Sugarcane pests and weeds

Downy mildew

Causal agents: Peronosclerospora philippinensis and P. sacchari

• Can cause significant yield losses, with losses of up to 40% reported overseas.

Symptoms

• Cream-white leaf stripes that redden with age.
• Stunting of infested stools.
• Down may be seen on the underside of infested leaves, especially under humid conditions.
• Leaves may become shredded at cooler times of the year.

Spread

• Spread with infected planting material.
• Wind-borne spores for short distance dispersal, due to short lifespan of spores.

More information

Grassy shoot disease

Causal agent: Sugarcane grassy shoot phytoplasma

• Can cause significant yield losses, with some milling areas in Vietnam suffering 50% reductions in yield due to the disease.

Symptoms

• Excessive tillering that fails to develop into mature stalks.
• Yellow chlorotic shoots.
• Shoots may not develop after harvest causing a very patchy ratoon crop.

Spread

• Infected planting material.
• May be spread by insects.

Leaf scorch

Causal agent: Stagonospora sacchari

• Can cause significant yield losses of up to 30% overseas.

Symptoms

• 50-200 mm long, 5-10 mm wide spindle (cigar) shaped leaf lesions with dead tissue in the centre.
• Favoured by rain and warm conditions.

Spread

• Spores are spread by wind and wind-blown rain.

Mosaic viruses

Causal agent: Sugarcane streak mosaic, Sorghum mosaic and Sugarcane mosaic viruses

• Can cause significant yield loss.

Symptoms

• Irregular mottled green pattern on leaves.
• Symptoms are more easily seen in young leaves, and tend to fade as the leaves age.

Spread

• Infected planting material.
• Transmitted by aphids that feed on infected plants.
• Knives used on infected plants may also spread the disease.

Ramu stunt

Causal agent: Unknown Tenuivirus

• Plant death and failure of ratoon crops occurs in susceptible varieties.

Symptoms

• Stunting of individual shoots or whole stools.
• Leaves develop small cream-green flecks, which grow to become 2-5 mm long yellow-green streaks.

Spread

• Vectored by the island sugarcane leafhopper (Eumetopina flavipes), which is not present in sugarcane-producing areas of Australia.
• Propagation material can also spread the disease.

More information

White leaf disease

Causal agent: Sugarcane white leaf phytoplasma

• Can cause reduced yields and sugar content. Losses of up to 100% have been reported overseas in susceptible varieties.

Symptoms

• Leaves develop cream-white coloured stripes parallel to the midrib, which eventually cover the whole leaf.
• Infected leaves are narrower than healthy leaves.
• Plants tiller profusely, have short internode length and look bushy.
• Poor ratooning after harvest, which results in patchy crops.

Spread

• Transmitted by the exotic leafhoppers Matsumuratettix hiroglyphicus and Yamatotettix flavovittatus .
• Infected propagation material can also spread the disease.

Exotic borers

Chilo auricilius, C. infuscatellus, C. sacchariphagus, C. terrenellus and C. tumidicostalis: Eldana saccharina, Polyocha depressella, Scirpophaga excerptalis and Sesamia grisescens

• Significant yield loss including total crop destruction can occur. Damage depends on the borer species and cane variety grown.
• Most severe losses occur with:
  – Top borer (Scirpophaga excerptalis)
  – Ramu shoot borer (Sesamia grisescens)
  – Stalk borer (Chilo sacchariphagus)
  – Stalk borer (Chilo terrenellus)

Description and symptoms

• Adults are medium sized grey or white moths.
• Larvae create tunnels in the stem.
• Feeding may cause damage to the growing point and causes the formation of dead heart in young plants.
• Small holes may be visible on infested stalks.

Spread

• Adult moths are able to fly over short distances.
• Larvae can be spread inside infested planting material.

Sugarcane planthoppers

Perkinsiella vastatrix and P. vitiensis

• In exceptional circumstances high populations can reduce yield and sugar content.
• Perkinsiella vastatrix and P. vitiensis can act as vectors of Fiji leaf gall.

Description and symptoms

• Similar to the sugarcane planthopper (Perkinsiella saccharicida) in size and appearance, being a 4-6 mm long, brown coloured, leafhopper.
• Copious excretion of honeydew may cause development of sooty mould.

Spread

• Insects can fly many kilometres.
• Insects and eggs can be carried on sugar-cane stalks and leaves.

Sugarcane pyrilla

Pyrilla perpusilla

• Feeding causes yield losses and reduced sugar content.

Description and symptoms

• Adults are 10 mm long and 2-4 mm wide, light yellow-brown colour.
• Feeding causes yellow spots on their leaves, especially around the midrib on the underside of the leaf.

Spread

• Plant material can potentially spread the pest between areas.

Sugarcane whitefly

Aleurolobus barodensis

• Can cause significant yield loss.
• Severe infestations may result in yield reduction of up to 65%.

Description and symptoms

• Nymphs are oval shaped white to grey in colour and feed in groups on the leaves.
• Adults are winged, dull white and 1-3 mm in body length.
• Feeding causes leaves to appear pale.
• The excretion of honeydew may support the growth of sooty mould.

Spread

• Movement of infested plant material.

Sugarcane woolly aphid

Ceratovacuna lanigera

• Significant yield loss can occur, with losses of up to 30% reported overseas.

Description and symptoms

• Small (2 mm long) white coloured aphids that have a woolly appearance.
• Copious excretion of honeydew may cause development of sooty mould.

Spread

• Spreads with the movement of infested plant material.
• Potentially wind dispersed.

Fiji leaf gall

Causal agent: Fiji disease virus

• Significant or complete yield losses in susceptible varieties.

Symptoms

• Green or white galls between 1-200 mm long, 1-4 mm wide and 1-2 mm high form on the underside of the leaf blade and midrib.
• Leaves at the top of the plant look ragged.
• Causes stunting, profuse tillering and plant death.

Spread

• Reported from NSW north to Nambour. Has occurred from Maryborough to Mackay in Queensland, but has not been reported in these districts for many years. Has never been recorded in the districts north of Bowen.
• The sugarcane planthopper (Perkinsiella saccharicida) spreads the disease between plants.
• Infected planting material also spreads the disease.

Management

• Use resistant varieties.
• Use disease free planting material.

Fiji leaf gall fact sheet

Leaf scald

Causal agent: Xanthomonas albilineans

• Significant yield losses can occur. Complete crop losses can occur in highly susceptible varieties.

Symptoms

• Chlorotic (white) stripes and patches on leaves.
• White pencil-line visible along the middle of the white leaf stipes.
• When stalks are sliced, the vascular bundles are red in the nodes.
• Side-shooting from the base of the plant.
• Causes poor ratooning and stalk death in susceptible varieties.

Spread

• Present in all sugarcane growing regions in Australia.
• Infected planting material.
• Contaminated cutting implements including knives, harvesters, whole stalk and billet planters.
• Wind-blown rain.

Management

• Use disease free planting material.
• Grow resistant varieties.
• Disinfect planting material.

Pachymetra root rot

Causal agent: Pachymetra chaunorhiza

• Significant yield losses of up to 40% have been reported in susceptible varieties.

Symptoms

• Larger roots exhibit a soft flaccid rot.
• Infection may cause excessive stool tipping and loss of plants at harvest and poor ratooning.

Spread

• Widespread in Northern, Herbert, Central Queensland districts and Condong mill area in NSW.
• There is limited distribution in Burdekin and other NSW cane growing areas.
• It is spread in soil carried on machinery or attached to stalks of cane.

Management

• Strategic planting of resistant varieties.
• No fungicides are effective against Pachymetra at economical rates.

Fact sheet

Ratoon stunting disease

Causal agent: Leifsonia xyli subspecies xyli

• Average yield loss of 15-20% can occur, with up to 60% loss if conditions are favourable for the disease.

Symptoms

• Visible stunting, causing an uneven appearance in the cane fields.
• Red-orange dots are often visible in the nodal tissue, visible when stalks are sliced in half.

Spread

• Found in all sugar growing districts of eastern Australia.
• Spread by planting infected cuttings and use of contaminated cutting implements.

Management

• Plant approved disease free seed.
• Destroy all volunteer cane.
• Disinfecting planting and harvesting equipment.

Fact sheet

Sugarcane mosaic virus

Causal agent: Sugarcane mosaic virus (Strain A)

• Significant yield losses of 20-30% in susceptible varieties.

Symptoms

• Mottled pattern on leaves with light green to yellow and dark green patches.

Spread

• Has been reported from all regions. Currently restricted to the Bundaberg and Childers districts.
• Transmitted by aphids and infected planting material.

Management

• Resistant varieties and use of disease free planting material.
• If infected plants are found, destroy them immediately to reduce spread.
• Manage weed hosts of the vectors.

Sugarcane smut

Causal agent: Sporisorium scitamineum

• Yield losses of 30-100% have been reported.

Symptoms

• A black whip-like structure develops from the growing point of the sugarcane plant.
• Severe stunting, thin grassy stalks and death of plants.

Spread

• Found in all sugar growing districts of Australia.
• Wind dispersed.
• Spread by planting infected cane cuttings.
• Can be spread on machinery, shoes etc.

Management

• Resistant varieties.
• Hot water treatment can be used to eliminate smut from infected planting material but treated plants can be reinfected after planting.
• Fungicides such as, Sinker® (a.i. Flutriafol) can protect plants from reinfection for several months and is approved for use against sugarcane smut.

Fact sheets and information

Sugarcane striate mosaic virus

Causal agent: Sugarcane striate mosaic-associated virus

• Significant yield losses of up to 100% can occur due to stunting and plant death in susceptible varieties.
• Failure of ratoon crops.

Symptoms

• Short, fine (0.5 mm wide by 0.5-2 mm long), light green striations on leaves.
• Symptoms first appear on the young leaves.
• Susceptible plants become stunted and die.

Spread

• Found in the Burdekin district.
• Sett and soil-transmitted.
• Spread by contaminated machinery and soil on feral animals such as pigs.

Management

• Resistant varieties.
• Disease-free seed cane.
• Clean machinery.
• Feral animal control.

Sugarcane weevil borer

Rhabdoscelus obscurus

• Reduced sugar content with losses of up to 2 CCS units reported.

Description and symptoms

• Adults are dark coloured 12-15 mm long, with a long snout.
• Eggs are laid into cavities chewed in the stalk or into damaged cane.
• Larvae feed inside the internodes of the stalk (often only in the lowest ones) and fill the stalk with frass (waste).

Spread

• Found in districts from Plane Creek (near Mackay) to Mossman.
• Spread by infested planting material and adult weevils that can fly.

Management

• Managing harvest residues.
• Reduce stalk damage and lodging as damaged cane attracts the pest.
• Resistant varieties.
• Insecticides.

Giant sensitive plant

Mimosa diplotricha

Description

• Shrub to sprawling vine 2-3 m tall, with 4 angled stems with small prickles along the stems.
• Bright green, 10-20 cm long fern-like leaves that close up when touched and at night.
• Flowers are 12 mm wide, pale pink coloured, fluffy balls.

Spread

• Seeds are transported by water, vehicles, machinery, on the coats of livestock and feral animals, and contaminated soil.
• Found in Far North Queensland around Mackay and from Ingham to Cooktown.

Itch grass

Rottboellia cochinchinensis

Description

• Large, 3 m tall grass with blue-green coloured leaves.
• Leaves and stems covered in stiff irritating hairs.

Spread

• Seeds are transported by water, vehicles, machinery, on the coats of livestock and feral animals, and contaminated soil.
• Occurs in coastal areas from the NSW-Queensland border to North Queensland. Also present in the Northern Territory.

Fact sheet

Olive hymenachne

Hymenachne amplexicaulis

Description

• A perennial grass that can grow 2.5 m tall.
• Stems are erect and contain white pith.
• Leaf blades are 10-45 cm long and up to 3 cm wide. The base of the leaf curls around the stem.
• Flowers are spike-like and 20-40 cm long.
• It is capable of growing in permanent wetlands.
• Listed as a weed of national significance

Spread

• Grows from seed and broken stem fragments.
• Seeds are spread by water movement and birds.
• Found in Cape York in Queensland to Casino in NSW.

Red witchweed

Striga asiatica

Description

• A parasitic weed that grows attached to the roots of a host plant.
• It grows 10-40 cm tall, with leaves arranged in opposite pairs along the stem.
• The flowers are usually red, but can be white, yellow or pink.

Spread

• The seeds are dust like and can drop into the soil easily, enabling it to spread.
• Wind dispersal, soil movement, or via animals and people.
• Eradication process is ongoing in the Mackay region.

Siam weed

Chromolaena odorata

Description

• A dense tangling bush that can grow up to 2-3 m tall. The root system is fibrous and shallow in most soils.
• Leaves are green, hairy, soft and triangular.
• The plant produces masses of pale lilac flowers from May to July and again in September to October.

Spread

• Windborne seeds spread the weed.
• Carried on vehicles, clothing, footwear and animals.
• Found in North Queensland.

Sicklepod

Senna obtusifolia

Description

• Woody shrubs to 2 m in height.
• Small yellow flowers.
• Leaves are made up of 2-3 pairs of leaflets, each leaflet is around 4 cm long.
• Long thin sickle shaped seed pods up to 18 cm long.

Spread

• Seeds spread with water, harvested sugarcane or mud on machinery.
• Seeds can also be spread by livestock and feral animals.
• Found in Darwin and surrounding areas of the NT. In Queensland around Mackay, Ingham and parts of the Atherton Tablelands.

Fact sheet

Singapore daisy

Sphagneticola trilobata

Description

• Ground cover with glossy green leaves.
• Yellow to orange-yellow daisy flowers 2 cm in size.
• Flowers all year.

Spread

• The plant is capable of regrowth from cuttings.
• It is spread primarily by cuttings that are created when slashing and pruning.
• Found along the east coast of Queensland.