I’ve written before about the unwanted and invasive wild parsnip that is making its way into Iowa from Wisconsin, where it has reached epidemic proportions. Ten years ago, we had none here in eastern Iowa, but those days are now gone. Not only has the invasion hit Iowa, but it has hit hard. You can easily see big swaths of the weed in roadside ditches and open fields. Our farm is bounded by two roadways, and each of these has a heavy infestation.
One problem is that wild parsnip is quite palatable to sheep — particularly when the plant is young and tender. The sheep learn to eat it as small lambs in early spring, when the tender shoots pose no health risk. We have a few of these plants in our fields for specifically this reason: the sheep generally eat it off as it emerges in the spring, and those plants die, leaving our acreage surrounded by wild parsnip in the roadside ditches but relatively free of it in the pastures. As the summer progresses, however, the chemical composition of the weed begins to change. By mid-summer, contact with the chemicals in its sap cause a skin reaction (blistering and discoloration) when exposed to the sun.
Because of their positive experiences with the plant in the spring, our lambs have no idea of its summer impact. When grazing along any of our roadside boundaries, they often stick their heads through the fence and nibble at the now-mature leaves, releasing the toxins in the plant’s sap and unknowingly smearing it all over their faces.
Since sun exposure is nearly unavoidable in our pastures, their faces begin to blister and to bleed as the blisters break, leaving open sores that then attract flies. The whole thing is a mess, and it all begins with the wild parsnip and it’s Jekyll-and-Hyde change at mid-summer.
The blisters cause much more of an issue than simply the comfort of my sheep. When there are only a few blisters, the effects of wild parsnip look much like sore mouth, which is contagious and can prevent our sheep from getting the health certificate necessary for out-of-state deliveries. When there are many blisters, it is pretty obvious that it isn’t sore mouth (which we haven’t had here for nearly a decade, by the way), but the poor sheep is stressed enough from the pain of the blisters to prevent normal behaviors like eating and drinking. (The blisters act and feel like a severe sunburn.)
Even worse, the blisters can continue to appear for up to six weeks. There isn’t much to be done except to continue eliminating the noxious weed from our fields and roadways. Thankfully, it seems that once a sheep ends up with a bad case of blistering, it usually teaches them to leave the wild parsnip alone in the future. But looking at Quan (above) makes me cringe each time I see the many blisters on his face. Hopefully he, too, has learned his lesson and will avoid wild parsnip from now on!