Technical Abstract: Two crinivirus species infect Tomato (Lycopersicon esculentum): Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV). Recent studies demonstrated that transmission efficiency and persistence of ToCV in the vector varies significantly among the 4 vectors capable of transmitting ToCV. Trialeurodes abutilonea and Bemisia tabaci biotype B are highly efficient vectors of ToCV. B. tabaci biotype A and T. vaporariorum are less efficient vectors. The complete nucleotide sequence of the bipartite genome of ToCV was sequenced and compared with related crinivirus species. RNA 1 is organized into four open reading frames (ORFs), and encodes proteins involved in replication, and RNA 2 encodes nine ORFs including genes that encode a HSP70 homolog and two proteins involved in encapsidation of viral RNA. Two forms of resistance have been identified that reduce the impact of criniviruses on tomato. Acylsugar production on foliar trichomes reduces vector feeding and can slow the rate of TICV transmission under field conditions. Resistance to TICV infection was recently discovered in a wild species and studies are in progress to determine the efficacy of moving this resistance into cultivated tomato.