Diagnosing aphids in narrow-leafed lupins
Main species affecting lupins are cowpea aphid (Aphis craccivora), bluegreen aphid (Acyrthosiphon kondoi) and green peach aphid (Myzus persicae). Two other minor species sporadically recorded on lupin are the leafcurl plum aphid (Brachycaudus helychrisi) and potato aphid (Macrosiphum euphorbiae). High numbers of aphids in lupin crops can cause stunted growth and affect flowering and pod set. Aphids also transmit two important diseases in lupins: cucumber mosaic virus and bean yellow mosaic virus. Refer to see also section for more information on viruses.
What to look for
- Wilted plants with aphid clusters on buds and flowers that result in flower abortion.
- Adults and nymphs are found on the plants at the same time. Winged adults may be present.
Correct identification of the aphids is critical. Green peach aphids are resistant to many insecticides, but tend to be found on the underside of leaves. Other aphid species usually found on buds and flowers.
- Aphid infestations can be in hot spots or spread through out the paddock.
Where did it come from?
- Aphids move into lupin crops from pasture, weeds.
- Rainfall in late summer and early autumn encourages survival of aphid host plant material, leading to early aphid flights into crops soon after seeding.
- Some narrow-leafed lupin varieties are quite resistant to aphid colony development.
- Controlling aphids when 30% of flowering buds have 30 or more aphids will give a yield response.
Economic and financial considerations
How can it be monitored?
- After buds start to appear on the crop, check 15 plants at four different sections of the paddock. Look on the youngest inflorescences.