalaris paradoxa (1998) and P. brachystachys (2001) — and two dicots — Papaver rhoeas (1998) and Sinapis arvensis (2006).
Most grass populations are resistant to ACCase-inhibitors (by altered target site or enhanced metabolism) and some are multiple resistant to ALS-inhibitors. The two dicots show target site resistance to ALS inhibitors: some P. rhoeas populations are multiple resistant to ALS-inhibitors and auxin-like herbicides and some only to the latter group. The two worst situations involve Lolium spp. and P. rhoeas.
In the situation described above, management of herbicide resistant populations is problematic as a limited number of anti-resistance agronomic techniques are applicable. Most farmers manage resistance by rotating herbicide mode of action. The increasing use of graminicide sulfonylureas is becoming a threat, so farmers and stakeholders need to be aware that a more cautious and responsible use of herbicides is crucial. The Italian herbicide resistance working group (GIRE) is strongly committed to this aim.