Raymond Lamb is accused of causing Yvonne Lumsden’s death by driving dangerously on the A948 Ellon to Auchnagatt road on July 12, 2019.
It is alleged the 30-year-old was driving a Mitsubishi L200 pick-up at “excessive speed” while towing a trailer which had a “defective” braking system and was not secured properly.
The charge states the trailer detached from the Mitsubishi before hitting Mrs Lumsden’s Volkswagen Polo.
The 35-year-old, from New Deer, was so badly hurt she later died in hospital.
A child in her vehicle is also said to have been seriously injured.
Lamb, of Peterhead, faces a further three charges under the Road Traffic Act.
Defence counsel David Moggach entered a not guilty plea for Lamb when the case called at the High Court in Glasgow.
He said: “Put shortly, we are ready to proceed to trial, but one cannot be fixed at present.”
Lady Stacey instead adjourned until a further hearing in September.
After the tragedy, Mrs Lumsden was described as a “kind” and “cherished” teacher who was loved by pupils at Stuartfield Primary.
Neighbours described her a “dedicated” mum to her two daughters and husband Stuart, and described them as a “perfect little family”.
The crash happened near the A948’s junction with Golf Road, just north of Ellon, on Friday, July 12 2019.