CANOLA growers have been warned of a narrowing planting window, following a variable start to the growing season.
As a result of the mixed start, canola sowing has been delayed in several areas, particularly in the eastern and northern regions.
The Department of Agriculture and Food WA (DAFWA) has examined the impact of delayed sowing on canola yields.
DAFWA development officer Jackie Bucat said there was a similar rate of yield loss across the field trials after mid-May.
“Average yield losses were 15 kilograms per hectare per day for the last week of May, increasing to 25kg/ha/day in June,” Ms Bucat said.
“I expect these results to be reasonably robust because of the similar rate of loss in most trials, although there were obviously big differences in actual yields for different locations.”
Ms Bucat urged growers to consider a canola crop’s yield potential carefully and compare it to the potential returns from an alternative cereal crop or other options.
“The opportunity to plant canola in low rainfall areas north of Merredin has most likely passed and there could be more profitable crops to sow than canola – keeping in mind the impact of changing the crop rotation - or giving paddocks a rest,” she said.
“Growers in low rainfall areas with a cooler finish, such as the Lakes district, probably only have until the start of June to sow a canola crop before potential yields drop too low.
“In high rainfall areas where a cooler finish to the season is more likely, such as Kojonup, the modelling shows that canola is still a good proposition until the end of June, after which pasture might be a better option.”
DAFWA has refined research to model the differences for five locations, using historical rainfall data and 2017 rainfall up to mid-May.
The modelling compared canola yields sown at 10-day intervals from 10 May to 29 June at Mullewa, Wongan Hills, Merredin, Kojonup, and Gibson from 1976 to 2016.
