A bothersome plant virus first discovered in 2006 in the Salinas Valley of California was discovered last season near Tacna, Ariz., a farming community east of Yuma, and in five different fields in California's Imperial Valley.
The disease is like others in lettuce that cause decay and render the crop unmarketable, except that it is not caused by a soil-borne pathogen but vectored by a common insect.
Impatiens necrotic spot virus, or INSV for short, can resemble burn damage caused by chemical applications, according to Steven Koike, a plant pathologist and director of TriCal Diagnostics in Hollister, Calif. Koike was a farm advisor with the University of California when the disease was first discovered in California.
By itself, INSV in lettuce does not cause wilting, root rot or discoloration, crown rot or vascular discoloration, according to Koike. In combination with other pathogens, a confusing combination of symptoms can arise, necessitating lab tests to determine the cause.
At the end of the day INSV does the same thing to lettuce that other plant viruses do – it renders the crop unmarketable. Symptoms can vary depending on when the plant was infected, the type of lettuce involved, and the environmental conditions, he said.
Read the complete article at Farm Progress