Abstract
Budwood was collected from healthy-appearing and Rio-Grande Gummosis (RGG)-affected Ruby Red grapefruit trees from 5 different groves, 13-40 years of age, in the Indian River region of Florida. Similar collections from trees used as scion sources for grapefruit propagation were made at 6 different nurseries. Indexing of the budwood on Madam Vinous sweet orange seedlings under a cool night, warm day temper ature regime resulted in the appearance of oakleaf and mild vein-clearing patterns, indicative of infection with a psorosis-like agent, for 75% and 15% of the budwood from the commercial production and scion groves, respectively. We conclude that some Florida grapefruit budwood sources are contaminated with a psorosis-like agent that has resulted in widespread distribution of the agent in Florida's commercial grapefruit.
