{{Short description|Abnormality of fruit skin}} {{About|russeting in agriculture|russeting in metalworking|Bluing (steel)#Russeting}} thumb|300px|right|Four pears featuring various degrees of russeting '''Russeting''' or '''russetting''' is an abnormality of fruit skin which manifests in russet-colored (brownish) patches that are rougher than healthy skin. It is a common feature in apples and pears. Russeting is typically an undesirable trait, which reduces the storage life of fruits and makes their appearance unattractive to consumers,<ref name=Lashbrooke>{{cite journal|title=Genome investigation suggests ''MdSHN3'', an APETALA2-domain transcription factor gene, to be a positive regulator of apple fruit cuticle formation and an inhibitor of russet development |last1=Lashbrooke |first1=J. |last2=Aharoni |first2=A. |last3=Costa |first3=F. |journal=Journal of Experimental Botany |year=2015 |issue=21 |volume=66 |pages=6579–89 |doi=10.1093/jxb/erv366 |pmc=4623677 |pmid=26220084}}</ref> although some cultivars, so-called russet apples, are appreciated for the feature.
==Causes== In apples and pears, russet results from micro-cracking of the cuticle, the outer epidermal layer of the fruit. The cuticle is a natural waterproof barrier composed of a polymerized cutin matrix embedded with waxes, which protects the fruit from outside stresses, and helps maintain post-harvest preservation. When the cuticle cracks, a corky suberized layer is formed on the fruit skin.<ref name=Lashbrooke/><ref name=Opara>{{cite book|editor-last=Jules |editor-first=Janick|title=Horticultural Reviews |volume=55 |chapter=Fruit Skin Splitting and Cracking |last1=Opara |first1=Linus U. |last2=Studman |first2=Clifford J. |last3=Banks |first3=Nigel H. |chapter-url=https://books.google.com/books?id=jdVY1nF_BjkC&pg=PA225|year=2010|publisher=John Wiley & Sons|isbn=978-0-470-65061-5|pages=225–}}</ref>
Apples are particularly susceptible to russet. Many naturally occurring varieties exhibit the feature consistently, while other cultivars may develop russet due to environmental stresses. As a result, cuticular structure is impaired, leading to reduced strength of the peel, which impacts handling and post-harvest processing. Russeting and cuticular cracks may accelerate the development of flesh browning due to oxidation, as well as softening of internal tissue due to the loss of an external support.<ref name=Lashbrooke/>
== Gallery == <gallery> Image:Egremont Russet Apple.jpg|An Egremont Russet apple, almost completely covered in russeting File:Conference pear 2017 C1.jpg|Conference pear </gallery>
==See also== * Russet potato
==References== {{reflist}}
Category:Plant physiology
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