I confirm with what Vernon about there being no mosquito trucks or planes in Tuscany, they aren't used. Most agriculture uses natural chemicals and minerals, not what you'd normally consider pesticides. This is because there really aren't many large scale farms in Tuscany, most are pretty medium to small sized estates and are family-owned. Tuscans are also very aware of making conscious choices about avoiding OGM crops and using natural products on the land so that everything they grow can be considered natural if not certified 100% organic (although many are). People care about how food tastes and is grown, at least that has always been my impression and from the farms I have seen when visiting all parts of Tuscany.
Consider that the area between Cortona and Arezzo is highly agricultural, given that it is pretty flat. It is an area with canals made for agriculture. Aside from the towns that dot the landscape having been set up on the hills that exist (like Cortona), as soon as you leave the town the area is flat and thus cultivated. We biked the "Sentiero della Bonifica" from Cortona to Arezzo and passed by miles of orchards of apples and pears. The "bonifica" was when the swampy area created from overflowing rivers was controlled by man, creating canals and man-made lakes to contain runoff the last century to use the land for agriculture. A very similar story for Maremma.
So while most everyone uses natural chemicals when needed, if you want to stay away from agriculture in general, I'd suggest finding large estates that have lots of land around them. Many vineyards and olive groves dot the entire Chianti region and most don't use pesticides at all.