Is there an easy tool that you can recommend for creating barcodes/QR codes associated with each individual plant we're testing to speed up data collection?
Hmmm... I know there's a ton of QR code generators online, but you want a solution for a list of objects.
In google docs, there's an add-on which outputs a paper with the QR codes and names all together, pretty awesome. I tested this and it works.
Also, open office Calc has a QR code generating extension which you could try for larger numbers or offline use.