Silky bentgrass (Apera spica-venti)

Test on a resistant population of silky bentgrass with Husar (lodosulfuron). Plants survive at a dosage up to 4 times higher than the approved dose.
O = water control, N = approved dose, 2N = double the approved dose, 4N = quadruple the approved dose

Resistance status in Switzerland

In silky bentgrass populations, three herbicide modes of action are affected by resistances. Since the start of the monitoring programme begun in 2011, the ALS-inhibitor mode of action of the HRAC 2 group is the one exhibiting the most resistances.

The first case of resistance to ALS inhibitors in a silky bentgrass population in Switzerland was confirmed in 2006 in the Canton of Vaud. In this species, resistances to this mode of action are by far the most common in Switzerland, and the examined cases generally exhibit a very strong resistance.

Several cases of double resistances to ACCase- and ALS-inhibiting herbicides (HRAC 1 and HRAC 2, respectively) have been confirmed since the start of the monitoring programme. The first case dates from 2013 in the Canton of Vaud.

The first case of double resistance to ASL inhibitors (HRAC 2) and photosystem II inhibitors (HRAC 5) was also confirmed in 2013 in the Canton of Vaud. Several more cases then followed the first.

Plant characteristics

Silky bentgrass (Apera spica-venti)

Annual or biennial monocot of the Poaceae family

Colonised crops

Mainly winter cereals

Favourable conditions
for development

Winter-cereal-heavy rotations, infrequent ploughing

Preferred soils

Sandy or silty-sandy, moist, slightly acid, nitrogen-rich. An indicator plant for soils clogged with organic matter of vegetable origin undergoing fossilisation.

Germination window




EPPO code



Resistance Maps