Smullen was aboard Miss Isabela with Colm O'Donoghue on Tubbertown Rose in the six furlongs event.
The stewards spotted Smullen elbowing O'Donoghue inside the final furlong and took swift action.
He will now be on the sidelines from September 29 to October 16 inclusive, which will include Prix de L'Arc de Triomphe weekend in Paris.
It will certainly add spice to the jockeys' championship. Smullen, twice champion previously, leads his only realistic rival, Kieren Fallon, by 65-52.
Wayne Lordan continued his terrific campaign in this race, coming in for a chance ride on the winner, Tiffany Gardens.
Robbie Burke was to have partnered Tom Hogan's mare, but missed the meeting because his father, Paddy, is currently very ill.
Lordan swept up on the outside in the closing stages to score going away by three lengths.
Don't Be Bitin, off the track since Punchestown in April, made a smashing seasonal debut when landing the featured Listowel Supporters' Club Lartigue Handicap Hurdle.
It was a superb training performance on the part of Eoin Griffin, to have his charge fit and fancied to land a very competitive contest.
Ruby Walsh made the long surge for glory coming away from the fourth last on Don't Be Bitin, after the front-running Hurricane Alley had blundered away his prospects at the flight.
Cellarmaster was soon out after the leader and the pair were locked together for much of the straight
The last hurdle was omitted, with Davy Condon, who took a crashing fall when Madam Leader fell on the first circuit, lying prone on the turf.
In the final hundred yards or so, however, it was the winner who found more to beat his gallant rival by a length.
Commented Walsh: "He was good, he's tough. They went some gallop, they absolutely flew."
Said Griffin: "It's a nice pot with which to start off. I have no firm plans, but believe there's a decent handicap in him this season."
Condon was down for a long time, but escaped largely unscathed, sore but relatively okay.
Pat Smullen, if in the mood to eat, surely guaranteed himself a decent dinner last night after powering Kempes, trained by his wife, Frances Crowley, to a head victory in the Brandon Hotel Median Auction Maiden.
The winner and well-regarded Tommy Stack newcomer, Disclosure, went toe-to-toe in the final furlong with Kempes showing the greater resolution close home.
Commented Smullen: "The second headed me, but my horse fought back well. He wants to go a mile and will make a nice three-year-old."
Robbie Burke missed a second winner when Declan McDonogh successfully deputised for him on Skerries in the Irish Stallion Farms' EBF Fillies Handicap.
McDonogh gave the mare a powerful drive, taking full advantage of a good draw and having her on the pace from the start.
Skerries was in front before the home turn and answered every call in the closing stages to resist the late surge of Peineve by a short head.
McDonogh completed a double when guiding Chiado to a seven lengths defeat of market rival, Aidan O'Brien's Born For Glory, in the Irish Stallion Farms' EBF Maiden.
The son of Daylami didn't appear overly happy on the track, but there was only going to be one outcome once the pilot drove him ahead off the home turn.
Said McDonogh: "It was only his second run and he didn't know what to do. He's a nice horse and ran to the line very strong."
Davy Russell is enjoying an excellent week and he took his total to three when winning the Kerry Petroleum Handicap Chase on 20-1 shot Dans Dealer.
The ten-year-old bounded across literally every obstacle and was taken to the front four from home. He showed no signs of stopping in the straight to easily beat Chevaux Loco.
Trained just off the Curragh by Nicky Nelson, Russell said of his charge: "He's a great jumper, very economical."
The layers got a tasty result when dual point-to-point winner, Boolakraken, swept through late to win the Listowel Printing Works Maiden Hurdle for Paul Flynn and Newmarket-on Fergus handler, Pat Lynch.
"We thought she was a stayer and wanted three miles", said Lynch, who bred the mare himself
Betting with the bookmakers was up marginally on a year ago at €1,066,557, as against €1,058,289.
Biggest betting race of the day was the €242,046 wagered on the concluding maiden hurdle, most of it remaining firmly in the satchels.