Answer: I wonder if your tree has an insect infestation. Scale insects, aphids and mealybugs can all excrete a sticky substance called honeydew which can collect dirt and dust and make the fruit of your tree look dirty. Check the undersides of the leaves and where the leaves are attached to the stems of your tree for signs of insects. If you find them, and you control them, the sticky honeydew will be eliminated and so will the dirt on your fruit.
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