Weedbusters

Working together to protect New Zealand

  • Home
  • Weedbusters
    • Who are Weedbusters?
  • What Are Weeds?
    • Weed List
    • Controlling Weeds
    • Disposing of Weed Waste
    • Banned Plants
  • Get Involved
    • Become a Weedbuster
    • Weedbusters Near You
    • Weed Quiz
  • Resources
    • How to…
    • Weedbusting Guide
    • Plant Me Instead Booklet
    • Using Weedbuster photographs
    • Useful Links
  • Contact Us
You Are Here:
  1. Home
  2. What Are Weeds?
  3. Weed List
  4. Manchurian rice grass
What Are Weeds?

Weed Information Sheet

  • Weed List
  • Controlling Weeds
    • Controlling Pest Shrubs & Trees
    • Controlling Pest Vines
    • Controlling Pest Herbs & Ground Covers
    • Controlling Pest Grasses
    • Controlling Pest Aquatic Weeds
  • Disposing of Weed Waste
  • Banned Plants

Popular Links

  • Weed List
  • Weed Quiz
  • Weedbusters Near You

Browse weeds by alphabet

a b c d e f g h i j k l m n o p q r s t u v w x y z

Manchurian rice grass

Botanical Name

Zizania latifolia

Family

Poaceae (grass)

Also known as

Manchurian wild rice

Where is it originally from?

China

What does it look like?

Dense, mat-forming perennial (<2-3 m) with rhizomes (2-3cm diameter) up to 5 m long and fibrous roots. Harsh, papery, dull grey-green leaves (2-3 cm wide) are straight, up to 2.5 m long, have a stout midrib, taper to a point, and rustle loudly in the wind. From November to December a purplish or red-brown flowerhead (40-60 cm long) is produced.

Are there any similar species?

Raupo is similar, but has 1-2 m leaves that are thick and spongy, 2 cm wide, have no midrib, and twist upwards, it has a bullrush-style seedhead. Flax leaves are much wider, smoother, thicker and shinier than Z. latifolia and have a balsa-like flowering stalk.

Why is it weedy?

Seeds and rhizomes fragments spread rapidly and widely in wet or dry areas, and it forms dense, long-lived stands on land and water margins, overtopping other riparian species. Extremely tolerant of damage, grazing, cold or heat, wind, fire, different soil types, moderate shade and moderate salinity.

How does it spread?

Rhizomes spread outwards slowly, but more rapid spread comes from seeds and rhizome fragments being moved by water, livestock, machinery, clothing, and possibly by birds. Road graders, soil movement, dumped vegetation, contaminated diggers, farm machinery, eel nets, boats and trailers all spread seed and rhizome fragments into new catchments, lowland pasture, roadsides, water tables, drains and farm dams.

What damage does it do?

Forms permanent stands in water margins and dry land of nothing but Zizania latifolia, replacing all other species. Causes silt to accumulate, altering water systems, causing flooding and destroying habitat for aquatic fauna and flora.

Which habitats is it likely to invade?

All fresh or moderate-saline waterbodies and margins, wetlands, damp ground and fernland.

What can I do to get rid of it?

Always begin control work at the top of the catchment. Resource consent is required for spraying Haloxyfop herbicides over water - contact your regional council for more information on this.
1. Dig out only very small sites. Dispose of rhizomes and seedheads at a refuse transfer station, or burn them.
2. Spray: 520g/L haloxyfop-P-methyl (4ml/L + 5ml/L seed oil adjuvant) or 98.6g/L haloxyfop-P-methyl (20ml/L + 5ml/L seed oil adjuvant). Initial spray September-April. Follow up 6-8 monthly (not in winter) before regrowth reaches 1m, to prevent rhizome recovery.

CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and directions for the purchase, use and storage of the product, are followed and adhered to.

What can I do to stop it coming back?

Rhizomes persist for years and can recover after spraying, and seed bank may reinfest bared areas, so ongoing control is important. To prevent problems with rhizome disposal, it is better to kill rice grass standing using an overall spray application: budget for 50-70% regrowth after first 1-2 treatments, 10% thereafter. Usually need 5-10 treatments over 6-8 years for eradication.

Images

Photo: Carolyn Lewis
Photo: Carolyn Lewis
Photo: Trevor James
Photo: Carolyn Lewis
Photo: Carolyn Lewis
Photo: Trevor James
Photo: Trevor James
Photo: Trevor James
Photo: Carolyn Lewis
Photo: Trevor James
Photo: Trevor James
Photo: Trevor James

Download PDF Information Sheet

Browse/Search Weeds

Weedbusters

  • Who are Weedbusters?

What Are Weeds?

  • Weed List
  • Controlling Weeds
  • Disposing of Weed Waste
  • Banned Plants

Get Involved

  • Become a Weedbuster
  • Weedbusters Near You
  • Weed Quiz

Resources

  • How to…
  • Weedbusting Guide
  • Plant Me Instead Booklet
  • Using Weedbuster photographs
  • Useful Links

Contact Us

  • Home
  • Contact Us

© 2025 Weedbusters • Website by RS

  • Home
  • Weedbusters
    • Who are Weedbusters?
  • What Are Weeds?
    • Weed List
    • Controlling Weeds
      • Controlling Pest Shrubs & Trees
      • Controlling Pest Vines
      • Controlling Pest Herbs & Ground Covers
      • Controlling Pest Grasses
      • Controlling Pest Aquatic Weeds
    • Disposing of Weed Waste
    • Banned Plants
  • Get Involved
    • Become a Weedbuster
    • Weedbusters Near You
    • Weed Quiz
  • Resources
    • How to…
      • Raise Weeds Awareness
      • Organise a Weedbusters Event
    • Weedbusting Guide
    • Plant Me Instead Booklet
    • Using Weedbuster photographs
    • Useful Links
  • Contact Us
  • Find us on Facebook