Apples make the list every year, and this year they are first. More than 40 different pesticides residues have been found on Apples this year, and it can also make its way into apple juice and applesauce, so it would be a smart thing to buy any apple product organically. You could peel your regular apples to avoid most of the chemical residue, but you would also be peeling away most of the apples nutritional value which is located in, and just under, the skin.
Next is Celery:
This one doesn't fit the three main categories of foods with the highest pesticide residue, which are Leafy Greens, Berries, and Tree Fruit, so its a good one to pay attention to so you can remember on its own (though to me celery sure seems like a Leafy Green?) There are more than 60 different pesticides used on Celery.
Strawberries also make the list every year:
Strawberries have nearly 60 different pesticides found on them, mostly due to farmers trying to avoid fungus growth on them. Fewer pesticides have been found in frozen strawberries, however.
Another one to make the list every year, Peaches:
Peaches have more than 60 pesticides found on them, though significantly fewer pesticides are found in canned peaches.
At the top of the Leafy Green category, Spinach has nearly 50 different pesticides used on it. There are nearly as many found in frozen spinach, but fewer found in canned spinach.
Nectarines imported tested higher for pesticide residue than domestically grown Nectarines, and overall there were 33 different pesticides found on Nectarines
Another fruit that always makes the list, Imported Grapes have can have more than 30 pesticides on them, and raisins nearly as much. Wine was not tested, but its something to wonder about..
Sweet Bell Peppers:
These peppers make the list often, and any variety of color can have residue from nearly 50 pesticides on them.
More than 35 pesticides can be on your potatoes. Sweet potatoes have less of a chance of having a lot of pesticide residue than other potato varieties, however.
Blueberries often make the dirty dozen list, with more than 50 pesticides have been found on them. Most berry alternatives also have a lot of pesticides, even if they have not made the list this year.
Lettuce has been found to have more than 50 pesticide residues on their Leafy Green leaves.
Kale is usually known as a hardier plant that is disease and fungus resistant, but has tested high for pesticide residue in the past couple of years anyway.
Collard Greens scored the same as Kale this year and so have been entered as 13th on the dirty dozen list, having more than 45 pesticides detected on them this year.
These are the items you may want to consider buying as organic instead of picking up the cheaper regular varieties. The Environmental Working group estimates that if you do this, you will reduce your total pesticide consumption by up to 80%, a very nice and more easily obtained goal to have, even if you can't afford to go all organic this year!