Hairy Bittercress (Cardamine hirsuta).

Hairy Bittercress is also called Swinecress and Flick Weed. It is a Winter annual broadleaf weed and is a member of the mustard family.

For more information, please check out our weed ID chart.

This weed is a good indicator of poorly drained, wet soils. It is often is found in disturbed areas.

 After you read this, you will be able to:

• Identify Swinecress and Flick Weed.
• Know its habitat.
• Know the best cultural and chemical options to control it.

Why is Bittercress a Weed?

• This weed produces a large number of seeds.
• The seeds germinate immediately or stay dormant for several years.
• The seeds are sticky so disperse easily.
• In a moist environment like the Southern Highlands of NSW, this weed germinates, and grows at any time of the year.
• It is a host plant for aphids.

This weed is typically one of the first weeds to appear in the Spring. However, it can grow all the year-round when suitable conditions exist.

The distribution map is courtesy of The Living Atlas of Australia.

Bittercress Identification.

Flick Weed is a weed in the ACT, NSW, NT, QLD, SA, TAS, VIC, and WA.

Category: It is a broadleaf (Dicot) weed.

Photosynthetic Pathway: This weed is a C3 Weed.

Flower: The white flowers are tiny with four white petals. They are around 3 mm long.

Height: It is a Slender annual herb that grows to a height of 35 cm.

Leaves: Flick Weed has thin, sparsely hairy leaves that form a rosette at the base. These leaves have 1 to 7 leaflets. The side leaflets are circular and the terminal leaflets have a kidney shape. On both sides of the leaves are numerous tiny hairs.

Reproduction:

• Bittercress forms lime green seed pods up to 25 mm long.
• These flick the seeds out when they are ripe. The seeds can travel 1 to 2 metres from the plant.
• Each plant produces up to 5,000 seeds.
• These can germinate immediately.
• However, if conditions they can survive for several years.

Comments: The seeds tend to germinate in the Autumn or Winter. They stay dormant in cold weather. In the Spring they resume their growth, and then produce more seeds. It has a 12-week lifecycle.

Habitat: This weed inhabits most gardens and thin lawns. It is common in damp, sunny or disturbed soils.

• Prevention is the best way to manage this weed.
• Hand weeding is very effective to manage small populations. However, you must repeat this regularly.
• It is also important to hand weed before it flowers. This is because the seeds will still disperse when you handle the plants.
• Once you pull it up, remove the plant from the area and dispose of it.
• The seeds tend to not germinate where there is competition or shade i.e. dense turf grass. This means that turf grass selection  for your site is important.
• Proper fertilising, mowing, and watering will encourage turf growth. This also reduces the chances of weed establishment.
• If you frequently mow in the Spring, this removes the flowers before any seeds develop.
• However, as this weed grows from a rosette, it tends to tolerate mowing.

• Currently only BASF Freehand and Pendimethalin (ProForce Battalia 435 Herbicide) have a label for this weed in Australia.
• In the US, pre-emergents include: Dimethenamid-P + Pendimethalin, Indaziflam, Oxadiazon, and Dithiopyr.

Post Emergents for Bittercress.

Post emergents include:

• 2,4-D.
• Warhead Trio. Safe on Buffalo grass.
• Contra M herbicide. Do not use Contra M on Buffalo grass.
• MCPA.
• Weed Blast MA. Safe on Buffalo grass.
• Dicamba. Don’t use Dicamba on Buffalo grass..
• Quali-Pro Negate.

Non Selective Control of Bittercress.

• Glufosinate-ammonium provides control for 4 to 6 weeks. However this weed will regrow after you treat it.
• Glyphosate. You can use Glyphosate. If water quality is an issue then use ProForce Manta Ray.

The list below is of non-selective with a long term residual. This stops re-growth of this weed.

• Renegade. Renegade stops seed germination for up to 12 months. It reduces the need for herbicide applications.
• Numchuk Quad. This gives effective post and pre emergent Flick Weed control for up to 12 months.
• Cortex Duo. Cortex Duo gives a rapid knockdown. It then has a 3 month residual. It is also safe to use near trees.