Turkey photo by Jerry Davis
Fungal diseases that must be overcome to have a traditional Thanksgiving dinner

Tom Volk, Dept. of Biology, 3024 Cowley Hall, University of Wisconsin-La Crosse, La Crosse, WI 54601 volk.thom@uwlax.edu.

This page and other pages are © Copyright 1996-2006 by Thomas J. Volk. This page was last updated November 6, 2006.

Return to Tom Volk's Fungi Home Page -- http://TomVolkFungi.net

Thanksgiving at Nancy Weber's houseMycology (the study of fungi) and Plant Pathology (the study of plant diseases) can have a positive effect on everyone's lives. For example, there are fungi that can infect just about every kind of crop plant or animal, even those needed for Thanksgiving dinners. It is one of the jobs of the mycologist or plant pathologist to control or diminish the effects of fungi on these crops. The following list of fungi affecting certain crops highlights some contributions of mycologists and plant pathologists: None of these crops could be grown profitably and be easily available for consumers for their Thanksgiving dinners without these scientists' studies of the fungi and the crop plants. Some of these fungi cause post-harvest diseases, and some infect the crops directly. Most of these diseases are not a huge problem any more under prevailing conditions, mostly due to studies of fungal life cycles and pathogenic properties by mycologists and plant pathologists--- but there are always other diseases waiting to take their place!

I realize that different people have their own Thanksgiving traditions, but I have tried to include as many as possible from a wide range of geographical areas. In the list below the italicized fungus name is on the left, and the disease that must be overcome for the Thanksgiving food to be available is on the right. There are many other diseases that affect these crops that are not included-- for example there are entire books of just cranberry diseases! If you have anything to add or have comments or questions, please write to me at: volk.thom@uwlax.edu

Fungal diseases that must be overcome to have a traditional Thanksgiving dinner
© Copyright 2003-2006 by Thomas J. Volk, TomVolkFungi.net

Aspergillus flavus, A. parasiticus

Aspergillus flavus conidiophore with conidia
Turkey-X Disease**

**Turkey-X Disease deserves a special mention. Aflatoxin was first discovered by observing a "plague" that occurred on many turkey farms, particularly in England in the early 1960's, where the turkeys died rapidly and in great numbers. Since the causal agent for the disease was not known, it was simply called "Turkey X disease." Mycologists later discovered that the turkeys had been fed peanut meal contaminated with Aspergillus flavus and related species. Although aflatoxin is widely known for its carcinogenic properties, under the conditions present at that time these fungi produced aflatoxin in such great quantities as to rapidly kill the turkeys. This is no longer a problem since the peanut meal, if used to feed the birds, is monitored very closely for the fungus. There is no chance of turkey containing aflatoxin today.

Phytophthora infestans, cause of the Irish potato famine

More than a million people died of starvation in Ireland in 1845-1846, and another million emigrated, mostly to the east coast of America.

Late blight of potato
mashed potatoes
Synchytrium endobioticum Black wart of potato

It's a Chytrid, a fungus with swimming spores. It mostly lives inside the host cells of the potato-hence the endobioticum.

Alternaria solani Early blight of potato and tomato

Affects the fruits, stems and leaves, causing a wilt. Not surprisingly it occurs earlier in the growing season than late blight.

Rhizopus nigricans, Rhizopus tritici Soft Rot of sweet potato

A post-harvest disease, usually exacerbated by poor storage conditions and poor curing (drying). Affected potatoes become soft and watery.

Monilinia oxycocci

The main fungus responsible for cranberry crop loss in Wisconsin. Early infection causes crop loss. Infected fruits fail to ripen

Cottonball disease/tip blight of cranberrycranberries
Bremia lactucae Downy mildew of lettuce

A relative of Phytophthora, it causes lesions with geometrical margins on the lettuce, making it unattractive for sale. Severely affected leaves rot or dry out.

Didymella bryoniae (sexual state) and Phoma cucurbitacearum (asexual state)
collapsed pumpkin
Black rot of pumpkin, a phase of the disease called gummy stem blight.

Infected fruit may have black spots in the field and collapse soon after harvest from internal rotting. Doesn't that sound yummy?

Claviceps purpureaClaviceps purpurea Ergot contamination of cream and milk (through ingestion by the cow)

The fungus contain the precursor to LSD and other secondary alkaloids, some of which cause gangrene.

Aspergillus flavus, Aspergillus parasiticus Aflatoxin contamination cream and milk

Aflatoxin has been shown to be carcinogenic at 1 ppb (that's one part per billion).

Ustilago zeae-maydis

Although considered a delicacy in Mexico, corn smut is responsible for billions of dollars in corn crop losses worldwide.

Corn smut delicious sweet corn
Colletotrichum lindemuthianum Bean anthracnose

You've seen this one-- Green beans get horrible rotting black spots on them.

Cryphonectria parasitica chestnut blight Chestnut blight

Chestnut blight, accidentally introduced into North America about 1904, has virtually wiped out the American chestnut in its native range in the eastern USA.

Puccinia graminis Black stem rust of wheat

The main detrimental effect of the rust on food production is in the reduction of the amount of rolls & stuffing that are available. The fungus attacks the wheat and drains vital sugars from the plant, reducing the yield.

Gibberella zeae/ Fusarium graminearum
Head blight of wheat

Besides drastically decreasing the yield of wheat, this fungus harms the crop in another way-- it produces two major mycotoxins, zearalenone and deoxynivalenol.

Erysiphe graminis Powdery mildew of cereal grasses

Powdery mildews can cause significant loss of yields in cereal grasses and other types of crops.

Penicillium digitatum and many other species

The fungus rots the fruit and in many cases secretes mycotoxins into the food.

Rot of apples and oranges Penicillium digitatum on apple
Hemileia vastatrix Coffee rust

The rust cases premature defoliation of the plant, resulting in reduced yield and even death of the plant. Occasionally the unripe green berries are even infected.

Thielaviopsis parodoxa Pineapple disease of sugar cane.

So called because the fungus attacks the growing parts of the sugar cane and rots them, causing the cane to smell like overripe pineapples.

Aphanomyces cochlioides Aphanomyces root rot of sugar beet.

Attacks the large beet growing underground, often wilting the plant and causing death, or at least very low sugar yields.

Trichoderma viride Trichoderma conidiophores Green mold disease of mushrooms.

Trichoderma is a mold that can infect the mycelium and fruiting bodies of other fungi!

Sclerotinia sclerotiorumVegetarian stuffed turkey constructed out of tofu and gluten.  What will they think of next? Sclerotinia stem rot of Soybean, affecting Tofurkey production.

This is a sliced tofurkey from Thanksgiving dinner 2000 in Oregon with Kelly Collins, Nancy Weber, Eric Hill and others.

Yum! I can't think of anyone who wouldn't like stuffed vegetarian tofu turkey!


I hope that one of the things you're thankful for now is the work of Mycologists and Plant Pathologists!

For further information on plant pathogens that affect many types of crop plants and forests and what plant pathologists are doing about them, you should visit the home page of the American Phytopathological Society-- apsnet.org

For further information on what mycologists do, I highly recommend visiting the home page of The Mycological Society of America-- MSAfungi.org

Many thanks to my Biology Dept. colleague Jerry Davis for the tom turkey picture at the top of the page. Jerry is a wonderful nature photographer and outdoors writer for our local paper, as well as being syndicated all over the midwest. Please contact him for information about his photographs.

Be sure to visit my companion page, Fungi that are necessary for a merry Christmas

Return to Tom Volk's Fungi Home Page -- http://TomVolkFungi.net