The maize variety characteristics table contains information about hybrid susceptibility/resistance to diseases.

See Maize variety characteristics table

On this page:

• Rots
• Wallaby ear
• Blights
• Smuts
• Viruses
• Rusts

Rot diseases in maize

Rots in maize can be caused by a wide range of fungal pathogens.

Some of the more common are:

Fusarium stalk rot and Fusarium kernel rot (Fusarium moniliforme) (Fusarium verticilliodes)

Fusarium is common on the Atherton Tablelands particularly in the first maize crop after a lengthy pasture phase. It can also occur as seedling blight but this is not common due to improved seed management.

Seedlings have poor root development and growth and may be pale green or purple colour. There is often a poor seedling stand. Mature plants show pink coloured, rotted internal stalk tissues. The pink colour may also be seen on stalk nodes. Stalks are weak and lodge easily.  As well as the stalk rot, the kernels may also become infected.

Use resistant hybrids to combat this disease.

Gibberella stalk rot (Gibberellazeae)

Very common on the Atherton Tablelands, especially in the wetter parts, where it can cause serious yield loss. The disease is much less serious in southern Queensland. It occurs in wet weather and where there is plant stress during grain fill. It is common where maize monoculture is practised. Plants die prematurely.

The stalk rots, showing internal tissues that are shredded and discoloured (may be pink or quite red). Stalk surfaces show a reddish brown discolouration, particularly around the nodes. Affected stalks are weak and break easily. Later in the season small, round, bluish-black fruiting bodies may be found around the nodes of dead stalks.

Use crop rotation and/or resistant maize hybrids to combat this disease.

Gibberella ear rot or pink ear rot (Gibberellazeae)

A disease of tropical and subtropical regions, especially wetter areas. Particularly significant on wetter parts of the Atherton Tablelands. Apart from causing yield loss it can produce a toxin (zearalenone), which is harmful to livestock, especially pigs. Infection is favoured by wet weather, maize monoculture or plant stress during grain fill.

A reddish-pink or whitish-pink fungal growth from the tip of the ear to the base is usual, although infection can occur whenever damage occurs in the ear. Husks tend to bind to the kernels and there may be black fruiting bodies on external husk leaves. Infection is transmitted through windborne spores.

Choose resistant hybrids and control weeds to reduce humidity in the crop canopy (high humidity promotes infection).

This disease has occurred on the Darling Downs in some seasons, especially when summer rainfall has been below average.

There is little information available on the relative susceptibility of different hybrids to this disease. Husk cover and pendulous ears reduce the incidence of this disease.

Losses due to ear rots can also be reduced by prompt harvesting, even if moisture levels are slightly higher and drying is necessary.

See Gibberella ear rot disease photo.

Wallaby ear in maize

The physiological condition known as wallaby ear is caused by toxin injected by the leafhopper (Cicadulina bimaculata) while feeding. The condition is more common in subtropical coastal areas where it can have a serious effect on yield. Leaves of affected plants are dark green or blue-green in colour. They are short and held at a very upright angle, and veins on the lower leaf surface are thickened. Use tolerant hybrids and control leafhoppers with registered insecticides when plants are young.

See Wallaby ear disease photo.

Blight in maize

Leaf blight

Turcica/turcicum leaf blight or northern leaf blight (Exserohilum turcircum) can be found in all regions and may be serious in susceptible hybrids. Warm wet weather favours infection and disease development.

Leaves show long, spindle-shaped, greyish-green, water-soaked spots (up to 150 mm x 20 mm), which turn light purplish-brown or grey. In favourable conditions the spots may join, blighting almost the entire leaf. The fungus survives on volunteers and residues and is spread by wind and rain.

Choose resistant hybrids and avoid sequential plantings (stops disease build-up) as chemical control is usually not economic.

See Turcica leaf blight photo.

Maydis leaf blight (Southern leaf blight (Bipolarismaydis))

Frequently a problem of tropical humid areas. Infection and disease development is favoured by warm, showery, humid weather.

Leaves show small, oval, pale brown-tan spots (10-40 mm x 5 mm), with a dark border and sometimes surrounded by a pale yellow halo (spots tend to be smaller than those of Turcica leaf blight). This disease may also cause a dark rot of the seeds, beginning at the tip. The fungus survives on diseased residues, volunteer maize and grasses, and may be carried over in the seed.

Plant resistant hybrids to combat this disease.

See Maydis leaf blight photo.

Smut in maize 

Smuts are not as common as rusts, and usually attack the plant's reproductive components rather than the leaves or stems.

Boil smut (Ustilago saydis) attacks any above-ground growing part of the plant to form blisters or galls containing black spores.  Mature galls can grow as large as 20 cm in diameter. Spores can be spread by wind, seed, clothes or farm machinery, and can survive in the soil for many years. Ensure good hygiene and treat seed with registered fungicide.

Head smut (Sphacelotheca reiliana) infects the young seedling, then grows through the plant, replacing reproductive tissues (ears and/or tassels) with masses of spores. Distortion is common, and leafy structures may replace the plant's flowering components. The fungus survives in the soil, and may also be seed-borne. Cool weather and dry seedbed conditions favour this disease. Plant resistant varieties, or avoid early planting of susceptible varieties.

See Head smut photo.

Viruses in maize

Dwarf mosaic virus of maize

Maize dwarf mosaic (Johnson grass mosaic virus) is a disease of temperate and subtropical areas. It can be a serious problem in south Queensland. Many maize hybrids have good resistance but sweetcorn varieties, especially supersweet types, are highly susceptible if planted late in the season.

Light and dark green patches form on the leaves, showing a mosaic effect. They can also develop in ring-spot patterns. Severely affected plants can be completely yellow, reduced in size and suffer considerable yield reduction. The disease is spread by aphids and uses Johnson grass and standover or regrowth of forage and grain sorghum crops as hosts between seasons.

Planting resistant cultivars is the primary management method for this disease. Also control Johnson grass infestations.  Once plants are infected, there is no cure.

See Dwarf Mosaic virus photo.

Rust in maize

Common rust (Puccinia sorghi) is commonly found in temperate and sub-tropical regions. Usually only found on lower leaves of resistant hybrids. Tends to be more serious on sweetcorn. Cool-warm humid weather favours disease infection and development. Pustules are oval to elongate on the leaf with a mass of red-brown powdery spores. These sometimes turn black late in the season. Plant resistant hybrids as chemical control is not usually economic.

See Common rust photo.

Polysora rust or tropical rust or southern corn rust (Puccinia polysora) is an important disease in tropical areas. Warm, wet weather favours infection and disease development. Drizzly rain or even heavy dews allow disease formation. Pustules are small circular and orange in colour. They are evenly spread over the leaf surface. Pustules on the midribs, ear husks and tassels may be elongated or irregular in shape. With heavy infections, leaves may die prematurely, and defoliate from the base up. Plant resistant hybrids as chemical control is not economic.