R' Eliezer ben Yaakov says: We may divert water from one tree to another provided that [by so doing] one does not water the entire field. Seeds that were not watered before the festival may not be watered during [Chol] HaMoed.  The Sages, however, permit [watering] in both these cases.

We may trap moles and mice in an orchard or in a grain field in the usual manner during [Chol] HaMoed and during Shemittah.  The Sages, however, say: In an orchard [we may trap] in the usual manner, but in a grain field [we may do so only] in an unusual manner.  We may block up a breach during [Chol] HaMoed, but during Shemittah we may build it up in the usual manner.