Mice: Are they moving in again?

Cover of  "Mice: no food, no shelter"

Current indications are that mouse numbers may increase over the summer and cause a problem in the autumn in NSW, particularly in summer cropping areas, and in Queensland, particularly on the Darling Downs. Monitoring is advised. Inventories of bait and the technical active, from which bait is made, are adequate to meet all foreseeable contingencies.

The risks associated with continuing mouse activity include:

  • damage to late-harvested winter crops
  • mice taking seed sown for summer crops
  • mice damaging summer crops as they mature
  • the possibility of mice taking seed which will be sown for next season's winter crops.

To minimise these risks, consider the following actions.

During harvest

  • Minimise grain lost at harvest:
  • carefully set combs and sieves
  • fit harvester with a screen or double screen to capture broken and pinched grain and weed seeds
  • use air fronts and crop lifters to lift lodged stems.
  • Harvest crops with the most mouse damage first.
  • Clean up any concentrated spillage of grain, particularly around field bins, augers and silos.
  • Graze stubble as soon as possible after harvest, but leave sufficient ground cover to minimise potential erosion.
  • Take precautions to avoid contamination of stored grain.

Before and during sowing

  • Monitor for mice in and around paddocks adjacent to grain crop paddocks.
  • Clear surrounding areas of harbour, remove debris and control weeds and grass growth.
  • Implement a perimeter baiting program if necessary.
  • Avoid planting dry; sow when soil is moist enough to allow immediate germination.
  • Sow as deep as agronomically possible, appropriate to each crop.
  • Sow to an even depth.
  • Cross-harrow, diagonal roll or prickle chain after sowing.
  • Do not direct-drill into heavy stubble.
  • Consider changing crops in rotation.
  • If mice are present prior to sowing: consider sowing at a higher rate to compensate for potential loss of seed grain to mice. Farmers should consult an agronomist before taking this action as sowing rate has serious implications for summer crops.

A frequently asked question

Q: When must a person be accredited to handle or transport zinc phosphide bait?

A: A person must be accredited when undertaking any activity that carries a risk of exposure to the bait or its fumes. This is what is meant by 'handling'. In practice this means that bait should be safe to move and transport, provided the seal is unbroken. Opened, damaged or partially used drums should be handled only by accredited people or, in the case of aircraft loaders, those supervised by an accredited person.

In addition to permit requirements, commonsense also indicates that a person should be accredited before undertaking any activity where a risk of exposure seems likely. The bait should never be transported in any vehicle where it cannot be carried separately from the driver and passengers. So the tray of a utility is acceptable, but the back of a station wagon or sedan is not! Personal protective equipment should be worn in all cases when handling actual bait.

*Excerpted from The Mouse Trap, the NSW Agriculture Mouse Newsletter, courtesy of NSW Agriculture. The Mouse Trap is available on-line at www.agric.nsw.gov.au/pests/vp/mice and is updated regularly.

The GRDC has produced Mice: No Food, No Shelter, a practical, informative videotape for grain-growers containing best-practice mouse-management strategies.

Contact: Maureen Cribb, GRDC 02 6272 5525

Cost: $20 plus $5 postage and handling. Discount prices for bulk orders.

Region North, South, West, National