I’VE BEEN LOSING TWO OR THREE POTATO STEMS A DAY. Something has been chewing them off below the dirt line where I’ve mounded soil around the plants. All in all, I’ve lost about eight stems over three days. If this keeps up, I worry that I’ll have serious potato problems.
The good news is that the damage has been confined to one section of potatoes and the potatoes themselves don’t seem to have been damaged. The bad news is that damage has been inflicted on both plants in pots and in the ground, so that likely rules out voles. They are bad at climbing and won’t crawl into a pot to get at the plants.
Voles would have been my first guess at what was causing my potato problems. But it could also be mice, insects or some kind of disease. I’m not sure. Another point of evidence is that today I just found a beet plant that also had been chewed off just below dirt level. The small beet root had bite marks in it and had cleanly been separated from the rest of the root.
Glycoalkaloids are toxic
My understanding is that potato stems are toxic due to glycoalkaloids. If people or animals eat stems they probably will have a burning sensation in their mouth and become very sick. That’s why I’m surprised that something is causing this problem.
Glycoalkaloids give potatoes their flavor, but green potatoes have too much and will make people sick. You should NEVER eat a green potato or even cut off the green part and eat the rest. The green is just an indicator that the potato has too much glycoalkaloids in the entire potato.
Clearly some bugs are immune to glycoalkaloids because I see cucumber beetles and other unidentified bugs eating the potato plant leaves all the time.
Cooperative Extension Ask the Expert service
I’ve asked the University of Vermont Cooperative Extension service what could be causing my potato problems. I’ve also sent pictures. In my article Organic Gardeners: You Are Not Alone there’s a link for the Cooperative Extension Ask the Expert service where they answer questions about plant growing problems.
Extension Educator Alice Mullen responded to the request and said it is either voles or cutworms. I know I have both in the garden, but after considering the information provided by the Extension Service, my guess is cutworms. The photo of the severed potato stem in the cutworm link looks very much like my severed potato stems. Plus, some of the potato stems that were severed were in a pot, which seems to rule out voles.
On the other hand, the beet seems to have been eaten by a vole. The link to the vole information mentions beets as a primary target and the bite marks at different angles are characteristic of voles.
Unfortunately, my options for defense against cutworms are limited. At this stage, I can’t put any type of protective barrier around the stems. There are just too many stems. I have to hope that the stems get big enough before too many get hit. By mounding up the dirt to the point where the stems are small enough for cutworms to do their thing, I’ve created an environment where they can cause damage even to well-established potatoes.
Are you having the same potato problem as me? Better yet, have you had the same problem and resolved it. Let us know by commenting below.