Patterson, 51, is seeking to quash her murder convictions in the Victorian Court of Appeal for serving lunch guests a death cap mushroom-laced meal in July 2023, arguing she suffered a substantial miscarriage of justice.
One of her grounds of appeal is that she was "forced" to give evidence at trial because the trial judge excluded mushroom photos.
Her barrister Veronika Drago pointed to the judge's decision to not allow the photos from 2020 found on Patterson's SD card into evidence.
The defence wanted to use those photos to show Patterson always had an interest in foraging for mushrooms, Ms Drago said on Wednesday.
Without the images, the only way jurors could hear evidence of foraging was through Patterson herself, the barrister argued.
But crown prosecutor Jeremy McWilliams refuted that claim on Thursday morning, saying Patterson seemingly always intended to give evidence.
He noted there was no evidence that Patterson had previously foraged, citing her police interview, in which she denied any interest.
Mr McWilliams also referenced statements from Patterson's family and friends who did not have recollections of her foraging.
But Patterson's trial barrister submitted in his opening address that she had lied in the police interview and she always had an interest in foraging, Mr McWilliams said.
"(Patterson) would need to give evidence about those matters given the evidentiary landscape," the prosecutor said on Thursday.
"Both to overcome the lie but also the suite of evidence that tends to support the lie."
Mr McWilliams denied that simply tendering the photos to the jury would have been sufficient.
The prosecutor also refuted the claim Patterson's cross-examination was unfair and oppressive, instead arguing the trial prosecutor had been fair and careful.
"Plainly, we reject any suggestion the prosecutor acted as anything other than a model administrator of justice," Mr McWilliams said.
The prosecution will continue to respond to Patterson's appeal grounds before turning to their cross-appeal on her sentence later on Thursday.
Victoria's top prosecutor Brendan Kissane KC is expected to argue the decision to grant Patterson a non-parole period of 33 years was manifestly inadequate, and life without parole should have been the sentence.
Patterson was jailed after a jury found she deliberately served beef Wellingtons laced with death cap mushrooms to her former in-laws Don and Gail Patterson, 70, and Gail's sister Heather Wilkinson, 66.
The three guests died after a July 2023 lunch at Patterson's Leongatha home, in regional Victoria, while Heather's husband Ian fell seriously ill from the meal but survived.
Patterson was also convicted of Mr Wilkinson's attempted murder.
Mr Wilkinson and other members of the Wilkinson and Patterson families were back in court on Thursday, alongside members of the public and dozens of journalists.
The appeal hearing before Justices Stephen McLeish, Lesley Taylor and Peter Kidd continues.
