AUBURN – The nearly 150 golfers who will tee it up Tuesday for the 90th Charlie’s Maine Open at Fox Ridge Golf Club and a gaggle of kindergartners opening a coloring book for the first time will share something in common this week: A warning to stay between the lines.

Fox Ridge, in the third year of its initial three-year deal with the Maine State Golf Association to host the state’s top professional tournament, has always been a tough test from the rough, especially from the long, wispy fescue that lines many of the links-style course’s holes.

With all of the rain this summer, the rest of the rough – now up to three cuts deep- is perhaps even more penal than before.

“It’s gnarly out there,” Fox Ridge head professional and director of golf Bob Darling said. “The person who wins here this week is going to have stayed in the fairway.”

Course co-owner and superintendent Ed Michaud also played in the annual pre-tournament pro-am on Monday.

“It’s a stroke penalty for most of these players out of that rough,” Michaud said.

And while the weather – and the subsequent course conditions – have dominated golf course conversations all summer, not lost on the MSGA is the jump in the number of golfers who have signed up to play in this year’s edition of the Maine Open.

“We have our biggest field since we brought the tournament to Fox Ridge,” MSGA executive director Nancy Storey said. “I think more people are learning about the golf course, and more people are realizing how good this course really is.”

This year, Fox Ridge received a 4-star rating from Golf Digest magazine, which has helped to boost interest from around the region.

In addition to better publicity about the course, though, entries are also up at this year’s Maine Open thanks to the Davis Richardson Senior Division. Richardson, an Auburn native who has been a fixture at the MSGA for decades, also played in Monday’s pro-am.

“It’s a 36-hole event within the tournament, and the golfers are playing for five thousand dollars,” Storey said. “That’s a separate pool of money, too, from the main tournament.”

Last year, Darling double-dipped, winning both the Maine professional division and the senior division.

“Most of our regular Maine pros now qualify for that senior prize,” Storey said. “It’s wonderful for them to have an extra prize. The fact that it’s sponsored in Dave’s name, too, means that they don’t have to pay an extra entry fee to be eligible for it.”

And while the numbers may have swelled a bit thanks to the over-50 crowd, the main focus of this year’s tournament will still be on the youth.

Shawn Warren, who won the Maine Open as an amateur in a playoff in 2004, fired a 65 in Monday’s pro-am.

“I wish I’d saved that one for (Tuesday),” Warren quipped after his round. “The greens right now are so much softer than normal, so you can go right at them, and the fairways are holding now with the wet weather, so where your ball used to bounce through and go into the rough, you can hold the fairways now.”

Seventeen-year-old Ryan Gay, who has already won the Maine Amateur and Maine Junior Championships this summer, will look to become only the second golfer in Maine history to win the Maine Open on top of those two. The late Jim Veno captured all three in 1961.

Gay fired a 71 in the pro-am on Monday, one shot more than perennial amateur contender Mark Plummer’s 70. Former top Maine amateurs who have recently turner pro, including Waterville’s Toby Spector and Clinton’s Ross McGee, are also younger players to watch.

Eric Egloff of Maryland, who has been in contention in the past, leads a long list of solid regional professionals into the tourney.

Golfers will tee off in threesomes beginning at 7 a.m. Tuesday.