Bats striking out: breaking bats and a wood-eating pest spell serious trouble for baseball.

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A baseball game last spring turned dangerous when Pittsburgh Pirates' player Nate McLouth drove a ball into right field with a loud "Thwack." The hit had snapped his bat in two and sent a shard of wood hurling straight toward the dugout. The flying club struck coach Don Long in the face, leaving a bloody gash and severing nerves in his left cheek.

Long isn't the only one to have suffered a serious bat-related injury. At recent games, a bat fragment fractured one fan's jaw and knocked an umpire unconscious. Broken bats have always been part of baseball, but never have so many failed so dramatically. The trend has left many pointing their fingers at maple wood, the material used to make the majority of today's bats.

"Northern white ash was the wood of choice for baseball professionals for decades," says Rick Redman, communications officer for Louisville Slugger, the big leagues' largest bat supplier (see "Batter Up," p. 18). Maple's popularity took off after Barry Bonds broke the home-run record in 2001 swinging maple bats.

Now, Major League Baseball (MLB) is deciding whether maple should remain in the game, given its dangerous record. And ash has its own troubles. A devastating blight is killing off North America's ash trees.

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SAFETY CHECK

Faced with growing safety concerns, MLB decided to have every split, chipped, or smashed game bat from a two-month period examined by a team of wood experts under the supervision of Dave Kretschmann, an engineer at the United States Department of Agriculture's Forest Products Lab in Wisconsin. Their goal: Figure out what has been causing so many dangerous breaks.

Analysis of more than 2,200 bats revealed that maple is three times more likely to shatter into multiple pieces than ash--which tends to crack and splinter. The main reason is due to the bats' slope of grain, or how straight the fibers are along a piece of wood. "The larger the angle of the slope of grain, the weaker the wood is when it bends," says Kretschmann.

While it's easy to see ash's slope of grain, maple's is harder to detect. That makes it more difficult to select the best quality maple wood for bats.

BREAKING POINT

Maple bats aren't the only ones currently on the chopping block. Traditional ash bats still used by Little Leaguers and pros alike have a problem of their own--an invasive species called the emerald ash borer.

The nonnative beetle appeared in the United States several years ago. Since then, it has destroyed tens of millions of ash trees across Canada and the Midwestern U.S (see, "How the Emerald Ash Borer Kills Trees," right). "In areas where the beetle has been for a while, there are no ash trees left," says Sven-Erik Spichiger, an entomologist who studies insects for the Pennsylvania Department of Agriculture.

In 2007, the ash borer was discovered in Pennsylvania, giving the baseball-bat industry some cause to worry. That's because the best bat-grade timber--used by the likes of Louisville Slugger--comes from forests along the Pennsylvania-New York border. "The emerald ash borer has not yet reached the area where we get the wood for our bats, but it's getting a little close for comfort," says Redman.

CRACKDOWN

With not just bats but an entire genus of trees at stake, forestry officials are working to prevent the ash borers from spreading. One step is to keep people from moving wood from bug-infested areas. Officials are even considering introducing foreign insect species that feed on ash borers to fight the pests. If all else falls, bat makers are looking into other woods, like beech, that could replace ash.

In the meantime, the major leagues have instituted new regulations to help keep maple bats in play. "Every bat was inspected closely before. Now they are really going under the microscope," says Redman. Starting this season, part of the bat-making process will include placing a small ink dot on bats. The stain allows the slope of grain to become more visible, helping weed out problem bats.

Another major change: Manufacturers will rotate the placement of logos on maple bats by 90 degrees. Players have long been taught to swing wooden bats with their logos facing up. That ensures they hit the ball with the strongest surface of the bat--the side that cuts across a tree's growth rings (annual growth layers) where the grain is closest together. The rule of thumb holds true for ash, but is the exact opposite for maple. "We're confident that these regulations will reduce the number of bat breaks that fly off into the field," says Kretschmann.

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nuts & bolts

HOW THE EMERALD ASH BORER KILLS TREES

The emerald ash borer (Agrilus planipennis) lays its eggs on the bark of ash trees.

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When the larvae (insects' immature growth stage) hatch, they burrow into the tree and begin feeding on the wood.

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A large-enough infestation will cut off a tree's ability to transport water and nutrients, eventually causing the tree to die.

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Once fully grown, emerald ash borers emerge from trees through sideways D-shaped holes.

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RELATED ARTICLE: Batter up.

In 1884, 17-year-old John "Bud" Hillerich attended a major league game in his hometown of Louisville, Kentucky. The team's star player, Pete Browning, was in the middle of a batting slump. He stepped up to the plate, only to have his bat break. When the game ended, Bud offered to make Browning a new bat in his father's woodworking shop. Browning agreed, and the pair worked all night perfecting a design hewn from white ash. The next day, wielding Bud's handcrafted bat, Browning got three hits. The teen's "Louisville Slugger" became a sensation. Pro players, from Babe Ruth to Derek Jeter, continue to make history swinging bats of Bud's design.

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web extra

For more baseball science, visit: www.exploratorium. edu/baseball

PRE-READING PROMPTS:

* Have you ever seen a baseball game in which the bat broke after a hit? What do you think made that happen?

* What are some things that you think could be done to prevent a baseball bat from breaking?

DID YOU KNOW?

* There is actually a "sweet spot" on a bat. This is the spot that transfers the most energy to the ball and sends the ball flying at the greatest speed. Players hope that hitting the ball at the bat's sweet spot will produce a home run.

* In addition to the emerald ash borer beetle discussed in the feature, the gypsy moth is another invasive species that can kill trees. Leopold Trouvelot, an entrepreneur who was trying to start a silkworm business, imported the gypsy moth to the United States in the mid 1800s. But the bugs escaped and started to wreak havoc on the trees of the Northeast. The moth's larvae eat through a forest's canopy by chewing holes in the trees' leaves. The gypsy moth favors the leaves of deciduous hardwood trees, but it will eat any type of tree if there is competition for food.

CRITICAL THINKING:

* We are learning more about medicine and technology every day, which is leading to new innovations. Some of these new innovations are helping athletes break records. Should the new records be in the same category as the old records? Should the new records be somehow footnoted because of the new technologies?

CROSS-CURRICULAR CONNECTIONS:

PHYSICAL EDUCATION: Have a "Home Run Derby"! Pitch underhanded so the students will be able to connect with the ball. Each student should get 3 chances to hit. Have the other students measure and mark the hits, and then record the measurements and graph the results. Another way to do this activity is to vary the ball or bat. For example, try a plastic bat and whiffle ball, a ruler and ping-pong ball, and a craft stick and pompom.

RESOURCES

* Learn more about the emerald ash borer at this Web site run by Michigan State University: www.emeraldashborer.info.

* Listen to a Podcast from NPR's Science Friday about the difference between ash and maple bats: www.npr.org /templates/story/story.php?storyid=92222323.

* Find out more about the science and engineering of baseball at the University of Massachusetts-Lowell's Baseball Research Center: http://m-5.uml.edu/umlbrc/index.htm.

* Want to know more about Louisville Sluggers? Check out this site: www.slugger.com.

CHECK FOR UNDERSTANDING

DIRECTIONS: Fill in the blanks to complete the sentences below.

1.--wood is the material used to make the majority of today's bats.

2. The--is how straight the fibers are along a piece of wood.

3. An--called the emerald ash borer beetle is killing off North America's ash trees.

4. To combat breaking bats, Major League Baseball is placing small--on bats to allow the slope of grain to become more visible.

5. The strongest surface of a wooden bat cuts across a tree's--, where the grain is closest together.

Answer key:

1. Maple 2. slope of grain 3. invasive species 4. ink dots 5, growth rings