Head Scab of Wheat

Fusarium graminearum Group 1

Names:

Fusarium Head Blight.

Description:

Part or all of the Wheat head is white or yellow and often without grain or with shrivelled and pinkish grain. Pink or orange fungal strands may be over the head.

Species Affected:

Wheat, Barley, Durum Wheat, Maize, Triticale, small grain cereals, grasses.
Durum Wheats are more susceptible than bread Wheats and Barley.

Biology:

Favoured by warm (20-300C), humid, moist conditions with leaves remaining wet for 36-72 hours during the flowering of the crop.
Causes sterility of the flowers, shrivelled and low quality grain. The grain is also prone to carrying toxins such as deoxynivalenol, which causes infertility, vomiting, unpalatability and haemorrhage of the intestinal tract of animals and humans.
The fungus survives in the soil especially on cereal and grass residues.
Causes Stalk Rot in Maize.

Life Cycle:

Spores on the soil are transferred to leaves and stems of the crop by raindrop splash. If temperatures are around 20-300C infection occurs. Most infection occurs around flowering.

Origin and History:

Distribution:

Usually fairly evenly distributed through the crop.

Significance:

Yield losses in Wheat and Barley range from 20 to 100% in years favourable to the disease.
Grain is often less palatable to stock and may contain toxins.

Management and Control:

Adjust crop rotation so Wheat follows a broad-leaved crop or pasture.
Don't sow Wheat after Maize or on grassy pastures.
Burn or bury infected cereal stubble.
1 or 2 foliar sprays of tebuconazole or carbendazim during flowering of cereals provide good control.
Bacillus spp. sprays are cheaper but less effective than fungicides.

Related and Similar Species:

Copper deficiency has similar symptoms.
Take-all (Gaeumannomyces graminis)
Crown Rot (Fusarium graminearum Group 1)
Yellows of Brassicas (Fusarium oxysporum f.sp. conglutinans)

References:

Steven Simpfendorfer Ag NSW, Tamworth

Peter Hayman SARDI

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.