The page you linked clearly says 上御道 is read as うえみどう (Ue-midō). The page also says 上御道 was a small area located somewhere in 駒場 (Komaba) district.
Currently Achi village doesn't have a district name related to 御道 or 上御道 (zip codes of Ochi). I checked Googleマップ and 地理院地図, but found nothing relevant.
田 means "rice field", and is either read as den (in on-yomi) or ta (in kun-yomi). So 上御道田 (probably Ue-midō den) means "the rice field in 上御道".
Historically, there was a 宿場【しゅくば】 (post station) of 三州街道 (Sanshū highway, current Route 153) in 駒場. So my speculation is that this 御道 (Midō, lit. "the (great) road") probably refers to Sanshū highway. 上 (Ue) is a kind of prefix which means "up", "high" etc. Is this 上御道田 located somewhere along 三州街道?
That's all what I could gather on the net, but the page you linked is a part of this site, which is full of information on the history of Achi. If you really want to be sure, probably the author of this site is the best person to ask.
EDIT: Looks like うえみどう (Uemidō) was a small area located around here, and it was also written in kanji as 上見堂 or 上御堂 (堂 = small shrine, or hokora). The name 上御堂 appears in the official history book of Achi Village, 阿智村誌. Anyway, ateji was very common in those days, so うえみどう might not necessarily refer to Sanshū highway.