Green peach aphid alert
The Department of Primary Industries and Regional Development (DPIRD) staff are currently conducting ongoing aphid trapping, crop surveillance and virus testing at certain sites in the Kwinana West, Albany and Esperance regions.
Winged green peach aphids (GPA) have been detected in Northam. GPA are also infesting crops at various trapping sites in the Albany port zone.
Oat aphids have also been found infesting grass weeds around Takalarup.
Growers and advisors in the Kwinana West and Albany port zones are therefore advised to monitor young crops over the next couple of weeks.
GPA transmit turnip yellows virus (TuYV) and this virus can cause up to 50% yield losses when the crop becomes infected during the vegetative growth stages. Oat and corn aphids can transmit yellow dwarf viruses (YDVs). For more information on diagnosing and managing aphids refer to DPIRD’s Aphid management in canola crops and Diagnosing cereal aphids pages.
DPIRD has not collected any data yet for the Esperance region and is not monitoring crops in the Geraldton or Kwinana East port zones. Therefore, if growers or agronomists operating in these regions observe aphid infestation or virus-like symptoms in crops, please contact DPIRD research scientist Benjamin Congdon on +61 (0)8 9368 3499. Canola plants can also be tested for the presence of virus through the Department’s Diagnostic Laboratory Services – Pathology Services.
Impact of recent weather conditions
The growth rate of aphid populations is reduced during cold weather conditions, and when temperatures drop below 16°C aphids are unlikely to fly. This decrease in activity makes it less likely for them to cause widespread virus infections. Additionally, heavy rain can cause aphid mortality as it dislodges aphids from plants. However, if daytime temperatures exceed 16°C in the coming weeks, aphid populations in certain areas where they are already present will continue to grow and disperse. This may pose a risk to crops that are still in their vulnerable growth phase (pre-flowering). Crops that have begun stem elongation and are aphid and virus free are now in the safe zone. The use of insecticides to control certain aphid/virus combinations (such as cereal aphids/YDVs and GPA/TuYV) in these more mature crops is unlikely to provide any economic benefits.
For insecticide recommendations refer to DPIRD’s 2023 winter spring insecticide guide.
To read about earlier aphid and TuYV activity this season refer to the 2023 PestFacts WA Issue 5 article Early season aphid and virus risk in cereals and canola.
For further information contact Research scientist Benjamin Congdon, South Perth on +61 (0)8 9368 3499.
Article author: Benjamin Congdon (DPIRD South Perth).