Because Potatoes have their own category, and to add them to a sowingMachine or Planter you need to edit a completely different file within the actual map your playing. So making your seeder or plater have both the sowingMachine specialisation and planter specialisation will let you sow and plant everything except for potatoes. Generally most seeders or planters will only have the one category, however when Giants updated the Great Plains Planter an update or two ago, they allowed machines to have duel specialisation.
However if you stick with the FruitTypes approach you'll be limited on future maps with new crops to only being able to plant base game fruits. However I would recommend using the seedFruitTypeCategories code instead of the seedFruitTypes that way should you play on a map that has extra fruits added by the map author, you'll be able to plant those as well with the modded seeder. That will allow you to plant all the crop types shown above. Wheat barley potato sugarBeet maize canola oat sugarCane sunflower soybean oilseedRadish cotton grass If not and it has a line that maybe instead lists individual fruits like this: In the xml for the DB60 (though must admit the one I download weeks ago already has this in it.) check to make sure there is a line that reads:
