Virus has Gotten Past Resistant Gene

By Patrick Cavanaugh, Editor

Tomato spotted wilt virus is becoming big in the central San Joaquin Valley, according to Tom Turini, University of California Cooperative Extension Farm Advisor in Fresno County for vegetable crops. The virus had earlier been spotted in lettuce, and this has caused some concern in this season’s tomato crop.

Tom Turini

“We had some concerns early in the season that we might be looking at a year where it’ll become a challenge, because we were finding it in lettuce back in February and March in the Huron area,” Turini said. “And then we notice that tomatoes were showing the virus symptoms. We had been managing tomato spotted wilt in processing and fresh market tomatoes largely with a resistance gene, and it seemed that the resistance was breaking.”

The virus is spread by thrips, and the gene in the tomato was the biggest deterrent in combating thrips.

“We were also talking about an IPM program, but the industry was leaning on this gene. This gene became a big part of their spotted wilt prevention program,” Turini said. “While sanitation of weeds was practiced, and there was some thrips management, it was really dependent upon this single gene resistance in the tomatoes, and as of 2016, we saw evidence that that gene was no longer performing.”

Because the virus can wipe out entire tomato fields, researchers are scrambling to find a new way to deter the thrip spreading the virus on tomatoes.