It was only Welbeck's second appearance for North End after he joined the club on loan until the end of the season.
Ferguson said of Welbeck's goal: "You may call it cheeky but it was one hell of a finish.
"He showed great composure but we've got to be careful we don't place too much responsibility on him.
"He's only 19 and has come into a really hard league that he has never played in before.
"But as soon as he scored you could see the shackles come off and he grew in confidence.
"You would pay to see that sort of goal alone. What a magnificent finish."
Preston opened the scoring when substitute Collins, who had only been on the pitch five minutes, rose highest to greet Richard Chaplow's right-wing cross with a firm header.
Collins had replaced Youl Mawene at the heart of the defence and it was his first goal for the club.
Welbeck then showcased his undoubted class with his stunning strike to seize centre stage six minutes from time to give Preston their second successive win.
The result allowed Ferguson to get one over his former Old Trafford team-mate Roy Keane.
But the Scot insisted: "This wasn't about me or Roy.
"Roy is a good lad and the fact he was involved today had nothing to do with it.
"Ipswich had only lost one of their last 15 so this was a good result for us."
Ferguson revealed Celtic have still not come close to matching North End's £4.5million valuation of highly-rated defender Sean St Ledger.
He added: "We need one or two new faces to freshen things up and I am pushing the chairman as much as I can.
"The situation with Sean St Ledger hasn't changed. Celtic are a million miles away and they aren't going to get him with what they have offered and as a manager there's no way I want him to leave.
"He's one of the best defenders in the league and I think Celtic should stop messing about to be honest.
"They either give us what we want or finish it - simple as that."
Defeat was harsh on Keane's Ipswich, who had lost only one of their previous 15 outings and were neat and tidy in possession but struggled to create genuine goalscoring opportunities.
Preston were not much better, but they upped the tempo after a dreadful first 45 minutes and just about deserved their win.
Keane blasted his relegation-threatened side's defending and said: "From our point of view the first goal came from unbelievably bad defending.
"We don't score enough goals so we are putting ourselves under pressure all the time."
Ipswich have been linked with a move for Cardiff striker Michael Chopra and Keane said: "Chops is a very, very good striker.
"Whether our club can afford him on his wages remains to be seen."
Source: Team Talk
Source: Team Talk