A study is underway to determine whether harvest weed seed control systems, which create chaff residues, are promoting pest activity and associated crop damage in the southern region.
The GRDC-funded research is being led by SARDI.
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Chaff piles, chaff tramlining and chaff lining are HWSC system methods that result in a concentrated distribution of the chaff component within the paddock, limiting weed survival.
However, some growers adopting these HWSC systems have observed increased pest pressure associated with chaff residues and they are particularly concerned about the potential risk of associated crop damage.
SARDI entomologist Kate Muirhead says the study is being conducted in 14 paddocks at various locations across the GRDC southern region, including Yorke Peninsula, Eyre Peninsula and the Mid North of SA, as well as Western Vic.
"The sites selected represent different annual rainfall zones, cropping rotations, and invertebrate pressures," Dr Muirhead said.
The trials are being managed by Hart Field-Site Group and Nutrien Cummins Ag Services in SA and Birchip Cropping Group in Vic.
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Dr Muirhead says the study will address two key questions:
- How does the presence of chaff lines or tramlines affect the species composition, density and distribution of pest and beneficial invertebrates, and the risk of plant damage, in grain crops in the southern region?
- How do microclimatic conditions in different chaff residues affect patterns of invertebrate species abundance?
"The invertebrate species of interest in the study are pests of crop establishment that reside in paddocks throughout the year - soil insects (earwigs, millipedes, slaters), molluscs (snails, slugs), earth mites, lucerne flea, and beetles/weevils," Dr Muirhead said.
"The main beneficial groups are predatory mites and beetles, ants, and organic matter recyclers such as collembola, book lice, and others."
Dr Muirhead and her team recently removed pitfall traps installed in the 14 paddocks included in the study.
The project will conclude in April 2024, and the research outcomes will inform the need for specific management of crop pests in HWSC systems and address potential barriers to their adoption by quantifying the risk to crops from invertebrate pests.
