Sweet Orange Scab in Texas

Suspected SOS damageThe Plant Clinic is always abuzz with activity.  Recently (late July 2010) Sweet Orange Scab (a disease caused by the fungus Elsinoe australis) was confirmed by USDA-APHIS from a sample in the greater Houston area in Texas.  Since then, confirmed findings of the pathogen were recorded for various places in Texas and Louisiana.  Most recent was the detection of this pathogen in the valley – where the Texas citrus production industry is concentrated.  The first report of this disease was made in 1937 (Bittancourt & Jenkins) but it was not found in the US until July 2010. Since July, the large number of “finds” is a testament to the genetic detection tools that we currently have (PCR technology).  The widespread nature of the finds in this region do suggest that the problem may have been around much longer, and went undetected.  This disease primarily affects citrus fruit where you get the scabby symptoms on the rind of the citrus fruit.  Damage done on the fruit is superficial and DOES NOT affect the flavor or edibility of the fruit.  At the Clinic, we have the opportunity to work with this pathogen.  Our current effort (in collaboration with several researchers at College Station and at the Kingsville Citrus Center) is to isolate this pathogen. This is a slow growing fungus that can be a challenge to isolate.

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