PHILADELPHIA -- The Phillies have made their share of mistakes on the basepaths this season.

That includes Juan Pierre, who has been caught stealing twice and been picked off once. He also was thrown out at second base while trying to advance on a wild pitch Sunday. That is four outs on the bases in one month.

Phillies manager Charlie Manuel was asked prior to a 6-4 win over the Cubs if there is any way to cut down Pierre's outs on the bases.

"If I take the green light off him, I don't know what that does," Manuel said. "That sends him a pretty big message. I want him to be aggressive. That sends him a message that I don't think he can run. I definitely don't want to do that."

Pierre's aggressiveness paid off in the series finale against Chicago. He entered the game in the eighth inning as a pinch-hitter for Chad Qualls and was hit by Scott Maine's first pitch of the at-bat. One out later, Pierre went from first to third on Jimmy Rollins' soft single, and he scored the go-ahead run on Placido Polanco's double.

Thome's availability puts Phils in tight spot

PHILADELPHIA -- Jim Thome needs at-bats to be productive, but because of his bad back, at-bats will be difficult to find.

Thome injured his back Saturday. He did not play Sunday and also sat out on Monday in a 6-4 win over the Cubs at Citizens Bank Park.

Thome is currently 2-for-18, with three walks and 10 strikeouts this season. Phillies manager Charlie Manuel was starting to think Thome could play at least twice a week at first base while Ryan Howard is on the disabled list, but then Saturday's injury happened.

So knowing that Thome needs at-bats to stay sharp, but he can't seem to stay healthy if he plays first base, can he be productive?

"It's going to be hard for him," Manuel said. "You never know when he might walk up there and catch one, though. You never know. When he puts a swing on a ball he's usually going to move it. That's the upside to it.

"His problem would be because of his swing. He takes a big stride. He takes a cut. He takes a hard, quick cut. You've got to get your timing. There's got to be some kind of timing. The ideal pinch-hitter usually is a short guy with a short, quick swing, and he's a singles hitter. That's the ideal, but at the same time, in the National League, you need a guy with power. A big [guy] sitting on the bench that take a swing and tie or win a game for you."

If Thome only pinch-hits, it will be difficult for him to get 100 at-bats. And it is nearly impossible to be an effective hitter over the course of six months with just 100 at-bats.

"If you get 50 to 100 at-bats over the course of a year, you ain't going to hit nothing," Manuel said. "If you hit .200 you'll be lucky. But those hits you get might win some games and tie some games up for you, which is OK."

Phils announce Home Runs For Trees program

PHILADELPHIA -- The Phillies, ARAMARK and Pennsylvania Horticultural Society announced "Phillies Home Runs for Trees" program on Monday at Citizens Bank Park, which aims to restore tree coverage in the area.

For each home run the team hits this season, the organization hopes to plant a tree. Entering Monday's game against the Cubs, that total stood at 14.

The initiative is part of PHS' Plant One Million program, a tree-planting campaign in 13 counties in southeastern Pennsylvania and parts of New Jersey and Delaware. For each home run hit by a Phillies player, PHS and its partners will plant a tree in locations like local parks, urban settings and watershed areas.

For more information on the program, or to learn how to help plant trees in the area, visit www.phillies.com/redgoesgreen.

Worth noting

• Phillies infielder Michael Martinez, who is on the disabled list with a broken right foot, visited team physician Michael Ciccotti on Monday at Citizens Bank Park. Martinez no longer needs his walking boot and will head to Clearwater, Fla., to continue his rehab.

• Ryan Howard started his rehab from left Achilles surgery Monday in Clearwater, Fla.

"Feels good to be on the grind again," he tweeted. "Beast of a workout today."

Chase Utley, who is recovering from a chronic left knee injury, could join Howard in Clearwater next week.

• The Phillies placed right-hander David Herndon on the 15-day disabled list because of right elbow inflammation. Herndon said he started to feel discomfort Monday. The Phillies will make a roster move to replace Herndon before Tuesday's series opener in Atlanta.