I would try with SEM. Of course you will need to coat the sample with gold/carbon. Even if later on you want to digg a little further and study the sample on TEM, the previously SEM analyses will help you a lot.

For example, if some element creates aggregates that are larger than 1 um, the information from TEM may be misleading, as you may end up either finding that specific element in less amount than expected, either finding a huge amount of the same, just because your sampling was done just over one of those aggregates.

Furthermore, as already answered by other colleagues, for TEM you will need specially thin areas, which may not be easy to obtain from your sample.

Good luck!

Definitely not a TEM as a first approach. SEM, if coumpound of interest contains something behind C, O, H, especially if it is non-organing compound. For organic compound Raman could be a better technique.

Many thanks to all my colleagues in this forum that have made recommendations as to which electron microscopy I should be using.  I have found the information you provided to be very useful and it is greatly appreciated.

God bless you all

It is not clear to me what may be the size of the particles with which you want to treat the leaves, before inoculating your sample with the fungus Alternaria solani.

I imagine that the size of the particles is very small, so in principle I recommend an ESEM of very high resolution. With ESEM you could observe your leaves, without any prior preparatory methodology.