Helping Onion Growers Grow

New pest-management products give minor crop producers a leg up

In Colorado, onions are a $50 million per year industry. Onion crops cover nearly 14, 000 acres, making Colorado one of the country's top three onion producers.

Yet onions are considered small potatoes when compared to the nation's biggest crops – wheat, , soybeans, corn, and rice. Companies that develop pest management products prefer to cater to the big guys. By controlling such pests as insects, weeds, and diseases, they save farmers thousands of dollars annually.

Scott Nissen, an associate professor of weed science, believes onion growers should have the same competitive edge. Since coming to Colorado State in 1995, he's been working for the smaller growers to do just that.

Onions have the potential to be one of the highest return-per-acre crops says Nissen, but, profits are compromised by how much farmers spend on hand labor to manage onions' most tenacious enemy::weeds.

That's where Nissen helps out. He and his collaborators develop alternative uses for EPA-approved products that effectively control weeds, thereby reducing the need for expensive hand labor.

"Onions can't stand much competition," Nissen explains. The plants have very little leaf surface area, leaving fertile fields open to weeds throughout the growing season. "You see weeds in onion fields that don't look like that weed in any other situation, because they're so much bigger and more competitive than the onions." To get maximum yields and profit margins, onion farmers must keep their fields weed-free for as long as possible.

Until recently, late-season weed control was done by hand. "Crews of hand laborers would walk the fields with small hoes and knock the weeds out by hand," Nissen explains. "Those costs have skyrocketed to where, even in a modest infestation, a grower could spend between $100 and $200 an acre."

But in 1998, farmers began using Dual Magnum, an herbicide for which Nissen developed the data to support a Special Local Need label and which now is used on 80 to 90 percent of Colorado's onion crops. The product has proven to be safe and effective, controlling Colorado's most common annual weed species. When applied to a clean field after the onions have two to three true leaves, Dual Magnum inhibits the growth of weed seedlings. Growers who apply the herbicide again four to six weeks later may realize the greatest benefit, says Nissen. "Then there isn't the need for hand labor late in the season."

The product costs about $18 per acre to apply. "If farmers can get by with one late-season application, they'll realize a considerable savings compared to the cost of labor," says Nissen.

While Nissen's work is focused primarily on onions – the Colorado Onion Association funds most of his research – he also develops alternative uses for products that often are effective with other crops, such as spinach, potatoes, and beans. He is one of several Colorado State University members of a federal program called IR-4 whose mission is to provide pest management solutions to growers of fruits, vegetables, and other minor crops in all 50 states. One benefit of participating in IR-4 is that the program pays to test and register products believed to have good crop safety and weed-control efficacy.

Registering a new product "costs anywhere from $80 to $250 million, so companies focus on the greatest return – crops like corn, soybeans, wheat, and rice," explains Nissen. "So IR-4 was developed to give minor crop growers access to the same products that are being developed for major crops. It's been extremely successful."

Under the direction of environmental and pesticide education specialist Sandra McDonald, Colorado State has become a mini-field site for IR-4. Research Associate and field coordinator Clark Oman grows crops, applies the products, and sends the produce to labs for residue testing. Once products have met EPA guidelines for safety and efficacy, they are labeled for use.

"We're working on lots of other products for onions and other minor crops that have a track record and minimal environmental impact."