Oct 17, 2008

IR-4 Continues to Generate Herbicide Registration Data

Registering an herbicide for use on a specialty crop is a long, involved process.

A federally funded program, the Interregional Research Project Number 4 (IR-4), has been shepherding that process since 1963. IR-4’s mission is to develop and submit regulatory data to EPA to support the registration of pest control products for specialty crops.

IR-4 is headquartered at Rutgers University in New Jersey. Four other universities house regional IR-4 offices: Cornell University, Michigan State University, the University of Florida and the University of California, Davis.

Dan Kunkel, IR-4’s associate director, manages the pesticide registration process for specialty food crops. He illustrated the typical registration process for an herbicide:

A representative, usually a university or Extension researcher, will approach IR-4 on behalf of a group of growers. The growers – let’s say they grow carrots – are looking for a way to control weeds without damaging their crop. They want to take an herbicide already on the market – let’s call it Deathblow (which is not a real herbicide) – and adapt it for use on carrots. Deathblow works well on, say, soybeans, so they figure it has potential on carrots. In order to achieve their goal, however, they need to generate data that will not only prove Deathblow can work on carrots, but that it can work profitably. Cooperation from the chemical company that manufactures Deathblow is essential.

“It’s not in (the company’s) economic interest to generate data on these uses in the first place, but we can do that to help the carrot growers out,” Kunkel said.

Kunkel’s program gets about 200 pesticide registration requests each year. A workshop is held every fall to bring all stakeholders (IR-4, pesticide manufacturers, university researchers, growers) together and whittle down the list of requests to the 85 or so the program can support each year. After that, Kunkel and his team know what they need to focus on.

Let’s assume Deathblow was approved for further study. Before any data can be generated on the herbicide, the exact goal of its registration and the wording of its eventual label on carrots need to be figured out. What is the problem weed? How will the herbicide neutralize it? IR-4 communicates back and forth with other stakeholders to answer those questions. It can take six months to a year to complete those discussions and develop a registration protocol, Kunkel said.

Once the protocol is approved, which usually happens in January or February, IR-4 has until the following October to conduct research trials and generate data. To get a national registration for Deathblow on carrots, field trials would need to be conducted at research centers in the mid-Atlantic, the Midwest, Florida, Texas, California and the Pacific Northwest. The central IR-4 office would work with its regional offices to make sure the trials fit the parameters of the proposed label. IR-4 personnel would conduct the trials, he said.

Once the trials are complete, the results are sent to an analytical laboratory to determine if or how much Deathblow residue is remaining on the carrots. About a year later, IR-4 submits a data summary and petition to EPA, which takes about 15 months to review the request. If EPA determines Deathblow is safe on carrots, the registration becomes official, Kunkel said.

EPA’s Office of Pesticide Programs approves about 98 percent of IR-4’s requests annually (IR-4 requests make up about half the office’s approvals). Maybe one or two requests per year fail to get approval, he said.

Herbicide decline

In the early to mid-1990s, herbicide registrations made up nearly 45 percent of IR-4’s pesticide projects for fruit and vegetables. In 2005, that number had shrunk to about 30 percent, according to a paper Kunkel co-wrote, “The Role of IR-4 in the Herbicide Registration Process for Specialty Food Crops.”

The paper cited three main factors that have contributed to the decline in herbicide registrations: fewer herbicides available, product liability concerns and the increased focus of pesticide manufacturers on developing new, safer and reduced-risk insecticides and fungicides.

“It has been a number of years since a new herbicide has been developed for a major crop that could be extended to specialty food crops,” according to the paper, which was published in the April-June 2008 issue of Weed Technology.

There’s been a dearth of good herbicides in the specialty crop market for a long time, largely due to crop sensitivity. Herbicides developed for corn and soybeans can damage crops like carrots or lettuce, Kunkel said.

The unwillingness of herbicide manufacturers to expend resources on small, sensitive specialty crops has forced weed scientists to get creative with the herbicide chemistries that are available, many of which have been on the market for decades. Trying to apply such chemistries to specialty crops, however, can be like “trying to pound a square peg into a round hole,” he said.

Developments like Roundup Ready crops have added to the problem, and new herbicides designed specifically for commodity crops are even more difficult to adapt to specialty crop usage, Kunkel said.

Growers have dealt with the dearth of herbicides by cultivating weeds with tractors or hand labor, but these techniques are expensive (thanks to labor and fuel costs), time consuming and can injure the crop, he said.

To combat the shortage, Kunkel would like to see other tools utilized, such as plants bred for herbicide tolerance – bringing the crop to the chemical instead of the chemical to the crop.

Doing that would require more cooperation between weed scientists and plant breeders, as well as chemical manufacturers, he said.