Primary industries have between three and 15 years to investigate methods to control grass grub without three commonly used insecticides, including diazinon, the only current agrichemical option for post planting larvae control. A number of natural pathogens can control grass grub (biocontrol), however summer drought and cultivation can be detrimental to the survival of biocontrol organisms. Non-chemical control options include physical damage to grubs and pupa though cultivation, trampling and heavy rolling. Under a traditional one year life cycle, damage caused by grubs can occur any time from February to August depending on grub size and feed supply. If two year life cycle grubs are present, damage can occur from August to December e.g. late spring early summer damage in late planted peas. Each female grass grub lays one main egg batch close to where she emerges (the damaged patch) and may also lay a few eggs some distance from the emergence point during a feeding flight in November. Adult feeding flights are the main method of grass grub dispersal into new areas.
No. 106 Grass grub biology and non chemical control
