Here is a distillation of ideas I've gathered from various plant forums–just something to kick off discussion.
Cold shouldn't hurt the micro organisms–cold slows most biological and chemical processes–rather it should preserve them. I suspect that they'll still do what they're supposed to do, only at a reduced rate.
Mycorrhizae thrive if well-fed, and some growers use molasses-based concoctions to accomplish that.
Chlorine and chloramine in public drinking water supplies will kill off a lot of them–probably something to consider before investing in expensive mycorrhizae inoculants.
Some people feel that commercial fertilizers reduce mycorrhizae populations as well.
Ken
