Incidence of yellows in carrot and lettuce and characterization of mycoplasmalike organism isolates in Oklahoma.

Incidence of yellows was greater in lettuce (Lactuca sativa) than in carrots (Daucus carota) and greater at two eastern Oklahoma sites than at a site in central Oklahoma. Eight isolates of mycoplasmalike organisms were collected from carrots, lettuce, and daisy flebane (Erigeron strigosus). These isolates were seaprated into four groups based on distinctly different symptomatology on aster (Callistephus chinensis). Six of these isolates (two groups) had symptomatology similar to that of aster yellows. Based on the symptomatology on celery (Apium graveolens), these six isolates fit the traditional criteria for aster yellows «Western strains» (...)