Before TYLCV-DNA probes became available, selection for
TYLCV resistance was based on the absence (or attenuation) of
symptoms in infested fields and in amelioration of yields. Today,
we realize that all tomato cultivars and lines currently available
are, at best, tolerant to TYLCV; although yields and symptoms
have much improved compared with susceptible cultivars, plants
contain various concentrations of virus (12).