Aspergillus rot / Aflatoxin contamination rot: Aspergillus flavus and A. parasiticus

Symptoms:

• Appears as an olive-green mould on the kernels from the tip of the ear
• Fungal spores appear as powdery and may disperse like dust when you pull back the husk
• Fungus produces a mycotoxin known as aflatoxin (B1, B2, G1 and G2)
• Aflatoxin affects grain quality and marketability, as well as livestock health if the grain is consumed
• Aflatoxin is extremely carcinogenic and most countries have regulations (20 ppb)

Favourable condition:

• During hot, dry years on stressed plants
• Feeding damage from ear-invading insects and injury by birds or hail

Mode of Spread:

• The fungus survives in soil or crop residue and infects ears during late silking
• Spores are spread by wind and insects and infection takes place through wounds or the silks

Management:

• Maize must be dried to below 14 percent moisture
• Reduce the stress to the crop during harvesting
• Avoid wound in kernels by insects/birds
• Appropriate fertility to the crop