I am sure that many of you are getting reports of “bad/sad” looking corn in a range of growth stages. As we all know this year’s corn crop has been through every possible type of stress. Don’t forget to look at the roots! Stubby root nematode is very common as are Columbia lance, lesion, Southern root-knot and to some extent sting nematodes.
I wanted to share these photos from a field in Newberry County from plants sent in by Jay Crouch. They show just how dramatic the effect of some nematodes can be. They also show that you don’t have to be in the Coastal plain to get nematode damage on row crops.
Stubby root is an interesting nematode with a very different life cycle from the “Big three” of root-knot, reniform and soybean cyst”. First it is a migratory ectoparasite. Second it becomes active at lower soil temperatures (i.e. first to feed in the spring on those tasty young roots). Third it does not care for hot soils, so it migrates vertically until it finds a cooler spot to stay in for midsummer.
In the Newberry county field we found only 20 to 40 stubby root nematodes in our soil samples. So it doesn’t take large numbers of stubby root nematodes to cause significant damage. My suggestion is if you have stunted corn in scattered areas across a field you check the roots for nematode symptoms.