Summergrass or Crabgrass
Summer Grass (Digitaria sanguinalis) is a member of the Digitaria family, and also known as Crabgrass. This discusses how to identify this weed and options to control it.
Jerry Spencer 
Why is Summer Grass a Problem Weed?
- Summer grass (also known as crabgrass) is a problem weed because it’s a fast-growing, aggressive annual grass.
- It spreads rapidly through seeds and stolons, and crowds out desirable grasses.
- It competes with desirable grasses for water, nutrients, and sunlight.
- Once it establishes, Summer grass is difficult to control.
Digitaria sp are a soil indicator of acid soil pH, and are a major problem for thin and weak sports fields and lawns.
How to Identify Summer Grass.
Digitaria sanguinalis is a summer annual weed grass, and has long, dark green narrow leaves and flat stems. These stems radiate out from the centre of the plant.
The stems of Summer Grass branch at the node, and form roots at these nodes. It has a membranous ligule and the sheaths at the leaf base have a light purple to white colour.
Germination of Summer Grass occurs when soil temperatures reach 12°C to 15°C at a 10 cm soil depth for 14 continuous hours. This weed emerges 2 to 3 weeks earlier than Crowsfoot.
In the Spring, wet and dry cycles result in the germination of Summer Grass. This occurs best when there is no shade and there is good soil moisture present.
The seeds of Summer Grass germinate from very early in the Spring to very late in the Autumn as long as adequate soil moisture exists. Plants that germinate in the Autumn tend to have a short life, and hard frosts, in for example Canberra, kill them.
You can see the seed heads of Summer Grass all through the Spring, Summer and Autumn. These are made up of several small, finger-like spikes, that radiate out from a central point, and are covered in tiny black seeds.
Digitaria sp spread from seed as well as stolons, and the seeds remain dormant in the soil for several years.
