How to Manage Pests
UC Pest Management Guidelines
Early symptoms of turnip mosaic include numerous, small, light green, circular and irregular lesions on leaves. Later symptoms include curvature of the midrib and asymmetrical distortion of the leaf blade. Lettuce infected early may be stunted. The disease is occasionally lethal.
Turnip mosaic susceptibility in lettuce is restricted to crisphead lettuce types with downy mildew progenies derived from P.I. 91532. Transmission is by many species of aphids in a nonpersistent manner. The virus is not seed transmitted. The virus has a wide host range in 20 plant families and is especially common in crucifers.
Crisphead varieties such as Climax, Great Lakes, Merit, or Vanguard are resistant. Butterhead, leaf, or Romaine lettuce types are all resistant.
UC IPM Pest Management Guidelines: Lettuce