Rickettsia-like bacteria (RLB) were approximately .times. 10 more concentrated in 0.1 M KOH extracts of root sections of peach trees with symptoms of phony disease than in twig sections. RLB also were present in symptomless trees in orchards with 7 and 52% disease incidence. Positive symptoms of phony disease followed within 3-12 mo. of detection of RLB in 8 of 10 initially symptomless trees examined. RLB counts in roots and twigs of peach trees in phony-infected orchards were significantly higher in May than in Feb., Aug. or Nov. RLB also were found in several species of cherry and plum, and in perennial weeds surrounding peach orchards. Positive immunofluorescent tests for RLB were obtained with extracts from Mazzard cherry (P. avium), Shiro plum (interspecific Prunus hybrid) and Johnson grass (Sorghum halepense).