Here's a link to an interesting article from the Los Angeles Times about guerrilla grafters—gardeners who are trying to turn San Francisco's ornamental fruit trees on the street into fruit-bearing trees. The original idea was to ask the city to plant fruit-bearing trees, especially in low-income neighborhoods that could use the extra fresh produce. But San Francisco won't plant fruit trees on the street, noting the mess and rodent problems that can surface,
I can vouch for this—my landlord has planted a number of fruit trees in our backyard and while I appreciate the plums, loquats and oranges (the apples and grapes never make it to ripening due to squirrels, birds and probably rats), it is messy. We also had a rat living in our drain pipe this summer, gorging itself on loquats until I took away his drainage tunnel. Still: fresh fruit is quite a treat from the yard. And sharing fruit with the neighbors is the neighborly thing to do.
The grafters promised to only plant fruit trees where households agreed to look after them. Still the city said no. So now a secretive grafting campaign has begun. Grafters make a plan, target a tree and a household, then graft on a fruit-bearing branch and wait to see if it "takes." If so: fruit tree.
Pretty ingenious. Yes, it could get messy. Cars will be bonked by the occasional apple or pear, I suppose. But most likely fruit will be picked and enjoyed by people and vermin. I have lived and worked in a few San Francisco neighborhoods where grocery stores were either nonexistent or lacking in fresh produce. Fruit trees are a good idea as long as residents can look after them. I've never quite understood the mania for cleanliness in gardening, especially when living in a temperate climate that can bring about so much edible abundance.