Aphids damage plants by direct feeding and causing the spread of viruses. Direct feeding damage depends on several factors including the growth stage of the crop and the number of aphids per tiller. Aphids affect the stems, leaves and heads of the plant from seedling stage through to head filling.
The Department of Agriculture Western Australia suggests aphid feeding can cause damage by reducing yields of up to 10% as well as reducing grain size. Direct feeding damage occurs when colonies of aphids develop on stems, leaves and heads from seedling stage right through to head filling. The degree of damage caused by aphid feeding is dependent on percentage of tillers infested, the number of aphids per tillers and the duration of infestation.
Feeding damage often has no obvious signs or symptoms, however heavily infested plants may be covered in black sooty moulds, which live on the sugary honeydew excreted by aphids.
Oat and corn aphids cause most yield loss and are also the primary vectors of BYDV.
- Treat the seed with a recommended seed treatment (e.g. Guardian)
- Choose resistant varieties
- Time of sowing