Tips for bacteria and virus observations?

iNat allows bacteria and virus obs, but there aren’t very many compared to plants, animals and fungi. Part of this is probably people assuming you need special equipment for it, but there are a couple obs of chicken pox on human skin, as that’s caused by a virus. Farmers are also skilled at identifying signs of bacteria and viruses on their crops. So it seems there are many opportunities to observe these things and we just don’t realize it. My question is- which ones are easy to find and what do they look like?


It depends – which part of the country do you live in? I only know about the Northeastern States.

In general, people mostly are not aware of plant pathogens, so they don’t keep their eyes open for any of the effects they can cause.



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“Blue isopod disease” (on iNat as invertebrate iridescent virus 31) is one easily visible virus which attacks a wide range of common garden isopods. It is not always easy to find isopods that have turned blue though, in many places only a small fraction of the population is infected.

Be careful not to mistake healthy isopods under bad lighting or blue non-isopod bugs for infected individuals though.


Cyanobacteria can sometimes be identified to species from ordinary photos, like Nostoc pruniforme. Lichens using cyanobacteria as their photobiont are easy to spot, and hornworts and liverworts can host cyanobacteria colonies (I think mostly Nostoc, but not certain) in their thallus appearing as dark spots. You can also tell if green stuff in the water is largely cyanobacteria vs algae with some practice. You can also tell if there is a lot of purple sulfur bacteria, or sulfur oxidizing bacteria in Thiotrichaceae. Red colored hypersaline lakes get their color largely from Halobacteria archaea, though red-colored green algae such as Dunaliella salina could also do that.


If you are familiar with a specific selection of garden plants (as individuals, not species), you will be able to spot when changes occur in them that aren’t part of the usual seasonal cycle. Then you can look up on gardening websites what their common names are, and the pathogen that causes them. I’ve tried this with roses in the past, and will be uploading a case of Late Blight from my tomatoes later, a fungus. Viruses were first identified in plants before people, so hopefully you can encounter an ill plant with definitive symptoms.


What viruses are easy to observe in the Northeastern States of the US? Some suggestions:

If you know how to recognize the Common Hackberry tree and you can find several of them, one or two of them will probably have the Hackberry Mosaic Virus on the leaves.

And also, if you look at enough American Pokeberry plants, some of them will have Pokeberry Mosaic virus showing on the leaves.

And if you look at maybe 100 or 200 rose plants, especially the wild introduced multiflora rose, one or two of them will probably have the Rose Rosette Virus disfiguring them.


Microscoped images/electron microscope images are rare to nonexistent here, but they would probably be a way to upload bacteria and virus observations

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That’s only true if we want to view the pathogens themselves directly.

But in many cases the symptoms are sufficient to ID the pathogen.


Of course. I’m not saying microscopes are the only way to do it. Just a method that hasn’t seen much use on here

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There are some projects for microscope obs. I haven’t contributed to them (yet), but I like to look.

The two I’m aware of:


Microscopic Microbes


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