Identification of Factors Involved in Peach Skin Streaking

Project Overview

Project Type: On-Farm Research
Funds awarded in 2017: $15,000.00
Projected End Date: 03/14/2018
Grant Recipient: Clemson University
Region: Southern
State: South Carolina
Principal Investigator:
Guido Schnabel
Clemson University


  • Fruits: peaches, general tree fruits


  • Crop Production: tissue analysis
  • Education and Training: extension
  • Pest Management: integrated pest management
  • Production Systems: general crop production

    Proposal abstract:

    Bright streaks on peach skin of red-blush varieties is a yet undescribed skin discoloration that has been affecting many varieties in the Southeastern U.S. at least since 2003. While symptoms in form of occasional faint streaks are negligible from a consumer acceptance point of view, multiple bright streaks on a fruit clearly suggest damage to the peach skin and will make the fruit unmarketable.

    The cause of streaking is still unknown, but our investigation of historical weather data and assessment of fruit in peach fruit bagging trials prior to harvest showed that peach streaking is associated with long periods of drought followed by a single light rain event. It stands to reason that light rain either directly washes toxins onto the fruit or initiates morning dew that concentrates toxins to damage the fruit skin. Toxins could come from an accumulation of toxins over the growing season on the leaf or fruit surface or from atmospheric pollutants, such as sulfur oxides, nitrogen oxides, ozone, chlorine and chlorine dioxide.

    We have to understand the cause of peach streaking in order to develop management strategies. Our hypothesis is that light rain followed by a period of drought either concentrates directly or generates morning dew that concentrates phytotoxic material onto the fruit skin. Our goal is to identify the substances in raindrops and dew on different surfaces that might damage the fruit.

    Project objectives from proposal:

    -occurrence and severity of streaking in main South Carolina production areas and at the Clemson´s Musser Fruit Research Center

    -identify chemicals in rain water that may cause peach skin streaking from various sites

    -reproduce streaking symptoms under field conditions

    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.