Dear Michelle,
     Thank you for reaching out to us in reference to Cara Cara Oranges and purchasing them.  The reason you are being told that they cannot be shipped and the reason you cannot drive hundreds of miles to purchase them is because of quarantines due to two diseases citrus canker and citrus greening. 
     Below you will find links to the Texas Agriculture Sites that explain both.
     The oranges can be bought locally to remain local.  You may want to check with your local nurseries there are several that sell citrus.

Citrus Canker (texasagriculture.gov)

Citrus Greening (texasagriculture.gov)

     If you have any additional questions please contact us at the information below.  Again thank you.

Regards,
Lynn Lucas
Volunteer

Fort Bend County Master Gardeners
Research and Gardening Help Desk Team
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https://fbmg.org/