Citrus Tristeza Virus (CTV) testing is complete at the Lindcove Research and Extension Center. Every tree at the Center is tested annually for presence of the virus, and infected trees are removed. This year we are using a new technique for half of our 12,000 trees; a direct tissue blot immunoassay (DTBIA-ELISA) with guidance from Dr. Ray Yokomi at USDA in Parlier. For the remaining trees we are collecting leaf samples for submission to the Central California Tristeza Eradication Agency in Tulare, where testing is performed there using an ELISA technique. CTV is transmitted from tree to tree by phloem-feeding cotton aphids, and has caused losses to California citrus growers when trees are grown on susceptible rootstocks. We remove the infected trees at Lindcove REC in order to protect the citrus research projects and the Citrus Clonal Protection Program Foundation Block trees.