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A reminder of aphids

There have been several reports of “higher than usual numbers” of aphids across most regions in Victoria and NSW this season. However, the recent cooler weather has slowed the rate of aphid development. Agronomist, Phillip Bowden (NSW DPI), says oat aphids and cowpea aphids can be found on a variety of cereal and pulse crops around Cootamundra, in the South West Slopes of NSW. Although the numbers are low, populations can increase (or decrease) rapidly in response to environmental factors, particularly temperature. It is therefore important to monitor crops throughout the season and to be aware of those crops where aphids are currently present.

Oat aphids (Rhopalosiphum padi) can be found on all cereals including wheat, barley and oats. They vary in colour from olive-green to black and are characterised by a dark reddish patch on the tip of the abdomen. Adults are pear-shaped and have antennae which extend half the body length. Oat aphids suck sap, causing yellowing and stunting of plants. They can also spread barley yellow dwarf virus. Click here for images of oat aphids and refer to PestFacts Issue No. 2 for further information.

Cowpea aphids (Aphis craccivora) favour legume hosts and are commonly found on faba bean, lentil, medic, lucerne, clover and lupins. The cowpea aphid is easily distinguished from other crop aphids. To look at, adults are shiny black and nymphs are dull grey in colour. All stages have white and black coloured legs. They tolerate warm dry weather and can cause severe damage to water stressed plants. For further information on cowpea aphids, refer to PestFacts Issue No. 2.

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