Aphid tracker gives growers of legumes fighting chance

MOSCOW, Idaho – The aphid tracker, as it’s called, reports on the number of aphids coming into the area in the spring and whether they are infected with viruses that are capable of causing huge losses in legume crops.

A University of Idaho entomologist has developed a website to help growers of dry peas and lentils determine when to treat crops for plant viruses carried by pea aphids.

“Viruses can cause severe yield loss – at least a 30 percent yield loss and sometimes more depending on conditions,” said Sanford Eigenbrode, who heads the aphid tracker project.

“So that’s a fairly big hit for the producer. It can eliminate the profit they can make from these legumes, which don’t have a big profit margin anyway. So it’s destructive and it’s a big concern of growers.”

Eigenbrode started his project three years ago with grant funding from the U.S. Department of Agriculture and local grower associations.

“What we have been doing since 2009 in a most dedicated way is putting out traps across the whole region that catch aphids when those aphids are arriving throughout the weeks during the establishment of the legume crops,” Eigenbrode said.

The insects are tested for viruses using a molecular tool that can detect either of two viruses that are the most threatening to the crops.

Eigenbrode then reports those findings on the aphid tracker website. Follow-up tests and crop samples are also reported on the website, which includes maps of specific areas where the infected aphids were found.

This information is posted year-by-year so growers can see the cumulative results.

That’s important, because major infestations of virus-infected aphids usually show up about every seven to 10 years. The last major virus attack in the Moscow area happened in 2005.

Todd Scholz of the USA Dry Pea and Lentil Council in Moscow said that year growers lost 20 to 90 percent of their legume crops because of viruses carried by aphids.

“So it’s a big impact. This project averted a disaster last year. We did get notification that people took action” after being warned of virus-infected aphids on the aphid tracker website, Scholz said.

Despite the proven benefits, however, the growers association has not yet committed to continuing funding, Scholz said.

“The research committee didn’t think it was that critical,” Scholz said. “Their personal plan was, they sprayed every year to protect against aphids. They didn’t see the need for the project.”

Scholz said he personally supports the project and hopes the growers association will continue financial support.

“In our region we’ve only had (a significant virus infection) three or four times,” Scholz said. “We haven’t lived through a major aphid virus attack – we had minor ones, although we had a serious one five years ago.

“My concern is, we’ve got a lot invested in this, and we’ve got to figure out how to maintain it so when we do have that impact we will be able to react to it. Early warning is the best way to protect the crop.”

Scholz said the second concern about continuing to fund the project is to reduce the amount of pesticides used on legume crops.

The current broad-spectrum pesticide commonly used by farmers lasts for about 30 days and kills aphids and everything else.

Scholz said that under the 1996 Food Quality Protection Act, the Environmental Protection Agency is encouraging growers to move away from such potent chemicals.

“So one of the ways you do keep that tool, you predict when it’s most needed so you can reduce the amount of application you use,” Scholz said.

This method is currently in use among fruit tree growers who use traps to determine when pests are flying in so they can cut down on the number of pesticide applications and control the pests better.

“Sanford is trying to give us a tool that better tells us when we should spray,” Scholz said. “It’s an excellent project and gave us very useful information. But it’s hard to use and expensive, so that’s the issue. I think it’s one of the most useful research projects we have supported, but it’s hard to show growers that there’s a payoff.”