"Irrigation should be scheduled, using an accurate, validated system," he added. "Be prepared to apply every four-to-six days, depending on rainfall and evaporative demand."
He explained that soil moisture deficits should not exceed 9mm on sands and 17mm on silt loams - and should be maintained for three-to-four weeks after tuber initiation.
"If soils are dry, start irrigation when the first plants initiate tubers, so that no more than 50 per cent reach that stage by the time the field has been irrigated. A repeat application may be needed within three to four days if ridges remain dry.
"Ceasing irrigation after two weeks will still allow scab to infect tubers and could actually exacerbate disease levels."