Fish extracts for integrated disease, insect and fertility management in organic blueberries

Project Overview

Project Type: Research and Education
Funds awarded in 2009: $119,000.00
Projected End Date: 12/31/2011
Region: Southern
State: Georgia
Principal Investigator:
Harald Scherm
University of Georgia

Annual Reports


  • Fruits: berries (blueberries)


  • Crop Production: foliar feeding, organic fertilizers, tissue analysis
  • Education and Training: demonstration, extension, on-farm/ranch research
  • Pest Management: biorational pesticides, botanical pesticides, integrated pest management
  • Production Systems: transitioning to organic

    Proposal abstract:

    The purpose of this project is to develop an integrated system for disease, insect, and nutrient management in organic blueberries centered around foliar applications of extracts made from fish byproducts, a renewable resource. Blueberry is now the most important fruit crop in Georgia, and the organic blueberry acreage is expanding rapidly in the sate as well as in neighboring Florida and North Carolina. However, fertility and pest management options for organic blueberries are currently very limited. For example, organic growers lack the tools and research-based information to manage foliar diseases such as Septoria leaf spot, Gloeosporium leaf spot, Phyllosticta leaf spot, and leaf rust. Epidemics of these diseases lead to premature defoliation in summer and fall, reduced flower bud set during fall and winter, and lower return yields and weaker plant growth the next year. Fish extracts have been used successfully to manage foliar diseases in other crops, and in a recent field trial with a number or organic fungicides, two OMRI-approved fish extracts provided substantial control of Septoria leaf spot. Thus, our primary objective is to compare and demonstrate the efficacy of a broader range of such products against the leaf disease complex on organic blueberries. During the summer, at the same time when foliar diseases need to be managed, the blueberry leaf beetle has become a major pest on young organic blueberries in Georgia and Florida. Weedy fields can have especially serious problems with this pest, and several months of young growth can be destroyed in a few days. Previous studies on other perennial crops have shown that fish extracts can have powerful repellent, antifeedant, and/or insecticidal activity against insects and mites Thus, our second objective is to evaluate leaf beetle suppression following application of fish extracts. Fertility management is one of the most problematic areas in organic blueberries. Fish extracts, applied as a spray during the summer to manage foliar diseases, may have significant added value by providing readily available macro- and micro-nutrients, including phosphorus, to support plant growth and development during this critical period. These nutritional benefits will be assessed in our project by measuring foliar nutrient status, plant growth, flower bud set, and return yield the following year in fish extract-treated plots.

    Project objectives from proposal:

    The overall aim of this project is to develop an integrated approach for improved disease, insect, and nutrient management in organic blueberries during the summer and fall, centered around foliar applications of fish extracts. Specific objectives are to:
    1) compare and demonstrate the efficacy of several fish byproducts against foliar diseases of blueberry in a certified organic planting,
    2) evaluate blueberry leaf beetle suppression in fish extract-treated plots, and
    3) determine the nutritional benefits of fish extracts applications by measuring foliar nutrient status, plant growth, flower bud set, and return yield in treated plots.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.