SYMPTOMATOLOGY AND HISTOPATHOLOGY OF FIBROUS ROOTS OF ROUGH LEMON(CITRUS LIMON) INFECTED WITH FUSARIUM-SOLANI

Fibrous-root decay and epidermal and cortical sloughing were common on blight trees in two citrus groves with severe symptoms in October 1975. These symptoms were present to varying extent on blight trees in other groves, and some fibrous-root decline also was present on apparently healthy trees. Fusarium solani was present in declining fibrous roots of diseased and healthy trees and occurrence appeared to be limited to the fibrous roots. Fusarium infection resulted in early cortical degeneration, leaving epidermal sleeves on intact, infected steles. Generally, in the xylem and cortex with advanced symptoms, only chlamydospores were present. Sites of early infection conained abundant hyphae and immature chlamydospores. Hyphae penetrated the cortex intracellularly and intercellularly, and all cell types of the xylem appeared to be infected predominantly through pits. Fusarium was found on the surface of the epidermis and in broken epidermal cells of healthy-appearing and diseased roots. © 1978 Kluwer Academic Publishers.