Question: If plants are diseased can that effect our breathing because if we’re breathing in poisened plants and not healthy plants will we be breathing anything but oxygen

Dionne Turnbull answered on 5 Nov 2018:

Don’t worry, even if there is a whole field of diseased plants there are still enough healthy ones around to produce oxygen. And more than 50% of the worlds oxygen is actually produced by phytoplankton in the sea! They are like tiny single-celled plants, they photosynthesise like plants do.
The air we breathe is about 21% oxygen, 78% nitrogen and 1% other gases like carbon dioxide.

Plant diseases aren’t such a huge problem in the wild, because natural environments (like a woodland for example) are a mixture of lots of different types of plants, so a disease can usually only damage a few of them. The big problem is in farmers fields – where a huge field is full of exactly the same plant. If disease gets to one, it can often spread to the whole field.

Great question!