GRAINGROWERS are rightly concerned about mouse numbers in cropping paddocks around Victoria’s Wimmera and Mallee regions.
The Birchip Cropping Group (BCG) was told at its recent Trial Review Day that mouse numbers for the 2017/18 summer had increased more sharply than normal, or expected, for that time of year.
CSIRO researcher Steve Henry told the group that there had been a lot of food available in stubbles, and the weather had been mild.
That scenario was also linked to a forecast for average rainfall.
Models were predicting a moderate chance of an outbreak.
Anecdotal reports from all cropping regions for the 2018 summer was that there were higher than expected numbers for this time of year.
Mr Henry said they were not plague numbers, but higher than expected, and that farmers needed to “get out of your vehicle and go for a walk”.
“Even with an average stubble it will be masking the signs of mouse activity,” Mr Henry said.
“You need to monitor numbers.”
He said to look for active burrows in a metre-wide strip.
“Try to reduce food available, spray out germinations and use stock to reduce the food available,” he said.
“Be prepared to bait in the lead-up to sowing.
“If you push food low enough at that eight to six-week margin, and you still have a problem with mice, do an application then.
“Then measure how effective that application was before deciding whether to apply bait off the back of the seeder.
“Don’t wait; most of the damage is done in the first 24 to 48 hours after sowing and continue to monitor.”
He said to use Zinc Phosphate at one kilogram a hectare.
“Use the label rate - you only have one chance,” he said.
The key to success was in reducing the amount of grain left on the ground after harvest.
“We need to develop strategies using our current control methods to get a “better bang for our buck,” he said.
He said part of that was developing a reporting system to provide reliable information in the short term.
The 2016 harvest was a bumper crop and the harvest window was short, and along with a number of weather events, that meant there was a large amount of grain left in the paddock.
Mr Henry said that led to residual grain left on the ground of up to a tonne per hectare in some areas.
The other factor that led to problems with the sowing of the 2017 crop was the level of stubbles remaining from the 2016 bumper crop.
Lots of food and shelter from spring of 2016 into the autumn of 2017 meant the sowing of the 2017 crop was problematic.
Mr Henry said the 2017 crop “wasn’t an easy one”.
He said it was sown with significant mouse damage, but after a better than average start in many cases.
The winter got dry, there were frosts, however mice persisted because of residual food and that meant there were multiple bait applications through the crop.
The result was that farmers went into the 2017/18 summer with significant amount of food still on the ground after what was a “pretty average harvest”.
