Amoung the most competitive weeds with just 1 plant/m² reducing yield by 1%. Seeds can remain viable in the soil for long periods, up to 10 years in undisturbed land and 4-5 years in cultivated soil. Herbicide resistance is a major issue.
Some of the most familiar weeds, both wild oat and winter wild oat are tall, stout annual grasses similar to the cultivated or 'tame' oat. Very similar species, both have large loose drooping seed head or panicle. Wild oat is 30-150 cm and germinates in both autumn and spring, although the majority of seeds germinate in the spring. Winter wild oat is a stouter plant 60-180 cm and germinates in the late autumn and winter. It is very difficult to tell the species apart but they can be differentiated on the basis of their spikelet characteristics.
Leaf blades: Broad, flat and rough. Viewed from above, there is an anti-clockwise twist even apparent in seedlings at 2 - 3 leaf stage.