Wind scar and oil spotting: two blemishes you can plan around
Much of the fruit lost to class downgrades is marked by the wind in spring or by handling at harvest. Both follow patterns growers can act on.
Wind scar happens early
Wind scar forms almost exclusively within twelve weeks of petal fall.1 Young fruit are most sensitive to rubbing by older leaves in the first eight weeks, with lighter damage from week nine to twelve and little afterwards.2 Citrus Australia puts the share at 95 percent of significant damage within those twelve weeks, mainly from the hard edges of old leaves.3
The cost is large. Florida packinghouses commonly eliminate 15 to 30 percent of fruit because of wind scar, and in Australia the share of fruit downgraded for wind blemish ranges from 10 percent to 50 percent depending on the year.2,3 Wind speeds above about 25 km/h are enough to cause scarring.1
Windbreaks pay back in packout
In a Florida trial, trees protected by artificial windbreaks packed out 53 percent top-grade fruit against 30 percent for exposed trees, and also yielded 17 percent more fruit by number per unit of canopy.1 An Australian study cited by Citrus Australia found 67 percent Class 1 fruit in protected blocks and 40 percent in unprotected ones.3 Poor pruning that leaves dead wood and long, thin fruiting branches increases blemish.3
Oil spotting is a turgor problem
Oleocellosis is the rupture of oil glands in the peel by impact or rough handling. It happens more easily when the peel is turgid, which is why harvest and handling may need to be delayed after irrigation or rain.4 For US No. 1 oranges, oil spots count as a defect when they are depressed or soft, or when their aggregate area exceeds 5 percent of the surface.5 Postharvest pitting is a different disorder, caused by warm storage of waxed fruit and showing three to seven days after packing.6
In mandarins, rind breakdown is weather-driven too: it appears when rain coincides with a sudden drop in temperature, and it is worse on fruit on the outside of the canopy.7
What this means in the orchard
Scout for wind marks in the twelve weeks after petal fall, when it can still guide windbreak and pruning decisions. Before picking, check rain and irrigation timing. Recording defects per block, week by week, shows whether a problem is spring wind, handling or weather.
Sources
- Freeman B. (1976). Artificial windbreaks and the reduction of windscar of citrus. Proc. Fla. State Hort. Soc. 89:52–54. PDF
- Albrigo L.G. (1976). Influence of prevailing winds and hedging on citrus fruit wind scar. Proc. Fla. State Hort. Soc. 89:55–59. PDF
- Citrus Australia. Windbreaks for Citrus (fact sheet). PDF
- Habibi F., Sarkhosh A., Ritenour M.A., Brecht J.K. (2025). Postharvest physiological disorders of blood orange fruit (HS1501). UF/IFAS EDIS. doi
- USDA AMS (1999). United States Standards for Grades of Oranges (California and Arizona). PDF
- Wardowski W.F., Petracek P.D., Grierson W. (1997). Oil spotting (oleocellosis) of citrus fruit, Circular 410. UF/IFAS. PDF
- Fake C., Pilz S. (2010). Mandarin Fruit Quality. UC Cooperative Extension. PDF