I am experimenting with using a $20 portable microscope for students to use in diagnosing plant diseases if/when my diagnostic course goes online this fall. My test sample was downy mildew on basil from my garden. 1/

The microscope is simple to use, but it takes practice and patience. I think using a separate macro lens would work better than the macro on the microscope. Enlarging symptom and sign images from my camera phone worked better than what I could image with the microscope. 2/

Pathogen structures using the microscope macro lens always seemed to be JUST out of view. Images also were not as clear as I would like. It’s fine if you know what you are looking at, but not if you do not. These are sporangia on the backside of the leaf. 3/

Microscopic images worked well. Structures are recognizable. When using my phone camera zoom function, structures can be easily seen. Sporangiophore and sporangia look good and are recognizable. Not bad for a handheld microscope. I used acid fuchsin stain and a tape mount. 4/

Here is the microscope: Carson Pocket Microscope 100-250x. The zoom on the microscope didn’t work as well as using the zoom function on my camera phone. It comes with a clip to attach it to your phone camera (works best without a case). 5/