Hi, I am going for a field campaign to collect needles of Silver fir species, I would like to have a good DNA quality for NGS and I am looking for the best method to preserve the needles in the field. I have heard that freezing the needles right after collection would be ideal, however we won't have freezer with us for weeks. Silica gel is also not effective, and the DNA will be damaged after such a long time. Any advice? Many thanks