How can you make good decisions about what to buy organic and what to buy traditionally grown? I like organic produce, but I also like affordable produce. Ideally, I like to buy locally grown foods. However, Chicago has a relatively short growing season, and organics don't tend to travel as well as their industrial mass-produced cousins. This translates to high prices on organic goods.
So how do I know what it makes sense to buy organic and what I can get away with buying the traditional versions of? One indicator might be the amount of pesticides used to grow the foods. This wallet card, which I found from a link on the Daily Bread, gives a nice guide to pesticide use on more popular vegetables and fruits.
Apples, Bell Peppers, Celery, Imported Grapes, Cherries, Nectarines, Peaches, Pears, Potatoes, Raspberries, Spinach, and Strawberries all get blasted with pesticides while being grown. You should buy organic versions of these products.
Asparagus, Avocados, Bananas, Broccoli, Cauliflower, Corn, Kiwi, Mangoes, Onions, Papaya, Pineapples, and Sweet Peas require relatively few pesticides even when grown in a non-organic manner. You can probably get away with standard versions of these veggies and fruit.
Wash everything well in any case, unless you want to evolve your pesticide resistence.