A PSOROSIS-LIKE AGENT PREVALENT IN FLORIDA GRAPEFRUIT GROVES AND BUDWOOD SOURCES

Rio Grande Gummosis (RGG) is one of the most serious diseases of grape fruit in the Indian River region of Florida. Experiments were conducte d to determine if a graft-transmissible agent was associated with this disease in commercial grapefruit, and if any such agent was present i n scion sources used for grapefruit propagation. Indexing data from in dicators revealed that 79% and 31% of the commercial grapefruit and sc ion trees, respectively, contained a psorosis-like agent (PLA). The PL A was present in both RGG-affected and symptomless trees. We conclude that Florida's grapefruit propagation sources are contaminated with a PLA that is now widespread in commercial plantings.