Verticillium wilt first appeared in California lettuce fields in 1995. Since then, researchers have been trying to breed lettuces that would resist the condition - and Agricultural Research Service and University of California-Davis scientists have succeeded in creating the first wilt-resistant parent iceberg lettuce.
A root-rotting fungus called Verticillium dahliae causes verticillium wilt, which causes heads of lettuce to discolor, wilt and die. The fungus can also infect other plants such as strawberries and tomatoes.
The new wilt-resistant iceberg lettuce parent lines are meant to be crossed with consumer-ready lettuces to boost resistance in commercially grown lettuce. Plant breeding companies are already requesting seed samples of the new lettuce, which was made available to researchers and plant breeders in April.