Text for UF/IFAS/Plant Pathology “Introduction_History” PowerPoint
Slide / Text: The text below is supplementary to what is presented on the slide itself1 / The American Phytopathological Society (APS) is a non-profit professional organization. Their mission is “Discover and disseminate new knowledge of plant systems worldwide to meet humanity’s need for safe and nutritious food, affordable fiber, sustainable forests, and verdant landscapes; and promote the development and adoption of economically and environmentally sustainable practices to ensure plant health.” Website:
One department within the University of Florida/IFAS is the Department of Plant Pathology. Members of this department are located in Gainesville (main campus) and at 9 centers across the entire state.We are known for our research on diseases of diverse crops including citrus; vegetables such as tomato, pepper and cucurbits; ornamentals including foliage plants and flowering and woody ornamentals; field crops including soybean, peanut and sugarcane; and tropical fruits.
Website:
2 / There are 6 objectives for this course.
3 / Phytopathology is a hard word to remember, so we use “plant pathology” to describe this scientific discipline.
4 / Most people know what it meant when you state someone is a “doctor”. One of the best ways to describe a plant pathologist is to state we are “plant doctors”. We strive to keep plants healthy, just like the medical doctor strives to keep humans healthy!
5 / This is a 4-minute video that we hope would encourage students to consider a career in plant pathology. It was produced by the American Phytopathological Society.
6 / Plant doctors like to have fun too! These short videos (30 seconds each) are a lighter view to illustrate the importance of our discipline. Think about it – what would the world do without certain plants? No grapes for grape jelly on your PB&J or for wine. No cotton for your blue jeans. No fresh vegetables and fruits. No trees in the landscape. We need plants, and someone has to keep the plants healthy!
7 / Portions of the rest of this PowerPoint follow the story line from a coloring book that APS developed entitled: Plant Pathology: Past to Present. It is now available in English, Chinese and Spanish – free to download. High school and middle school students use the storybook for mentoring grade school students. A few plant pathologists have been known to get out their crayons too!
8 / Plant diseases are not new. A disease of grain crops called “smut” was recorded thousands of years ago in ancient Babylon. Stinking smut or common bunt disease of wheat can still be found in wheat fields across the world. It is caused by a fungus, and it really does stink. Obviously, you do not want infested grain being used to make flour for bread or tortillas or any other wheat-based product.
Note the web link in this slide. One resource that APS has on their website is the “APS Education Center” - There are lessons about various diseases, articles on plant pathogen groups, lab exercises, an illustrated dictionary . . . and more.
9 / This is another disease documented very early in human history.
10 / Rust diseases are still problematic in this world. Wheat stem rust has been a devastating disease in parts of Africa. Just like human diseases, new plant pathogens emerge or move to new parts of the world, and old pathogens find new ways to attack the plant – there will always be a need for plant pathologists and other scientists who work with plants! We have to eat, feed our animals, clothe ourselves and build shelters for our families.
11 / Today, we are encouraged to eat whole grain breads. But, at one time, white bread was the bread of the rich and dark bread was the bread of the poor. If you had white bread on your table, it meant that you had the money to “refine” the wheat grain and didn’t need rye grain to make your bread.
12 / One disease of rye grain (and other grain crops and grasses) is called “ergot”. The pathogen infects the plant ovary and replaces the grain kernel with a pathogen structure called a sclerotium (sclerotia is plural). A sclerotium is called "ergot". “Ergot” is the French word for "spur." The French noted some resemblance between the sclerotia and the spurs on rooster legs, hence “ergot”. These ergots were ground up with the healthy rye grains to make bread, and that led to vary serious consequences, including death. But, we eat fungi all the time. What would it matter if we ate the sclerotia/ergots?
13 / Ergot contains the chemical ergotamine, which causes gangrene. Wheat is graded
as “ergoty” when it contains more than 0.05%(a very small amount!) by weight of the ergot/sclerotia. In February 2016, the Egyptian government rejected a cargo shipload of wheat because it contained “ergoty” grain. They were rejecting it not only because the grain could be harmful, but just as important, Egypt is considered free of this disease and did not want the fungus introduced into Egypt.
14 / But, as with most things, there is a “good” side to ergot. In other words, scientists did determine that the ergotamines could be useful. Most are now produced by fermentation using the fungus, but some are obtained from grain deliberately grown to be infected with the plant pathogen and produce sclerotia/ergots.
15 / The lowly potato and its importance in history: Did you know that potatoes are native to Peru, and not Idaho? The explorers introduced it to Europeans, and it quickly became a food staple, especially among the poor. But, as with most monocultures (large amount of land producing the same plant species), disaster eventually struck in the form of a plant disease called “late blight”.
16 / The website shown here tells the story of this disease and its effect on the world.
17 / As with most of our plant diseases, late blight, which also affects tomatoes, is still a serious disease world-wide. And, as we will learn later, the pathogen is no longer considered a fungus.
18 / Why do the British drink tea? Once again, a plant pathogen affects the social and economic norms of the world!
19 / It is not just plant diseases of food crops that have affected world history! One of the first “economic bubbles” was “Tulip Mania”. Yes, the lowly tulip that we see in the florist shops each spring (too hot to grow tulips in Florida) also has its place in history.
20 / The tulip streaking in the 1600s that was so highly sought after was due to a virus; actually, we now know it was two (2) viruses. As we will learn in another PowerPoint presentation, viruses are usually spread from plant to plant by insects. The viruses affecting tulips is spread by aphids. The viruses are still present in southern Europe. But, in the U.S., when you see a streaked tulip, you are seeing the result of crop breeding.
21 / Tree diseases are important also! Most of you have never seen a chestnut tree or American elm tree because of plant pathogens introduced into the U.S. The original Dutch elm disease pathogen was introduced into the U.S. in the 1920s by furniture makers who used imported European elm logs to make veneer for cabinets and tables. The beetle that spreads the fungal pathogen had been introduced earlier into the U.S. Unfortunately, American elm trees had been planted extensively as a landscape tree, especially along streets, in the U.S. – essentially a monoculture. The disease eliminated American elm trees from the east coast and eventually made it all the way to the west coast of the U.S. by the mid-1970s. The photo shown here is from the University of Washington campus in Seattle in 2010. Great efforts have been made using chemical and biological controls to try to save these trees on the west coast and elsewhere, but treatments are not always effective.
22 / In Florida, we are facing a similar situation today. Laurel wilt disease affects trees in the Lauraceae family, which includes the native redbay and sassafras. And, it also includes avocado. The Florida Department of Agricultural and Consumer Services (FDACS) established a consumer awareness campaign called “Save the Guac!” – if you want to eat guacamole, we need to save the avocado industry and the avocado tree in your backyard (if you live in central and south Florida).
The link to a 10-minute video about this problem is shown on the screen and below:
23 / Laurel wilt disease has turned into a very complicated story. But, we do know that introduction of an exotic beetle via infested crate packing materials started the deadly process. In most parts of Florida, it was not truly appreciated how many native redbay, sassafras and other trees in the Lauraceae family composed our native forests. This is the classic story of not appreciating something until it is gone!
24 / One way the beetle and perhaps the pathogen was moved throughout the state was via firewood. People would cut down the forest (and landscape) trees that died from Laurel Wilt and use it for firewood at campsites. Everyone plays a role in limiting the spread of plant pests!
25 / Citrus greening or Huanglongbing (try saying that 3 times really fast!!) is another disease that requires an insect to move the pathogen (a bacterium) from plant to plant.
26 / Both the pathogen and the insect vector were introduced into Florida. This disease has had a dramatic economic impact on the citrus industry in Florida!
27 / Laurel wilt and Citrus greening (Huanglongbing) are just two diseases that illustrate the importance of plant security at our borders and ports of entry. While you may want to share the exotic fruit or plant you observed outside of Florida and the U.S., it may be infected with a pathogen or carrying an insect pest – Don’t Pack a Pest! The APHIS beagle brigade is an important part of U.S. plant and food security . . . and they are so adorable!
28 / We have just touched on a few plant pathogens that have influenced history and/or influence us today. There are many more!
29 / As with ergotamine derived from the plant disease “ergot”, there are other plant pathogens that have purposefully or accidently been determined to be useful to humans. One of them is a phytoplasma (special type of bacterium) that we learned will result in a more beautiful poinsettia. It makes the plant branch more to obtain a more dense, compact plant.
30 / And depending on your heritage, you may already be familiar with huitlacoche or corn smut. This is a Mexican delicacy. One person’s plant disease is another person’s favorite food!
31 / How many of you have seen Ganoderma coffee or tea advertised? This woody, shelf-like mushroom is the basidiocarp (sexual spore producing structure) of the Ganoderma lucidum complex. Compounds that this fungal complex produces have been used in Asian folk medicine for 2000 years, and we now know much more scientifically about these compounds and why they are effective.
32 / Do you like sweet dessert wines, especially Sauternes? But, did you know they were the result of a plant pathogen? So, a fungus that can easily destroy the Florida strawberry crop is highly desired in certain grape-producing areas of the world!
33 / We also use plant pathogens to control weeds. This is just one example: a virus discovered by UF/IFAS plant pathologists is patented for use to control the invasive (introduced) tropical soda apple, which is a major weed problem in pastures in the southern half of Florida.
34 / Probably the most useful plant pathogen is Agrobacterium tumefaciens, a bacterium that causes crown gall of many stone fruit crops. However, once plant pathologists learned how it infected plants and exactly how it caused the galls (tumors), it quickly became the basis of early genetic engineering research. Think of this pathogen as the “original genetic engineer”! But, we will save the mysteries of this pathogen for later.
35 / This is a list of sources of information on plant diseases and the pathogens which cause them.
36 / This is the link to the short (30-second) fun videos about the loss of plants due to plant pathogens, and why the world will always need plant pathologists!
Text for Plant Pathology PowerPoint “Introduction_History”, Page 1