Spoiler alert: yes, they do. People have been looking for ways to diagnose plant problems and treat them from times immemorial. Not only do plant diseases affect the appearance of houseplants, but they also destroy half of the food crops. Shocking, isn’t it? Just imagine the world without plant diseases! Maybe we could finally solve the global hunger problem. However, it would only be possible with adequate research carried out both by scientists and by plant enthusiasts. But before getting down to plant diagnosis, it is important to come to grips with some basic points.