COMMON NAME: Bacterial Leaf Scorch (BLS) on Oak

SCIENTIFIC NAME: Xylella fastidiosa subsp. multiplex

 

DISEASE DESCRIPTION

Oak is one of five other crops or landscape plants that are susceptible to X. fastidiosa subsp. multiplex.  BLS is a common disease of oaks in Texas, in part due to the climatic extreme of hot and dry spells.

 

SYMPTOMS: Typical symptoms of BLS on oaks include premature browning, or scorching of leaves often accompanied by a yellow border separating the green and brown tissue. As premature leaf abscission occurs the tree will eventually die, usually within 4 – 5 years of the initial appearance of symptoms. BLS usually appears randomly distributed when present in a population of oak trees.

 

BIOLOGY: A variety of oaks including live, southern red, and bur are very susceptible to this disease. This pathogen is primarily spread by insect vectors such as spittlebugs and leafhoppers that also feed on other woody species where the pathogen may be further transmitted. Once introduced the bacteria lives in the xylem, plugging essential tissue carrying water and nutrients.

 

MANAGEMENT METHODS: Proper nutritional and water requirements should be met for oak trees. Correct diagnosis is crucial as bacterial leaf scorch can often be confused with symptoms exhibited by abiotic stresses and oak wilt. Affected branches should be immediately removed and pruning tools sanitized.

 

RESOURCE LINKS:

For pathogen, species affected, alternate hosts, biology, and management methods refer to:

http://www.apsnet.org/publications/apsnetfeatures/Documents/2005/BacterialLeafScorch.pdf

 

For symptoms and management methods refer to:

http://texasforestservice.tamu.edu/uploadedFiles/TFS_Main/Urban_and_Community_Forestry/About_Urban_and_Community_Forestry/Urban_Forest_Information_Sheets/Tree%20Heatlh%20-%20Diseases_BLS.pdf

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This factsheet is authored by Zachary Howard (Masters student)

Factsheet information for the plant health issues represented by the images on the 2019 TPDDL calendar were written by graduate students enrolled in the Department of Plant Pathology & Microbiology PLPA601 Introductory Plant Pathology course in the 2018 Fall semester (course instructor: Dr. David Appel).  This exercise provides an opportunity for a high impact learning activity where the students are tasked with producing an informational output directed to the general public and to provide opportunity for the students to write. 

Photo credits:  John Hartman, University of Kentucky, Bugwood.org