So, you could obviously buy everything organic if you wanted to, but oranges will have minor benefits if any. The point of buying organic is apart from higher nutrients because of the way they are grown, herbicides and pesticides get ingested with non-organic. So best to avoid food that you eat regularly, and which you do not have to peel, i.e. is directly exposed to the chemicals.
The most important is oats, because non-organic oats have the most herbicides and pesticides, greater than used on other food. But bananas, oranges, mangoes, you will be fine. Avocado is a serious superfood, there is zero herbicide and pesticide penetrating through the skin. Apples, strawberries, etc better to go organic if having regularly, as well as veggies.
(All courtesy a podcast heard of a lead organic food researcher who has been doing this for years).