Wild Oats

Avena fatua

Wild Oats (Avena fatua) Wild oats are a common and very damaging weed that can occur in many crops. Capable of germinating at any time of year, they will just as successfully grow and compete in winter cereals as in a spring planted crop like peas. Left uncontrolled wild oats will quickly grow into large, multi-tillered, competitive grass weeds. Due to their competitive nature very few plants per square metre are needed before it becomes economic to control them.

Depending upon the crop controlling 5-10 wild oats per square meter will result in an economic response. Wild oats also produce a large number of long-lived seeds, often as many as 150 per panicle with many panicles per plant. Wild oat seeds can remain viable in the soil for several years and the common saying “one year’s seeding, 7 years weeding” stands very true for wild oats. Wild oats can be successfully controlled with selective herbicides such as Puma S. However, if numbers are low hand rogueing should be undertaken if possible.

Related Pests

Amaranthus - Red Root

Amaranthus powellii

Commonly known as redroot, amaranthus (Amaranthus powellii) is a serious weed of maize, other crops and orchards and is widespread throughout New Zealand. It can grow up to 1 m in height and is characterised by red coloured stem.

Barnyard Grass

Echinochloa-crus-galli

Though barnyard grass (Echinochloa-crus-galli) is mainly found on the North Island it can now be found on the South Island as far south as South Canterbury. Barnyard grass germinates in the spring when temperatures increase. Barnyard grass is very competitive and invades a range of crops. When small, barnyard grass can be identified by its upright habit, rolled leaves and lack of ligules or auricles. When seed-heads are present they are quite distinct being open and with dark brown seeds.

Yellow Bristle Grass

Setaria pumila

Yellow bristle grass (Setaria pumila) or YBG is one of a number of related species found in New Zealand and is widespread across parts of the North Island. It is a particular problem when it infests pasture as over time it out competes and replaces more productive species. YBG germinates in late spring as temperatures rise and grows quickly setting a large number of seeds from December onwards. Look for young plants in “gaps” in pasture. They have light green leaves with red bases and an upright habit. The seedhead is cylindrical, up to 10 cm long and yellowish in colour due to the bristles associated with each spikelet.

Lesser Canary Grass

Phalaris minor

Lesser canary grass (Phalaris minor) is originally from the Mediterranean and is now a common, annual grass weed of winter planted cereal crops. Seeds germinate throughout the year with the leaves being non-hairy, rough and long, tapering to a fine point. The ligule is long and finely serrated, auricles are absent. When in ear the short, stubby panicle (1.5 - 6 cm x 1.2 – 2.2 cm) is quite distinct and makes a good identification feature.

Barley Grass

Hordeum murinum

Barley grass (Hordeum murinum) is a competitive annual grass that is increasingly being found in pasture. Once in ear the grass is straight forward to identify looking distinctly like barley to which it is related. When young the leaves tend to be light green, rough and often twisted. The leaf base has a short ligule and long, narrow spreading auricles. When mature, the ear readily breaks up and adheres to animal fur and clothing which ensures it spreads very effectively.