Summer Grass (Digitaria sanguinalis).

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.

 

 

 

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.

 

 

 

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.

 

 

Digitaria sp spread from seed as well as stolons, and the seeds remain dormant in the soil for several years.

 

Summary.

Classification: Monocot.

Photosynthetic Pathway: Summer Grass is a C4 weed.

Height: Digitaria sanguinalis grows up to 30 cm in height.

Leaf Length: The leaves of Summer Grass are 5 to 15 cm long.

Comments: Coarse hairs cover the leaves.

Habitat: Summer Grass (Digitaria sanguinalis) has poor drought tolerance and grows in full sun and in shade. Its natural habitat is in sandy or sandy loam soils.

However, you often find Crabgrass next to driveways or pathways, and once it establishes it is tolerant of hot, dry, and compact soils.

 

 

 

You can use both cultural control methods and Summer Grass herbicides to control Digitaria sanguinalis in your lawn and turf grass.

 

 

 

• You can remove Summer Grass by hand but it will come back if the turf cover is thin or there are bare patches.
• It’s important to properly feed your turf with the right turf fertilizer, and if possible raise the right height of cut.
• US work shows that if you mow couch at 50 mm vs 25 mm, you get a 10% decrease in Crabgrass.
• Correct nutrition encourages turf grass to spread and outcompete Summer Grass.

 

The key to manage Digitaria sanguinalis is to stop seed production. Even though selective post-emergent Summer Grass herbicides are available, your best option is to use a pre-emergent herbicide.

 

Summer Grass Germination.

Digitaria sanguinalis germinates in the Spring when soil temperatures reach 13°C or there is an air temperature of 18°C for four or more days. Once the soil temperature reaches 13°C, Crabgrass germinates over the next 2 to 3 months.

Management Timeline for Summer Grass.

 

Pre-emergent Control of Summer Grass.

Pre-emergent herbicides for Summer Grass include granular pre-emergents like:

• Onset 10GR.
• Echelon.
• Echelon Duo and
• BASF Freehand.

 

Liquid options for Summer Grass include:

• Barricade.
• Pennmag.
• Dimension.
• Envu Specticle and
• Battalia 435.

• All of the above will prevent Summer Grass seed from establishing.
• Use these at the correct rate and with the right timing to get the best results.
• Do not apply any of these pre-emergent herbicides if you plan to seed within several weeks after application, as these herbicides will kill turf grass seedlings.
• Apply pre-emergents before Summer Grass germinates, and when soil temperatures are at 13°C for several consecutive days. Dimension Herbicide also gives post-emergent control up to the 1-tiller stage.
• Depending on where you are, split applications at half the high label rate, almost always improve Summer Grass control in comparison to a single application at the high use rate.
• Aim to make the second application 4 to 6 weeks after Summer Grass germinates.

 

Initial Pre-emergent Application.

• Make an Initial application before any Digitaria sp germinates.
• Pre-emergents prevent germinating Summer Grass seedlings from developing, so apply these before any it germinates.

 

Split Pre-emergent Application.

• Make split applications 6-8 weeks after the initial application.
• A second application extends the residual control of Summer Grass, and also increases Crowsfoot control.
• This approach is especially effective on sandy soils with low organic matter.

 

Post or Pre-emergent + Post emergent Tank Mixes.

• Apply post-emergents or a pre-emergent herbicide with a post-emergent to control germinated Summer Grass.
• You get the best results on germinated Digitaria sp with post emergents, if you apply them to small 1 to 3 leaf Summer Grass.

 

Post-Emergent Control of Summer Grass.

• With post-emergents, if the Summer Grass has tillers you need two applications, 2 or 3 weeks apart.
• You get the best results on small plants that have yet to tiller, and if you get uniform coverage. Thus, apply these only when plants are visible in the stand.
• Be aware that injury is likely to occur if you use these products when temperatures are greater than 29°C.
• Dithiopyr (Dimension) is another option for post-emergent Summer grass control in warm and cool season turf. Turf grass managers mainly use Dimension for pre-emergent control, but applications in the Spring do provide early post emergent control. You must apply Dimension to seedling Summer Grass for best results.
• Applications to Summer grass that already has tillers, gives variable post-emergent control in the early Summer. Aim to irrigate within 24 hours to reduce losses through volatilisation in late the Spring or Summer.

 

For post emergent control of Summer Grass options include:

• ProForce Geronimo (MSMA).
• Quinstar (Quinclorac). For the best results use Voltage MSO adjuvant. Control is inconsistent when you apply this at the 2- to 4-tiller growth stage, and larger plants need sequential applications to get good control.
• Pylex is registered in the US. It is important to add a methylated seed oil (MSO) in the tank with Pylex. Pylex bleaches Summer Grass leaves for 7 to 14 days after application before the plants die.

 

Non Selective Control of Summer Grass.

• Glufosinate-ammonium provides Crabgrass control for 4 to 6 weeks, but it regrows and recovers due to the limited movement of glufosinate.
• Glyphosate. You can use Glyphosate to control Summer Grass but if water quality is an issue then use ProForce Manta Ray.

 

The following are non-selective but also have a long term residual and stop re-growth of Summer Grass.

• Renegade. Renegade stops germination for up to 12 months, and reduces the need for multiple herbicide applications.
• Numchuk Quad. This gives effective post and pre emergent Crabgrass control for up to 12 months.
• Cortex Duo. Cortex Duo gives a rapid knockdown of Summer Grass, and residual control for up to 3 months. It is also safe to use around trees.

 

Table of Non Selective Herbicides for Summer Grass Control.