Texas Plant Disease Diagnostic Lab
COMMON NAME: Bacterial Leaf Scorch of Blueberry
SCIENTIFIC NAME: Xylella fastidiosa subsp. multiplex [1]
DISEASE DESCRIPTION
Bacterial leaf scorch (BLS) of blueberry is one of the more recently described of the five different diseases of landscape and crop plants caused by the bacterium Xylella fastidiosa and covered in this series.
SYMPTOMS:
Symptoms of infection are necrosis of leaves, a burnt edge of older leaves, stem yellowing, and dieback[2]. These symptoms are typical of all of the Xylella scorch infections of plants. New shoots are very thin and have reduced number of flower buds. Leaf drop and loss of new roots eventually occurs before death of the plant. Complete plant death can occur up two years after initial identification of symptoms [3, 4]. The appearance of the yellow stems can be used to rule out other abiotic or biotic factors when diagnosing the presence of X. fastidiosa subsp. multiplex because this symptom has been seen across all plants tested for bacterial leaf scorch of blueberries [4].
BIOLOGY:
X. fastidiosa subsp. multiplex is transmitted by xylem feeding insect vectors such as bluegreen and glassywinged sharphooters, and spittle bugs. The bacteria can also be spread through propogation with infected plant tissue. The bacteria inhabit the xylem where it attaches to cell walls and multiplies thus forming a biofilm that blocks that flow of water to the plant. The result is the scorched or burnt symptom seen in leaves infected with X. fastidiosa subsp. multiplex.
MANAGEMENT METHODS:
The development of controls for BLS of blueberries by Xylella fastidiosa subsp. multiplex is ongoing. However, there have been multiple suggestions on how to manage the disease in blueberry crops. The quarantine of plants from infected areas is highly suggested. New plants should not be planted if received from infected areas. Insect vectors can be monitored and controlled through the use of insecticides. Also pruning and removal of infected plant material using sanitized pruning tools is an effective method for managing the bacterial disease. Some varieties of blueberries have shown some or complete resistance to the bacteria. If possible, controlling plant stressors can also help slow the disease progression although it may not cure the disease. The plant may continue to produce fruit at lower yields until the plant completely dies.
RESOURCE LINKS:
University of Georgia Extension Service
Comprehensive resource for bacterial leaf scorch in blueberries. Xylella fastidiosa subsp. Multiplex has been severe for the Georgia blueberry industry. The site provides information on the causal organism, disease cycle, symptoms, cultural and chemical controls and research references.
Cooperative Extension System
https://articles.extension.org/pages/29628/bacterial-leaf-scorch-of-blueberry
Similar to the information in the University of Georgia Extension website. Covers the management techniques and the symptoms of the bacterial disease.
Plant Health Australia
Provides a short informational bulletin about the glassy winged sharpshooter and how to identify the primary insect vector that spreads Xylella Fastidiosa subsp. Multiplex.
LITERATURE CITED:
- Lisa M. Overall, E.J.R., Insect Vectors and Current Management Strategies for Diseases Caused by Xylella fastidiosa in the Southern United States. Journal of Integrated PestManagement 2017. 8(1): p. 1-12.
- Holland, R.M., et al., Distribution of Xylella fastidiosa in Blueberry Stem and Root Sections in Relation to Disease Severity in the Field. Plant Disease, 2014. 98(4): p. 443-447.
- Chang, C.J., et al., Bacterial Leaf Scorch, a New Blueberry Disease Caused by Xylella fastidiosa. Hortscience, 2009. 44(2): p. 413-417.
- Mary Helen Ferguson, C.A.C., Barbara J. Smith, Association of Xylella fastidiosa with Yield Loss and Altered Fruit Quality in a Naturally Infected Rabbiteye Blueberry Orchard. HORTSCIENCE 2017. 52(8): p. 1073-1079.
This factsheet is authored by Lia Murty (PhD PLPM)
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.