Summary of Awards to Date

Bacterial diseases of tree fruit crops and their control.

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Dec. 1, 2008 - Nov. 30, 2013

Award Number


Funding Agency

Center for Produce Safety


George Sundin, Ph.D.
Michigan State University


Tree fruit crops represent an important agricultural commodity in Michigan, with apple leading in importance, both in terms of acreage grown (44,000 A) and value received by growers ($81.6 million). Cherries are second in importance, with tart and sweet cherries grown on 37,800 acres with a value of $55.5 million. Peaches, plum, and pears are of less importance, and, combined, are grown on 6,200 acres with a value of $14.9 million. The apple acreage in Michigan was reduced approximately 20% between 1997 and 2001 and one of the major diseases responsible for this reduction has been fire blight caused by bacterial pathogen Erwinia amylovora. A severe fire blight epidemic in southwest Michigan in 2000 caused losses exceeding $42 million including losses of approximately 350,000 to 450,000 trees. Fire blight is an exceedingly difficult disease to manage because of several interacting factors: 1) chemical management options such as antibiotics are limited, and are impacted by antibiotic resistance in the pathogen population 2) after the initial blossom phase of the disease, the pathogen is located internally within trees while antibiotic options are surface-associated 3) infection can occur on the scion, reducing yield, and in the rootstock, resulting in tree death 4) most of the popular apple varieties grown in Michigan are highly susceptible to the disease The research proposed in this project is aimed at developing new short-term and long-term disease management measures for fire blight. As such, this work is relevant to three of the five research target areas in the MAES mission. Research on plant disease management contributes directly to Secure Food and Fiber Systems and to Enhancing Profitability in Agriculture and Natural Resources. Furthermore, our research on biological control of fire blight contributes to the Food and Health target area through increasing microbial and chemical food safety.