Quick Facts

Quick facts

• Red Rice (Oryza rufipogon) is considered a weed of commercial rice crops.
• Its natural distribution covers much of Asia as well as northern Australia.
• Red Rice grows where there is stagnant or slow moving water up to a depth of 4 m.
• The geographical distance between wild population of Red Rice and cultivated commercial rice has meant this species is not an established problem in current Australian rice growing regions.

What Does It Look Like?

What is it?

Red Rice (Oryza rufipogon) is an aquatic grass that stands 1–5 m tall depending on the depth of the water it is growing in. It is tufted in appearance with a scrabbling or creeping appearance.

The green flower head is nodding and without glumes (small leaves at the base of the clusters of small flowers or spikelets) or with obscure glumes. This species is generally considered to be a perennial plant but can cross breed with commercial rice (Oryza sativa) creating an annual hybrid (Western Australian Herbarium 1998–; Clayton et al. 2006–; Bao-Rong Lu & Jackson undated; Scher undated).

For further information and assistance with identification of Red Rice contact the herbarium in your state or territory.

Flower colour

Green

Growth form (weed type/habit)

Aquatic

Where it currently grows? Preferred habitat

Red Rice prefers the same types of habitat as commercial rice. This includes most areas where there is stagnant or slow moving water such as natural swamps, pools, marshes and edges of lakes, as well as man made waterways like ditches, drains and rice fields. Red Rice prefers to grow in full sun and can be found it water up to 4 m deep. It is generally found on clay/loam or black soils and can tolerate acidic soils. In the Cape York area of Far North Queensland Red Rice forms grasslands with Oryza australiensis on the extensive alluvial coastal plains (Neldner et al. 1997; NAPPO 2003; Western Australian Herbarium 1998-; Bao-Rong Lu & Jackson undated).

Are there similar species?

The common names 'Red Rice' and 'Wild Rice' can be confusing as they are used for any weedy rice species. This includes commercial rice that has moved out of the cultivation situation and has returned to its red seed (grain) appearance (NAPPO 2003; The Office of the Gene Technology Regulator 2005).

Commercial rice and O. longistaminata are similar, and can be confused, with Red Rice, Red Rice is considered to be one of the parent plants of the rice grown commercial around the world. This close relationship means that Red Rice is hard to distinguish from the desired commercial rice growing in the field. Red Rice can also easily hybridize with commercial rice thus making identification even more problematic. Red Rice is best identified when in flower and producing seed; however, by this time it will have been competing with the desired commercial rice for space and resources for weeks (NAPPO 2003; The Office of the Gene Technology Regulator 2005: Scher undated).

Commercial rice has what are termed persistent flower clusters or spikelets, meaning the seed holding spikelets stay on the plant, whereas Red Rice has deciduous spikelets. The second species is O. longistaminata however this species only grows in Africa and has yet to be found in Australia (NAPPO 2003).

Why Is It A Weed?

What are its impacts?

Agriculture: Red Rice is considered a weed in commercial rice crops. Red Rice impacts on agriculture by contaminating and reducing the value of commercial harvested rice. While grains of Red Rice in harvested commercial white rice will not affect the taste of the product, in the eyes of the consumer they look like foreign particles and therefore reduce the monetary value of the product (NAPPO 2003; Scher undated).

The location of much of the Australian Rice Industry is further south than the natural distribution of Red Rice. Red Rice has not become a problematic weed in Australian rice growing areas yet. In northern Australia Red Rice is seen as a beneficial fodder crop and there is some concern in the Cape York region that additional agricultural pressure could have negative affects on Oryza grassland communities (Neldner et al. 1997; Cameron & Lemcke 1999; The Office of the Gene Technology Regulator 2005; AVH 2008).

How does it spread?

The seeds of Red Rice tend to fall near the parent plant; however, they can travel long distances through water and soil movement. Seeds can also be dispersed further by birds or as a contaminant in commercial rice seeds. Many rice species can also resprout vegetatively from subterranean nodes (sections of plant beneath the surface) after harvesting (NAPPO 2003; The Office of the Gene Technology Regulator 2005).

What is its history in Australia?

Red Rice is a native species in the northern parts of Australia (Neldner et al. 1997; Western Australian Herbarium 1998–; NAPPO 2003; AVH 2008).

How To Manage It?

Best practice management

Non-chemical control: Manual removal of Red Rice from rice paddies is very hard as it is almost impossible, prior to flowering and seeding, to distinguish Red Rice from the desired commercial rice. One control method is to plant commercial rice in rows and remove all rice seedlings that emerge and are deviating from the row pattern. Red Rice can best be controlled through prevention. This may involve the removal of all rice seedlings from nearby water sources and drainage that flows into the commercial rice bed. This will reduce the potential for Red Rice seeds to be transported by water or soil movement. A program of strategic planning and crop rotation with other grain or legume crops also allow for undesired rice seedlings to germinate in an environment where they can be identified and removed (NAPPO 2003).

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

The seeds of Red Rice cannot germinate in saturated soils; however, they are dormant at maturity and can remain dormant for three years waiting for the right germination conditions. Growth to maturity takes around 130 days, with the development of a mature seed head taking as little as 14 days (NAPPO 2003).

Where Is It Found?

Which states and territories is it found?

NT, QLD, WA

What areas within states and territories is it found?

In Australia Red Rice is found in the northern areas of Western Australia, Northern Territory and Queensland (Neldner et al. 1997; Western Australian Herbarium 1998-; Hussey & Lloyd 2002; NAPPO 2003; AVH 2008).

Where does it originate?

Red Rice is found in Australia, Bangladesh, China, India, Indonesia, Malaysia, Myanmar, Nepal, Papua New Guinea, Philippines, Sri Lanka, Thailand and Vietnam (Neldner et al. 1997; NAPPO 2003; Bao-Rong Lu & Jackson undated).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Oryza rufipogon

Other scientific names (synonyms)?

• Oryza fatua J.Koenig ex Trin.
• Oryza sativa var. fatua Prain

Does it have other known common name(s)?

Wild Rice, Arrozrana, Jingirra, Brownbeard Rice