orange trees

Question

I have 5 different orange trees, and all have the same problem: small hard fruit, discolored, dark on sides. I also have a grapefruit tree without any problems. Can you suggest a solution?

Answer 1

You might be looking at Alternaria Rot. This is a fungal disease that attacks oranges but leaves grapefruits alone. It would cause those hard, dark sides on your fruits. This site offers some good advice on treating and preventing it:
http://ipm.ucanr.edu/PMG/r107100811.html