December 2022: A Plant Pathologist’s Holiday Shopping List

Present Icon‘Tis the Season to buy holiday gifts.  I often have a difficult time coming up with ideas for what to buy for friends and family who seem to have everything.  Similarly, I’m a frustrating person to buy for; I just have too much stuff.  If you’re trying to come up with that perfect gift, and socks, a scarf or a necktie won’t do, consider a nifty plant disease-related gift that may put a smile on a loved one’s face.  I’m not talking about a greeting card or t-shirt with a plant disease design or pithy plant disease quote but actual diseased plant materials that you can gift to a friend.

Artisan wooden bowls

There are a couple of variations on this gift idea.  If you know of someone who really loves cherry wood (me, me!!), then consider finding a local woodworker who makes bowls from burls that form on the trunks of cherry trees.  These masses of wood (galls) are often the result of a fungal infection by Apiosporina morbosa, the black knot pathogen.  When infections occur on smaller branches, I refer to this disease affectionately as poop-on-a-stick, and the galls are not of much use.  However, larger black knot trunk galls are highly prized for their amazing grain patterns and can be used to make distinctive one-of-a-kind bowls.

The other types of bowls (or other wooden art objects) that are produced from diseased trees are those exhibiting spalting.  These wooden objects are produced from trees that are suffering from wood rot (typically white rot).  These rots are fungal in nature.  As the fungus colonizes the wood and begins to degrade it, dark lines can form at the interface between healthy and diseased wood.  If caught at the right time (before substantial degradation has occurred), the diseased wood can be shaped in to stunning artisan pieces with the decorative line patterns intact.

Walking sticks

Do you have a hiker friend who needs a gift?  If so, then consider a diamond willow walking stick.  Diamond willow is not a type of willow tree, but the result of certain species of willows being infected by canker-causing fungi (in particular the fungus Valsa).  Infection leads the formation of diamond-shaped sunken areas (cankers) on affected branches.  These sunken areas exhibit a distinctive light and dark (often reddish) contrast between healthy and diseased tissue.  The diamond shapes and color combination make the infected branches highly prized for making not only walking sticks but also furniture.


For a less expensive disease-related gift (the wood gifts described above can be quite pricey), consider giving a friend or loved one a poinsettia.  “What’s diseased about a poinsettia?” you may ask.  Well, the poinsettias that you buy at your local greenhouse or floral shop are infected with phytoplasmas.  Phytoplasmas are bacteria-like organisms that colonizes a plant’s food-conducting tissue.  Poinsettias, in their native habitat, are tall (we’re talking 10 ft. or more) and lanky.  The presence of phytoplasmas stunts infected poinsettia plants and makes these plants produce extra branches, thus yielding the beautiful, compact, bushy poinsettias that we have come to love.


For the gourmand on your shopping list, a can of huitlacoche (alternatively called cuitlacoche) might be the perfect stocking stuffer.  Huitlacoche is the polite name for common smut of corn.  This is a fungal disease where infection occurs through corn silks as the plants flower.  The fungus causes corn kernels to enlarge into huge, pasty gray masses (galls again).  Eventually, the interior gall tissue converts into powdery spores.  But, if you catch the galls when they are still solid and fleshy, you can use them for cooking.  Huitlacoche is a common ingredient in traditional Mexican cuisine, and many high-end restaurants now offer it on their menus.  While fresh huitlacoche is always a better choice, canned huitlacoche is readily available in specialty food stores, as well as online.


If you have questions about any of the disease gifts discussed above, or need additional ideas for plant pathology related gardening gifts, feel free to contact the PDDC by email at or by phone at (608) 262-2863.  Also, feel free to check out the PDDC website ( for additional details on plant diseases and their management, as well sample submission.  You can follow the PDDC on Twitter and Facebook (@UWPDDC) or email me to subscribe to the PDDC listserv, UWPDDCLearn, to receive updates on clinic services and educational materials.

Happy Holidays and good luck with your shopping!


Links in this article lead to sites that are for illustrative purposes only and are not an endorsement of any particular vendor or item for sale.

Update 12/9/22 

Here’s another plant disease gift idea I stumbled across (although there are some caveats with this one). . .

Oud perfumes and colognes 

Oud (also spelled oudh) refers to a dark, fragrant resin that is produced in the heartwood of agarwood trees (Aquilaria spp.) in response to infection by the fungus Phialophora parasitica.  Only a small percentage of agarwood trees (maybe 2%) become infected.  The combination of sap and fungus has a scent that evokes leather, saffron and smoke.  Unfortunately, oud has historically has been so valued (for a variety of purposes in addition to perfume production) that agarwood trees have been overharvested to the point where many species are endangered.  There is a move afoot to more sustainably produce oud by cultivating agarwood trees and artificially inoculating them.  So, if you decide that an oud perfume is your gift of choice, I suggest making sure the oud therein is from a sustainable source.

Update 12/14/22:  

And Santa’s plant pathology gift list grows longer (courtesy of Patty McManus, the former UW-Madison fruit pathologist) . . .

Noble rot wines 

Have a wine connoisseur who needs a holiday gift?  Then, consider noble rot wines.  These wines are produced from grapes that have been infected by Botrytis cinerea.  This fungus, if growing conditions are wet for extended periods of time, can devastate a grape crop, rotting the fruits on the vine.  However, if there is only a short wet period (which promotes infection), followed by drier conditions, the fungus causes a dehydration of the grapes without destructive decay.  This raisining of the grapes causes a concentration of sugars, and wines produced from noble rot grapes tend to be sweeter wines.  The presence of Botrytis cinerea also appears to add to the flavor profile of the wine, giving noble rot wines subtle hints of honey, beeswax and/or ginger.  Common noble rot wines include (but are not limited to) Tokaji (from Hungary/Slovania), Sauternes (from France) and Beerenauslese (from Germany/Austria).