Identification of Factors Involved in Peach Skin Streaking

View the project final report

Commodities

• Fruits: peaches, general tree fruits

Practices

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

Streaking is a skin discoloration in red blush varieties of peaches, characterized by club-shaped streaks, lacking red color. Symptoms vary in intensity ranging from faint light streaks to pronounced streaks and necrotic tissue. The current hypothesis suggests that causal agents are accumulated in the atmosphere during periods of drought and then brought down with light rain events. Occurrence and severity data were obtained from a commercial orchard and Clemson´s Musser Fruit Research Center in the 2017 growing season. Trees were examined for streaking symptoms starting four weeks prior to harvest in weekly intervals. On Julyprince (Clemson) 50% of fruit examined showed symptoms, while on Scarletprince (Commercial grower) 6 to 25% of fruit examined displayed streaks. Incidence was also recorded with relation to fruit positioning within the canopy (top, bottom, inside, outside) which for Julyprince was 43%, 59%, 27%, 27% respectively. Data from one location with Scarletprince suggested a greater incidence on fruit on the top and outside. Precipitation and pH of rain water were collected for twelve locations at the commercial orchard for six varieties with ripening periods between mid-June and mid-August. Both precipitation and pH differed greatly between sampling dates and locations. Rain samples were analyzed for total and free chlorine as well as chlorine dioxide. Although levels of free chlorine and chlorine dioxide were not within the detectable range of 0.01-6 mg/L for Cl₂ and 0.05-11mg/L for ClO₂, more work needs to be done to determine their concentrations at the time of precipitation. Acidic and ozonated solutions were applied to Cresthaven and August Lady prior to harvest but none of the treatments reproduced the symptoms.

-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