
What you see: Rough brown patches on the surface of your avocado. They may look a little geometric, possibly like scales.
What it is: Windblown leaves and branches damaged the avocado while it was a tiny “baby.” The avocado patched up the injury, but the repair job cracked and regrew as the avocado enlarged.
Eat or toss: Eat. These avocados may not look perfect, but they should still be fine to eat.
Fully grown avocados with these types of rough brown patches on their skin are still edible
Corky brown areas on an avocado’s exterior usually indicate a healed injury. When the brown patches look vaguely angular, almost like scales, and when they cover large areas, odds are good you’re looking at a harmless condition that a 1920s researcher named “carapace spots,” after their resemblance to a turtle shell.
Wind damage, typically early in the avocado’s life, can lead to these shell-like patches. When strong gusts knock twigs and leaves into delicate baby avocados, their thin skins break and then heal the wounds with scar tissue. That’s all well and good, but the scar tissue isn’t so great at keeping up with the growing avocado. Here’s how the California Avocado Commission puts it:
“When the fruit grow they don’t expand evenly over the fruit and the scars fracture along lines of force. This is what causes the netting effect. If the skin is damaged when the fruit are very small the size of the russet area can cover a large percentage of the fruit by the time they are harvested.”
As wind is the primary culprit for the initial baby avocado injury, experts advise growers to plant avocado trees in low-wind areas, to construct windbreaks if needed and to trim avocado trees because large trees with dense canopies risk “acting as a large sail catching the wind.”
Insect nibbles can also lead to corky avocado skin
Insects, specifically, thrips, can also leave brown corky patterns on an avocado’s surface. Thrips, at a fraction of a centimeter long with little hairs hanging off their wings, use their needle-like mouths to slurp up avocado juices. However, according to the Hass Avocado Board, the insects only eat the top layer of the skin. The avocado is able to repair the skin, but not return it to its former shiny avocado glory. In the extreme, a thrip-nibbled avocado’s skin can be entirely brown and dusty looking. Continuing on the reptile theme, scientists call this “alligator skin.” But, as the Hass Avocado Board notes in a document about common avocado defects, thrips usually don’t affect the avocado’s interior, so as long as the fruit develop into full-sized avocados, they’ll still taste good.
But back to carapace spotting. Here’s what plant pathologist William T. Horne wrote in the 1929 California Avocado Association Yearbook:
“At these early stages the fruits are very tender and if they come in contact with another object, such as the edge of a leaf or some equally smooth surface, the fruits may become bruised without being scratched or the surface visibly broken. Such injured fruits do not all drop off and I have now fruits up to three inches in length which received scars when they were very tiny. At first these injuries are perfectly smooth and light olive color, but they soon turn dark and in time become heavily cracked. I have given these large blemishes the name “carapace spot” on account of their resemblance to a turtle’s back.”
SOURCES:
- Mary Lu Arpaia. Cooperative Extension Specialist. University of California, Agriculture and Natural Resources. Email correspondence September 2024.
- Avocado Fruit Abnormalities and Defects Revisited. Reuben Hofshi, The Hofshi Foundation; Mary Lu Arpaia Dept. of Botany and Plant Sciences, University of California, Riverside. California Avocado Society 2002 Yearbook 86: 147-162. Accessed October 2024.
- Avocado Quality Manual: A Guide to Best Practices. Hass Avocado Board. Section 7: Common Fruit Defects.
- Protecting Avocado Trees from Wind Damage. California Avocado Commission. Apr 17, 2013. Accessed September 2024.
- Effects of Wind on California Avocado Trees. California Avocado Commission. Apr 17, 2013. Accessed September 2024.
- California Avocado Association 1929 Yearbook 14:129 Carapace Spots Wm. T. Horne University of California, Citrus Experiment Station. Accessed September 2024.
- Some troubles of avocado fruit. R. G. Platt Extension Subtropical Horticulturist, University of California, Riverside. California Avocado Society 1972-73 Yearbook 56: 35-37. Accessed September 2024.
- William Titus Horne, Plant Pathology: Berkeley and Riverside. Professor. 1876-1944. University of California: In Memoriam, 1943-1945. Accessed September 2024.