Soybean science works in 2,4-D

CENTRAL CASS COUNTY, N.D. -- Farmers who have converted almost entirely to Roundup Ready soybeans and other crops in the past decade soon may have a secondary weapon to gun down glyphosate-resistant weeds and volunteer crops.

Some of them will turn to the old standard 2,4-D, or others to new hormone-based chemistry.

Several companies already are making announcements as they will vie for market position in a technology that is three or four seasons away from commercial production. One is Dairyland Seed Co. Inc. of Wisconsin. The company is one of three regional seed companies that are directly linked as a subsidiary or "seed affiliate" of Dow AgroSciences L.L.C., which owns the patent for 2,4-D herbicide resistance -- one in a general grouping so-called "DHT traits" (for Dow AgrowSciences Herbicide Tolerance).

The hormone herbicide, 2,4-D, was invented in Britain in World War II to kill broadleaf plants (not grassy ones) and was commercialized in 1946. It has moved from an ester-based technology to the amine form, which is less volatile. It has been used less in recent years as farmers have turned to glyphosate, which kills both broadleafs and grassy weeds, but may see a comeback.

2,4-D resistance

Bill Campbell is Dairyland's soybean breeder for the northern region (maturity groups 00, 0 and 1). He's based in Clinton, Wis., but for 25 years, has been commuting to his selection plots from North Dakota to Winnipeg, Manitoba. He's now confident that his company will have 2,4-D-resistant soybean choices for commercial production in 2013 or 2014, pending the technology's "release" by the U.S. Department of Agriculture.

Campbell sees two other related steps.

First, he'll work to "stack" the DHT trait with Roundup Ready traits (R2Y) in varieties available to growers a year later. Monsanto, which had prevented those experimental crosses in the past, has Campbell and others ready to start with those crosses in 2010.

In a related development, Dow plans to release a "complaint-reducing" version of 2,4-D, meaning it will have less odor and movement, says Keith Rekow, based in Langford, S.D., Dairyland district sales representative for North Dakota and South Dakota.

On July 19, Campbell and Rekow led a plot tour in central Cass County, N.D., that also involved Tim Berntson, a grower-distributor from Buffalo, N.D. The tour featured beans that appear in good health despite experimental treatments of four times the normal rate of 2,4-D.

Campbell started with a Dairyland Seed predecessor in 1972, and has continued with the company. He worked in other crops for 12 years and switched to soybeans in 1984.

Creating crosses

A native of Bismarck, N.D., he received his bachelor's degree in horticulture science at North Dakota State University in Fargo and then went on for a master's degree in plant breeding from the University of Minnesota in St. Paul.

Campbell describes his soybean breeding program as a "distributed" breeding program, meaning it is distributed into the multiple environments it eventually will be grown in commercialized. He compares it to other programs that are more centralized. His test plots are in six places as far north as Winnipeg.

Campbell makes 1,200 new "family" crosses per year. In two years, he gets it down to 40 or 50 of the most elite families. Winter plots are in Puerto Rico and Florida, and do yield testing in Argentina and Chile.

"If I were to cross domestically in the summertime, I can yield-test here next year, so this can be super-fast," he says, noting that's standard in the industry.

Each of his locations for distributed breeding will have 5,000 to 8,000 new lines. Each year, he saves about 8 percent. They throw out about 92 percent per cycle, based on a combination of visual and actual yield evaluation from five-foot wide "micro-combines."

"I don't fear the dumpster," he says, chuckling, and acknowledging that he'll never know whether some very good material may have been discarded.

Campbell likes to do early-generation yield-testing from F2 seed, meaning they're two generations foundation seedstock. (F0 is the year of the cross in a summer; and F1 is hybrid planted in the southern nursery.) The beans in the Cass County plot tour are F4s, he says.

Job well done

Among other things, he says Dairyland prides itself on resistance to phytophthora root rot.

"I'm a combine breeder," he says, noting that he only keeps the varieties that do well in the field, and doesn't sort it out until later whether the yield improvement comes from a variety of reasons -- phytophthora root rot, cyst nematodes or iron deficiency chlorosis, among them.

"You don't test for the trait first, you test for the yield, and more often than not you bring the good traits along," he says. "I believe what the combine tells you. Let the combine select for morphological issues, or phytophthora," Campbell says.

The scientist recalls his delight in seeing Dow's 2,4-D soybean trait in action to his first time seeing the Roundup Ready effect. "You could see effects in an hour, and in three hours you could see that they were going to croak -- velvetleaf halfway twisted to the ground."

Rekow notes that for the past two years, Campbell's varieties have shown the top yields at trials at the NDSU Research and Extension station in Carrington. One of them was more than 74 bushels per acre, which at the time was a record for soybeans at any of the stations. He's had similar results on trials near Crookston and Fosston, Minn.

Rekow notes that in trials in especially heavy Fargo clays in Durbin, N.D., some competing varieties that were hit with phytophthora root rot in 2008 and took 40 to 60 percent hits on stands, while the Dairyland varieties lost only 10 to 15 percent.