As we head into November, I’m thinking ahead to the bounty of food that will be served on Thanksgiving Day.  Of course, being a plant pathologist, it’s also fun for me to think about what might go wrong (from a plant disease perspective) to prevent some of my favorite dishes from making it to the table.

Turkey

Given that turkey is an animal, rather than a plant-based food, one would think nothing could go wrong.  Ah, but then we have to consider the stuffing.  Stuffing is made, in part, from cereal grains (e.g., wheat) and one disease that could cause issues is Fusarium head blight (aka scab).  The Fusarium head blight fungus infects wheat grain heads causing shrunken kernels and thus reduced yields.  More importantly, the fungus can produce toxins that adversely affect human health.  Because of the health risks, grain crops are carefully monitored for Fusarium head blight (and other) toxins and may be destroyed if toxin levels are too high.

Potatoes

I have never met a potato product that I didn’t like, but mashed potatoes are my favorite.  I think this is because at Thanksgiving, my family’s tradition is to serve them not with gravy, but with homemade egg noodles cooked in turkey/chicken broth.  Everyone thinks this tradition is weird at best, but once folks have experienced “noodle gravy” they become converts.  From a plant pathology standpoint, the most famous disease that might limit my access to potatoes is late blight, the disease that caused the Irish potato famine of the 1840’s and 1850’s.  This disease can (and often does) decimate potato and tomato crops.  In potatoes, the pathogen not only totally wipes out foliage, but can infect tubers.  Once in storage, the tubers degrade not only due to the late blight pathogen, but also due to other pathogens that invade through the late blight-compromised tissues.  Eventually, late blight-affected tubers can end up a mushy mess (and not in a good, mashed potato sense).

Carrots

I have a great recipe for cranberry/butter/brown sugar glazed carrots I like to serve at Thanksgiving (the recipe is at the bottom of this page).  But if I store carrots too long in my refrigerator, they can turn to a slimy mess and be totally unusable for this delicious recipe.  The disease that causes this degradation is bacterial soft rot.  This disease is also one that causes potato tuber rot in combination with late blight.  Bacterial soft is an awe-inspiring disease.  The pathogen produces an enzyme that degrades pectin, the substance that “glues” plant cells together.  The enzyme, for all practical purposes, liquefies carrot roots (and a lot of other vegetables as well), making the carrots (and other vegetables) suitable for the garbage disposal and not the dining room table.

Cranberries

What Thanksgiving dinner would be complete without a cranberry dish of some kind?  Cranberry relish, cranberry salad and cranberry bread are all delicious additions to a Thanksgiving meal.  But cranberries can have their disease problems as well.  Wisconsin is the largest cranberry producing state in the US, so I see a fair share of cranberry samples come into my clinic.  The most common problems I see are a variety of fungal fruit rots.  I was very lucky for many year to have Lindsay Wells (a graduate student in Patricia McManus’ fruit pathology lab here at the UW-Madison) work in my clinic and she is really the person who taught me about cranberry diseases, particularly fruit rots.  Although Lindsay has moved on to greener pastures, I still reap the benefits of her tenure here in my clinic every time I diagnose a cranberry disease.

Pumpkin pie

Pumpkin pie is another of my favorites and I can scarf an entire pie in one sitting.  So, any disease of pumpkins is on my hit list.  The most common disease I encounter on pumpkins is powdery mildew.  While powdery mildews tend to be cosmetic diseases on most hosts, on pumpkins, powdery mildew can be severe enough to cause leaf browning and death, particularly of leaves in the centers of plants.  This loss of leaves is not lethal, but leads to smaller fruit size (and thus smaller pies).  This is definitely not good for a pumpkinophile like me.

Now that I have depressed you all, go forth and plan your own tasty Thanksgiving Day meal and have a great holiday!  Or if you’d like to join in the “fun”, let me know your favorite Thanksgiving dish (bean casserole or scalloped corn anyone?) and I’ll find a plant disease to ruin it for you.  I love my job!!

To learn more about common diseases and disease management, explore the Plant Disease Diagnostics Clinic (PDDC) website (https://pddc.wisc.edu/) and in particular, check out the University of Wisconsin Garden Facts fact sheets that can be found there.  Also, follow the PDDC on Facebook and Twitter @UWPDDC to receive updates on emerging diseases and their management.

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Glazed Carrots with Cranberry Sauce

• 1 16 ounce bag of baby carrots
• 1/4 cup butter
• 1/4 cup canned cranberry sauce (or use the whole can)
• 2 teaspoons brown sugar
• 1/2 teaspoon salt

Cook carrots in boiling water until tender.

Combine other ingredients in saucepan and cook until ingredients melt together.

Drain water from carrots and place carrots in serving dish.

Cover carrots with sauce.

Variation: try adding a little orange juice to the glaze.