Silk forage sorghum (Sorghum species hybrid cultivar "Silk")

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Silk forage sorghum is a vigorous summer plant. It can pose a risk to commercial crops and fodder.

Profile

How does this weed affect you?

It has potential to harbour disease and insect pests of, and outcross with annual grain and forage sorghums.

What does it look like?

Silk forage sorghum is a vigorous, rather coarse short lived summer plant. It forms tussocks up to 4 m high.

References

Parsons W.T. and Cuthbertson E.G. (1992) Noxious weeds of Australia. (Inkata Press, Melbourne).

Control

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.

Flupropanate 745 g/L (Various products)
Rate: 200 mL per 15 L of water
Comments: Knapsack spray when plants are actively growing and at least 30 cm tall. Spray to the point of run-off. Follow label directions as per Johnson grass.
Withholding period: Spot spray: Do NOT graze or cut for stock feed for at least 14 days. Blanket spray: Do NOT graze, or cut for stock feed for at least 4 months. If stock are grazed in treated areas after required time has passed, remove stock from treated areas and do NOT slaughter or milk for human consumption until they have been on clean feed for at least 14 days.
Herbicide group: 15 (previously group J), Inhibition of very long chain fatty acid synthesis (VLCFA inhibitors)
Resistance risk: Moderate

Flupropanate 745 g/L (Various products)
Rate: 12 L/ha
Comments: Boom spray. Follow label directions as per Johnson grass.
Withholding period: Spot spray: Do NOT graze or cut for stock feed for at least 14 days. Blanket spray: Do NOT graze, or cut for stock feed for at least 4 months. If stock are grazed in treated areas after required time has passed, remove stock from treated areas and do NOT slaughter or milk for human consumption until they have been on clean feed for at least 14 days.
Herbicide group: 15 (previously group J), Inhibition of very long chain fatty acid synthesis (VLCFA inhibitors)
Resistance risk: Moderate

Flupropanate 745 g/L (Various products)
Rate: 1 L per 100 L of water.
Comments: High volume spray to actively growing plants at least 30 cm tall. Spray to the point of run-off. Follow label directions as per Johnson grass.
Withholding period: Spot spray: Do NOT graze or cut for stock feed for at least 14 days. Blanket spray: Do NOT graze, or cut for stock feed for at least 4 months. If stock are grazed in treated areas after required time has passed, remove stock from treated areas and do NOT slaughter or milk for human consumption until they have been on clean feed for at least 14 days.
Herbicide group: 15 (previously group J), Inhibition of very long chain fatty acid synthesis (VLCFA inhibitors)
Resistance risk: Moderate

Glyphosate 360 g/L (Various products)
Rate: 150 mL in 15 L of water.
Comments: Spot spray actively growing plants at the early head stage. Follow label directions as per Johnson grass.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

Glyphosate 360 g/L (Various products)
Rate: 6.0 L per Ha
Comments: Boom spray actively growing plants at early head stage. Follow label directions as per Johnson grass.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

Glyphosate 360 g/L (Various products)
Rate: 1.0 L per 2.0 L of water
Comments: Wiper control. Follow label directions as per Johnson grass.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

Biosecurity duty

The content provided here is for information purposes only and is taken from the NSW Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.

For technical advice and assistance with identification please contact your local council weeds officer.

Reviewed 2025