We have a navel orange in our yard in Arizona. The fruit is beginning to ripen. We have picked a few so far. But in over half of the picked fruit, we have found black spots. Mostly near the bottom, navel, of the orange. We are novice to citrus trees care, as we bought this home 2 years ago. And the fruit up till this year was fantastic!! I need some help in caring for our navel orange, a "regular" orange, a grapefruit (pink) small lemon (pingball size fruit) a Ponderosa (huge lemon, size of a person's head). Any help would be grateful! Thank you, Tom Tamborski
Navel Orange Tree
Certified GKH Gardening Expert
Alternaria Fruit Rot effects both lemons and naval oranges, but can effect other citrus fruit.
It is caused by a fungus that attacks citrus fruit.
Alternaria Fruit Rot infects the interior of the fruit making it inedible.
It is best controlled by providing enough water and avoiding drought stress to the tree.
Applying the correct amounts of fertilizer will also help in reducing this fungus.
Removal of all infected citrus from your grove is very important in reducing the spread.
I'm listing several links for you with more information.