Southern root knot nematode (Meloidogyne incognita) can be yield limiting in areas of Southern Illinois.  This pest affects the root system of many hosts including soybeans.  The lifecycle of the southern root knot nematode can be 25 to 30 days depending on environmental and field conditions. This pest prefers high temperatures and sandy soils. Drought can also intensify the yellowing or stunting of plants.

Above ground symptoms can appear in patches of the field as early as the V1 to V3 growth stages.  To diagnose this nematode, it is very important that you use a shovel to inspect roots for below ground symptoms.  The diagnostic key is finding galls or “knots” on the root system because as nematodes feed, they will cause roots to swell.  Crop rotation with corn is not an option with southern root knot nematode because corn is a host.  Nematicides within seed treatments only offer protection for a few weeks and there is no other in season management option available.  There is resistance available within soybean varieties to manage southern root knot nematode; however, it is imperative that seed companies provide the proper soybean maturities with resistance for Illinois farmers.

Read more of Leo Rocha’s blog posts about soybean pathology by clicking here.