University of California

Fruit Physiological Disorders


Stonefruit: Skin Discoloration

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Skin Discoloration. Stonefruit, Peach
Skin Discoloration. Stonefruit, Peach
Occurence
Peach and nectarine fruits.

Importance
It has become a frequent problem in the last decade in California, Washington, Georgia, South Carolina, New Jersey, and Colorado, as well as in other production areas in the world such as Italy, New Zealand, Australia, Argentina, and Chile.

Symptoms
Skin discoloration (SD) symptoms appear as brown and black spots or stripes that are restricted to the skin.

Causes
Abrasion damage in combination with heavy metal comtamination are required for SD development. The damaged skin cells, where the anthocyanin/phenolic pigments are located, collapse and their contents react with heavy metals turning their color dark brown/black. Iron, copper and aluminum are the most deleterious contaminants. Only 5-10 ppm iron is enough to induce SD at the physiological fruit pH (~ 3.5). This contamination can occur within 15-20 days before harvest, during harvesting or at packing operations. Foliar nutrient, fungicide and insecticide preharvest sprays which contain the above-mentioned metals in combiantion with abrasion damage have the capacity to induce SD on peach and nectarine fruit when sprayed close to harvest.

Control:

Reduce fruit abrasion damage

  • Treat fruit gently.
  • Avoid long hauling.
  • Keep picking containers dirt free.

Reduce contamination of fruit.

  • Keep harvesting equipment clean.
  • Avoid dust contamination on fruits.
  • Check your water quality for contamination with metals (Fe, Cu & Al).
  • Do not spray foliar nutrients containing Fe, Cu, or Al during fruit maturation.
  • Stop preharvest applications of the following fungicides and foliar nutrients at the indicated days before harvest:
Chemical Days before harvest
Z.I.P.® 20
Benlate® 12
Rovral® 7
Funginex® 3
Ronilan® 1


In case of a possible SD high incidence situation with peach and/or nectarine, delay packaging for 48 hours to detect fruit SD damage during the grading operation.

As a long term solution, it is suggested that chemical manufacturers attempt to identify and remove the possible sources of contamination from their products that may cause SD before distributing them.

References
Cheng, G. W. and C. H. Crisosto. 1994. Development of dark discoloration on peach and nectarine (Prunus persica L. Batsch) fruit in response to exogenous contamination. J. Amer. Soc. Hort. Sci. 119:529-533.

Crisosto, C. H., R. S. Johnson, J. Luza, and K. Day. 1993. Incidence of physical damage on peach and nectarine skin discoloration development: anatomical studies. J. Amer. Soc. Hort. Sci. 118:796-800.

Date

1994 & 1993

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How to Cite

Author(s) names. Initial publication or update date (located at the bottom). Title. Link to the specific Fruit Physiological Disorders webpage (Accessed date)

Example: Mitchell, F. G., G. Mayer, and A. A. Kader. 1980. Injuries cause deterioration of sweet cherries. California Agiculture 34(3):14-15.

http://ucanr.edu/sites/Postharvest_Technology_Center_/Commodity_Resources/Fruit_Physiological_Disorders/?uid=20&ds=822 (Accessed January 18, 2014).

College of Agricultural & Environmental Sciences
Postharvest Technology Center
Department of Plant Sciences

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