Sustainable Management of Fire Blight in Apples using Plant Growth Regulators and Plant Defense Activators

View the project final report

Commodities

• Fruits: apples

Practices

• Pest Management: biorational pesticides, chemical control, cultural control, integrated pest management

1. Problem, Novel Approach and Justification.

Fire blight, caused by the bacterial pathogen Erwinia amylovora, is one of the most devastating diseases of apple worldwide, capable of destroying entire orchards in unforeseen epidemics, and costing farmers millions of dollars in management and damage in the United States annually. Presently, management relies almost exclusively on antibiotic application, which have come under public scrutiny due to the potential for antibiotic resistance development bacterial populations. We will optimize alternative management programs including plant growth regulators, plant defense activators, and biological protectants, materials that have performed well in preliminary testing in research orchards.

2. Hypothesis and Research Plan.
We hypothesize that the novel fire blight management programs tested here, including prohexadione calcium, plant defense activators, and biological products, can be used in an integrate manner to provide both economical and horticulturally sustainable management of fire blight. Specifically, we believe that prohexadione calcium applied pre-bloom at low doses can provide disease control by thickening cell walls, creating a physical barrier to pathogen entry, without reducing tree vigor. Biological materials may provide additional protection by inhibiting and/or outcompeting the pathogen at the point of primary infection. Plant defense activators prime host defenses, making them less susceptible to infection. We will optimize the efficacy of this management paradigm in two productions for maximum disease control and minimum impact on tree productivity.

3. Outreach Plan.
Results will be communicated to our stakeholder audience through well-established channels, relied heavily upon by apple growers in the region for orchard recommendations. Presentations will be given at regional industry and extension meetings such as the New York and Vermont Fruit Schools held annually in February. Findings will be reported in articles in industry publications such as the NY Fruit Quarterly, peer reviewed journals such as Plant Disease, and seasonally-relevant extension publications such as Scaffolds. Perhaps most importantly, information will be conveyed through extension outlets, such as direct conversations between extension educators and farmers, and real-time management recommendations in seasonal newsletter such as Eastern NY ‘E-alerts’, Western NY ‘Fruit Fax’, and VT apple management update emails.

The objective of this work is to optimize use of the plant growth regulator, prohexadione calcium, natural plant defense activators, and biological antimicrobials to manage the bacterial disease fire blight (Erwinia amylovora) expressing both as blossom and shoot blight, without the use of antibiotics or compromising tree productivity. To achieve transition to practice, trials demonstrating both disease management and unhindered tree performance will be needed for regionally important cultivars.