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melanose

Q: The peeling of my grapefruit on my citrus tree is brown and it feels like sand paper. They are ripe and mature but what is wrong with them?

A: The disease is probably melanose, which is a common coastal fungal disease Melanosethat primarily occurs in grapefruit but can attack any citrus. The first symptoms on leaves are small, circular, dark depressions with a yellow margin, similar to canker.  Later, the spots become raised and turn dark brown.  The leaves may turn yellow and may drop prematurely, which can also be a symptom of other disease or insect problems.  Raised spots can are also be found on twigs, which may result in twig die back.  These spots can also occur on the fruit, which is why your fruit had the sand paper feeling on the rind.  The disease can be severe following rainy periods in the spring, particularly when such periods follow a freeze that has left an abundance of dead twigs.  This disease is also common on older, neglected trees.  Copper sprays are usually applied 2-3 weeks after petal fall and a second spray 2-3 weeks later. With a particularly wet spring, a second application may be needed. Citrus should be sprayed for melanose control in the spring following a freeze. Be sure to use a fungicide specifically formulated to be used on citrus. Follow the directions on the fungicide label; remember “the label is the law”. The best melanose management strategy is to remove small, dead twigs, and avoid overhead irrigation.  If you are concerned about citrus canker you can call the hotline:  800-904-3781.  Please do not bring in diseased citrus specimens into the county extension offices or local garden centers.