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Dodder Transmission of a Mycoplasma from Ash Witches’-Broom. C. R. Hibben, Kitchawan Research Laboratory of the Brooklyn Botanic Garden, Ossining, New York 10562; B. Wolanski, Boyce Thompson Institute for Plant Research, Yonkers, New York 10701. Phytopathology 61:151-156. Accepted for publication 4 September 1970. DOI: 10.1094/Phyto-61-151.

An infectious agent was transmitted from witches’-broom of declining Fraxinus americana to Vinca rosea by means of dodder. Symptoms in V. rosea were typical of yellows-type infection. Transmissibility was confirmed by graftage between infected and healthy V. rosea, and by dodder transmission of the agent from yellowed V. rosea to Daucus carota. Attempts at transmission from sap of yellowed leaves and dodder did not reveal a mechanically-transmissible disease agent. Thin sections of midveins and petioles from yellowed F. americana, V. rosea, and D. carota; of roots from yellowed F. americana and V. rosea; and of dodder strands that had been parasitizing yellowed V. rosea, were examined by electron microscopy. Typical mycoplasmalike bodies were present, often in large numbers, in the phloem cells of all four species. These bodies were indistinguishable morphologically from mycoplasmas known to cause yellows-type diseases. No virus particles were observed either in the phloem and xylem elements, or in the parenchymatous cells of yellowed leaf tissue. From these results, a mycoplasma etiology is suspected for the witches’-broom disease of ash.