The UK has always had its share of invasive species be it flora or fauna. Some like the grey squirrel and Himalayan balsam are well know but due to its greater frequency there is increasing concern for two weed grasses often hidden in a range of plants sown in bird food mixes so they often go un-noticed.

The grasses in question go by many different English names Barn Yard Grass (Echinochloa.spp. Generally Echinochloa crus-galli or Echinochloa frumentacea) and Bristle Grass (Setaria viridis).

Thought to generally come in continental supplies of such seeds as Millet or Sorghum. They are both annuals with prolific seed production. Selective control is possible in single species crops such as maize but thins get more complicated in multi species mixes

Thoughts on control

Flower mixes

Annual grass weeds are easy to control in perennial flower or pollen and nectar mixes. Mow as often as necessary in the first year to reduce the seed set and competition from the annuals.

Bird food mixes

Cutting is not an option as it destroys the annual sown species. Bird food mixes contain a wide range of sown species making selective weed control difficult or impossible. A known weed problem may allow species to be selected that are tolerant to a specific herbicide. Some weeds provide seeds for birds but best if not at the expense of the sown species.

Herbicides are a management tool and have a place but agreements and product labels must be followed. Weeds build up after a few years of sowing in the same place and eventually the site needs to be returned to cropping to be “cleaned up”.

Herbicides

The following does not represent any form of recommendation but may point to products worth investigating. Stewardship agreements require a minimum number of visible sown species and a derogation prior to treatment and product labels need to be followed at all times.

The following products may offer a degree of selective grass weed control with some sown species survival depending on the sown species.

• Cereal based Oskar, Atlantis.
• Maize based Calaris, Calisto, Dual Gold, Maister, Sampson Extra.
• Mixes containing cereals, Millet, Kale and Sorghum
  Some damage may occur to some species but the following are worth checking:
• Crystal Cereals, Millet, Sorghum, Kale some damage.
• Smelter/Dual Gold Kale ok. Cereals and Sorghum some damage. Millet is killed.