Grass grub larval populations in many irrigated or summer moist regions (e.g. Canterbury and Southland) appear to be similar to previous seasons, and despite the dry summer, large numbers can still be found on dryland properties too, suggesting that summer rainfall (likely the late December rainfall that was so valuable for crop production) was adequate to ensure survival.
Key points
- Grass grub larvae are still about in irrigated and dryland regions, despite the dry summer.
- Size variability in some larval populations suggests they are likely to keep feeding into and possibly through the winter.
- Consider using seed treatments or granular insecticides at sowing.
- Check for grass grub larvae now in areas which have previously had grass grub issues or in rotation positions where larvae populations are generally high (e.g. following 2nd year white clover seed crops).
- Keep monitoring throughout the winter.
For more information on this year’s grass grub situation and on grass grub biology and management see the following FAR publications:
Arable Extra 111, Chemical control of grass grub
Arable Extra 106, Grass grub biology and non-chemical control