For smaller herbs and fruit, attention to detail is difficult because of the size of the plant. Examining seeds, leaves, and harvested plant matter is easy by using a microscope. However, no single microscope works for everyone. If you already have a smartphone, you might benefit from a universal phone microscope. Not only can you use this to see microscopic pests that may be hurting your plants but you can take photos to share with experts online.
However if you dont need to take photos or need something that doesnt need a cell phone the Agromax 60x-100x Pocket Microscope may be right for you.