Lettuce infectious yellows virus

Lettuce infectious yellows virus (LIYV) of lettuce, cucurbits, and other vegetable crops was first recognized as a distinct viral pathogen in the Southwestern USA. and Mexico in the early 1980's, associated with increases in populations of sweet potato whitefly.

Symptoms
Leaves show yellowing and/or reddening between veins and stunting of affected plants. Chlorosis of leaves may develop into brittleness.

Lettuce
Compact lettuce heads fail to develop.

Cucurbits
In cucurbits, a splotchy mottle or interveinal chlorosis develops on mature leaves. This may be accompanied by vein-clearing, mild mosaic, subtle curling of the tips of young leaves, and a leathery texture in older leaves. Plants are stunted, exhibit poor fruit set and/or incomplete fruit development. Symptoms may appear as early as 3 weeks after plants emerge or 10-12 days after inoculation.