A virus that poses a serious threat to the Louisiana tomato industry was identified in a Plaquemines Parish field the first week in April, according to experts at the LSU AgCenter.

“We had hoped that tomato yellow leaf curl virus might not show up this year or at least wait until the late summer,” said Ken Whitam, LSU AgCenter plant specialist. “But that's not the case.” Whitam and others had warned a few weeks ago that the leaf curl virus might be a problem for Louisiana tomato growers this year.

The virus, which moved from Europe through the Dominican Republic and on to Florida, made a few appearances in Louisiana's commercial tomato production fields and greenhouses last year, but the problems were limited and there didn't seem to be an effect on home gardeners.

Now officials warn it is a serious threat to commercial growers and home gardeners if it spreads across the state.

“This virus presents a serious threat to the commercial tomato industry in South Louisiana — the creole tomato industry — and to those in other parts of the state if it should spread,” Whitam said.

A plant sample from Plaquemines Parish was identified as being positive for tomato yellow leaf curl virus after testing this week by Rodrigo Valverde, an associate professor in the LSU AgCenter's department of plant pathology and crop physiology.

Whitam said the virus is transmitted by white flies, and “a half-dozen white files can infect an entire field in a week. When you see it, it's too late.”

Controlling the disease is nearly impossible. “Once it is identified, usually the entire field is infected.”

That means eliminating the carriers of the disease before problems develop is the only way to keep it from spreading, he said. “Controlling white flies before, I repeat, before the disease is established is the only way to avoid the problem.”

Symptoms of the disease include yellowing of the plants with “bunchy” growth — called a rosette appearance. The leaf tips also round off and curl upwards. In addition, the infected plants don't produce fruit.

The virus moved from Europe to the Dominican Republic in short time, Whitam said. It was reported in Florida in 1998 and was first identified in Louisiana in 2000. “If it continues on its rapid journey, it should cover the state this year,” Whitam warned.


Rick Bogren writes for the LSU AgCenter. rbogren@agctr.lsu.edu.