What Is Plant Pathology?

Feb 1, 2017 By Dr. Erika Rojas
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First, let’s start by defining plant pathology, or phytopathology.

I like the term phytopathology because it be traced back to Ancient Greek roots, where phyton= plant, pathos= suffering, and logia= study. If you put these words together you can guess that phytopathology is the study of plant ‘sufferings’, or diseases. So basically a phytopatholgist is a fancy word for a plant doctor!

Plant diseases influence what you and I eat every day. This may sounds like an exaggeration, but it’s true! Did you know that bananas, oranges, coffee, and cocoa are all currently being threatened by very scary plant diseases that affect where these crops are grown and how much they produce?  In fact, plant diseases have already played a major role in historical events. One of the primary culprits of the Irish Potato Famine in the 1800’s was a plant pathogen called Phytophthora infestans.

What Does A Plant Disease Look Like?

Plant pathologists figure out how to prevent plant diseases by understanding what they are, what causes them, and why they occur. Some of my favorite college experiences include field trips to farms and hearing farmers talk about their crops. I learned about plant diseases when they showed us areas with plants that ‘looked funny’ or abnormal, in comparison to all other plants. 

Many plant pathologists define plant diseases in similar way to how farmers describe them: a plant disease is as a condition where plant cells and tissues grow or function abnormally, and this condition often develops symptoms. Plant disease symptoms include leaf spots, yellowing or browning of tissues, wilting, or sometimes plants will not grows as quickly and produce as many leaves, flowers, or fruit, as other plants.

Living organisms that cause plant diseases are called pathogens, and there so many different types of pathogens that it is really hard to talk about all of them in a single article! The top plant pathogens include fungi, bacteria, viruses, and some very small worms called nematodes. Most times you will not be able to see plant pathogens on plants unless you have a magnifying glass or microscope, but there are some exceptions of course.

Plant diseases can also be caused by non-living organisms. Plant diseases caused by non-living things are called abiotic diseases (a= not or without, bios= living) and are commonly caused by weather, soil, or nutritional problems.

A Disease Detective!

You may be wondering how exactly plant pathologists study diseases and pathogens, especially if most plant pathogens are microscopic.

Well, many times we will bring sick plants back to our labs and observe them directly under the microscope. Other times we will try to make the pathogen grow in Petri plates that have a jelly-like substance called culture media, which is basically pathogen food. There are some pathogens that are too small to even see under a microscope or some are too fussy to grow on Petri plates, so to study these pathogens we may have to extract their DNA or keep plants diseased with the pathogen growing in a greenhouse.

For me, one of the coolest things of being a plant pathologist is that my job is never boring. Figuring out ways of stopping plant diseases requires understanding how pathogens, plants and the environment interact. To accomplish this, I get to spend a lot of time in the lab or outdoors and I often have to combine different disciplines, like microbiology, ecology, botany, and soil science and even engineering!

This means that I’m constantly working with very interesting people or learning new things. A huge plus is that all my work helps farmers protect the environment, grow healthier crops, and provide better food for all of us.