Skip to main content

Mycoplasmalike Organism Found in the Phloem of Bunch-Diseased Walnuts

Buy Article:

$29.50 plus tax (Refund Policy)


Walnut bunch is a yellows-type of witches'-broom disease occurring on Japanese, Manchurian, English, native black walnut, and butternut. An electron-microscope study of the phloem tissues of walnut revealed the presence of a mycoplasmalike organism (MLO) in diseased but not in healthy leaf and stem phloem cells. The MLO are pleomorphic, vary in length from 150 to 1000 nm, and are enclosed in a plastic trilaminar unit membrane. Spherical or oval shapes predominate, but tubular forms were also evident near sieve plates. Some sections clearly showed the presence of ribosome- and DNA-like material within MLO cells. The apparent absence of virus particles, together with the consistent association of MLO in diseased but not in healthy walnuts, suggests MLO as a likely causal suspect. The possible relationship of walnut bunch and pecan bunch disease is discussed. Forest Sci. 22:144-148.

Keywords: J. cinerea; J. mandshurica; J. regia; J. sieboldiana; Juglans nigra; Walnut bunch; brooms; electron microscope

Document Type: Journal Article

Affiliations: Principal Plant Pathologist, USDA Forest Service, Northeastern Forest Experiment Station, Delaware, Ohio

Publication date: June 1, 1976

More about this publication?
  • Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
    Forest Science is published bimonthly in February, April, June, August, October, and December.

    2015 Impact Factor: 1.702
    Ranking: 16 of 66 in forestry

    Also published by SAF:
    Journal of Forestry
    Other SAF Publications
  • Submit a Paper
  • Membership Information
  • Author Guidelines
  • Ingenta Connect is not responsible for the content or availability of external websites

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more