Symptoms of purple top include curled and discolored leaves, axial bud growth resulting in a bushy plant, swollen nodes, and sometimes aerial tubers.
The Columbia Basin Purple Top Phytoplasma (a.k.a. BLTVA).
The purple top phytoplasma lives inside its beet leafhopper insect vector and can infect many plant species including potato, tomato, and various weeds. Early-season transmission is most likely to impact yield and/or crop quality.
Monitor beet leafhopper populations in your area (see below and this page for more details on insect trapping). In areas of high risk, the only clear management strategy is well-timed insecticide applications aimed at migrating beet leafhoppers.