Stubby Root Nematode in Corn

June 11, 2021

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.

• The two close-up slides illustrate what is commonly called “stubby root”.  Normally this is caused by Stubby root nematode but I think that the other species listed above can also cause very similar symptoms.  So don’t assume that because you have that symptom you have stubby root nematode.  You may have another species, or most likely a combination of species.
• The last slide shows a close up of a root system from a bad spot in a corn field in Calhoun County.  Note the swollen end tips on roots.  This could be a light case of “stubby root” but more likely those are individual galls from root-knot nematodes.  This could become a real problem as the second generation infects the roots and destroys the ability of the plant to take up water and nutrients.  Remember each root-knot female (one per gall) can produce 200+ eggs.

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.