Microorganisms live in symbiosis with plants. People don't realize how important they are. Fungicides and herbicides kill a lot of the microflora, disrupting this ecosystem. That's why I'm always telling people not to use fungicides unless they know which fungus they are treating, they know the fungus is causing the problem and they know the fungus is susceptible to the fungicide used. It's similar with antibiotic use in humans.
__________________ May the bridges I've burned light my way.