Agronomists say it's time to rethink the value of the often-neglected rotary hoe. Sure it'll break crusts to help save stands. But it can provide valuable help as a weed control tool. The key is in the timing.

It was a tool and task I lived for during those warm, dusty Iowa springs of my youth. The rotary hoe, the 4020 with the good AM radio, sunshine, a sturdy ballcap, dirt flying... and best of all, a pace close to "road gear."

When dad picked me to go rotary hoeing instead of using my renowned skills with a cultivator (removing weeds in the row), my day was made. Thankfully, both my older and younger brothers had that "steer-straight" cultivating gene, you know the one that lets you concentrate on what I deemed the most boring job in the world. Nope, not for me. Rotary hoeing was the greatest gig on the farm.

Changing philosophy. We, like many Midwest farmers, dusted off the rotary hoe only when wind erosion or crusted soils appeared. Today, more than two decades removed from my glory days, agronomists emphasize a change in this philosophy.

The new science of weed biology (See "Buy into weed biology," February issue, page 4) will help make the rotary hoe more viable as a weed control tool.

Hoe by emergence. "By using our WeedCast software (a weed emergence prediction tool, based on soil temperature and moisture data), early research shows we can optimize timing to control more foxtail with a rotary hoe or a cultivator," says Frank Forcella, weed researcher at the USDA/ARS North Central Soil Conservation Research Lab in Morris, MN. "Foxtail, which is the first weed we've studied, is best controlled with a rotary hoe when 30% have emerged."

Doug Buhler, research agronomist at the National Soil Tilth Lab in Ames, IA, agrees that weed emergence prediction tools "will help add success to mechanical control, but more research is needed."

His Iowa studies with the rotary hoe were born out of a grower segment interested in eliminating herbicides. "We determined that two rotary hoe passes (at seven and 14 days after planting) can control 60 to 70% of certain early species like lambsquarter, smartweed and foxtails," Buhler says. "But once we get a better handle on predicting weed emergence, mechanical control should play a larger role to complement herbicides, especially when cost is $2 per acre."

Short of having weed biology data, the best rule of thumb to improve rotary hoe weed control is to dig in the soil to find small weeds. "If you see white roots scattered after making a pass, that's the time to hoe. If you're going into 1/2-in.-tall weeds or greater, the chance of control diminishes," Buhler says.

Tool technology. Design of the rotary hoe hasn't changed much since the early '90s. But if you're looking to upgrade from a 15- or 20+-year-old machine, here's a look at the four companies offering hoes, most priced in a $3,000 to $15,000 range.

Case offers two rotary hoes: model 181 for conventional tilled fields or 181 minimum-till for mulch-till situations. Each 21-in., 16-tooth wheel is suspended from a spring-loaded arm. Two staggered hoe ranks on the minimum-till model allow for better residue flow. Both rigs are available in rigid or folding styles, in widths from 15 to 41 ft. Contact Case Corp., Dept. FIN, 700 State St., Racine, WI 53404-3392, 414/636-6011 or circle 204.

Deere also has two models: a rigid or folding 400 series rotary hoe. The design features a choice of mainframe size, 20-in. dia. wheels with 16 teeth, walking beam connection to allow individual wheel flexibility and high-strength shank attached to each wheel, which is individually flexible and staggered. Sizes are from four 40-in. rows or six 30-in. rows to 12 40-in. rows or 16 30-in. rows. Contact Deere & Company, Dept. FIN, John Deere Rd., Moline, IL 61265, 309/765-4714 or circle 205.

M&W offers a wider variety of rotary hoes, from basic conventional-till rigs to minimum-till and ridge-till units. Its minimum- and ridge-till rigs feature unique extended rear arms to create two separate rows of wheels. The company claims that its rotary hoes clear trash better because teeth on wheels in one row remove trash from between wheels in opposite rows as they rotate. Widths range from 15 to 41 ft. Contact M&W, Dept. FIN, 1020 S. Sangamon Ave., Gibson City, IL 60936, 217/784-4261 or circle 206.

Yetter Manufacturing also offers three styles of rotary hoe, from the basic rigid or folding toolbar to its MT (minimum-tillage) series to a ridge-till rig. They feature 21-in., 16-teeth wheels, each mounted to its own malleable cast arm, which is independently spring-cushioned. Widths range from four to 24 rows. Contact Yetter Mfg. Co., Dept. FIN, Box 358, Colchester, IL 62326, 800/477-5777 or circle 207.