Green peach aphid’s Indonesian name is "kutu daun" and its scientific name is Myzus persicae.
Aphids differ from similar insects because they have two tubes called cornicles on the end of the body. Use a 10 times magnifier to see them to positively identify aphids.
Adult aphids can be winged or wingless. Winged adults invade crops and produce live nymphs which grow to become wingless adults. When populations on leaves are high, nymphs become winged adults.
Green peach aphid adults are 2mm long. Nymphs and wingless adults are usually green but can be yellow to pale brown. Winged adults have black patches.
Another species, the potato aphid (Macrosiphum euphorbiae) also breeds in potato crops. It is green and up to 3mm long.
Winged adults invade crops and produce live nymphs which grow to become wingless adults.
Green peach aphids damage potato crops by:
- sucking sap (but many aphids must be present before they affect plant vigour)
- spreading viruses.
Minimise virus infestion levels by:
- removing nearby sources of virus particularly plants in the potato family such as self-sown potatoes, tomatoes, chilli, tobacco and the weed nightshade
- planting seed that has low levels of virus, for example certified seed
- remove virus infected plants and any associated tubers growing within a crop.
Aphids can invade crops from emergence onwards.
Seed potato crops must be protected from the green peach aphid because it introduces and spreads viruses. Apply systemic insecticide in the planting furrow.
Monitor crops weekly after emergence by checking the underside of 100 lower leaves across the crop; include crop edges.
Aphids are most abundant at the change of seasons such as winter to spring and summer to autumn. Aphids are less likely in hot weather of summer and cold weather of winter.
For seed crops, spray when 5% of leaves are infested with nymphs and adults (five of 100 leaves).
For non-seed crops, some aphid infestation can be tolerated because a wide range of natural enemies help control the aphids.
The most common beneficial insects are wasps. Adult wasps lay an egg inside the aphid. After the wasp grows, the aphid body swells up and is called a "mummy". The adult wasp chews a hole in the mummy to emerge.
Other natural enemies feed on aphids directly - hover fly maggots, ladybirds and lacewings. When humidity is high, fungal disease can kill aphids.
Funding for this work to support Indonesian potato farmers and WA seed potato exports was provided by ACIAR (Australian Centre for International Agricultural Research) and the Department of Primary Industries and Regional Development, Western Australia.