Russian wheat aphids found at Geraldton
- Grass Patch
This week Russian wheat aphid (RWA) activity was reported for the first time in Geraldton to the PestFacts WA team. The RWA were found at DPIRD’s Geraldton Research Support Unit in wheat. Colonies of RWA and oat aphids were found on the same plants. Tips on how to distinguish RWA from other cereal aphids are mentioned later in the article
RWA has become widespread across the grainbelt of WA, since being discovered in the Esperance region in August 2020, but this is the most northern point for RWA occurrence reported so far.
RWA has also been found at below threshold levels in wheat and barley crops in Cunderdin, Woodanilling and Grass Patch areas.
RWA can occur on a wide host range of more than 140 species of cultivated and wild grasses within the family Gramineae, with wheat and barley being the most susceptible. Oats are not considered to be susceptible to damage from Russian wheat aphid.
Diagnosing Russian wheat aphid
RWA are small in size, green in colour, elongated in shape with very short antennae and an apparent lack of cornicles (exhaust pipes).
In addition to RWA, corn aphids and oat aphids are another two abundant species of cereal aphids in WA. Corn aphids are light green to dark green in colour and are usually detected by the two darker patches at the base of each cornicle (siphunculi). Oat aphids are olive-green to greenish-black in colour and are mostly identified by a dark rust-red patch on the tip of the abdomen.
How to monitor for Russian wheat aphid
When monitoring for RWA, look for streaking damage near the base of newly emerged leaves. Aphids prefer to feed on the base and sheath of younger leaves of plants and are often found on the last two leaves unfurled. Damage symptoms include longitudinal rolling of leaves, forming a hollow tube inside which aphids conceal; whitish, yellowish to pink-purple chlorotic streaks along the length of leaves. Damage symptoms may appear a week after infestation.
While scouting for RWA, keep an eye on the edges of wheat and barley crops, or on the stressed plants.
Symptoms of RWA damage can be confused with nutrient deficiency, herbicide damage, mite feeding damage or wheat streak mosaic virus damage symptoms.
RWA is manageable with the application of registered insecticides.
Growers are always advised to apply sprays only if threshold levels are reached. Researchers from SARDI and Cesar Australia have developed a calculator to help consultants and growers decide if spraying for RWA is economically justified. For instructions and more information on using the RWA threshold calculator, refer to GRDC’s Russian wheat aphid page.
For a list of insecticides registered for use on aphids (including RWA) see DPIRD’s 2022 winter spring insecticide guide or refer to the Australian Pesticides and Veterinary Medicines Authority (APVMA) products database for all chemical control options available for RWA in grains crops.
To read about earlier RWA activity this season refer to the 2022 PestFacts WA Issue 8 article Russian wheat aphid.
For more information on RWA refer to the:
- DPIRD Russian wheat aphid: production pest page
- Cesar Australia Russian wheat aphid identification PestBites video
- GRDC Russian wheat aphid page
- GRDC Just how many Russian wheat aphids is too many podcast.
For more information on RWA, or other aphids, contact Research Scientist Svetlana Micic, Albany on +61 (0)8 9892 8591.
Article authors: Saleh Adnan (DPIRD Geraldton).
Article input: Svetlana Micic (DPIRD Albany).