By Darren Hefty

Conditions were just right (or wrong, depending on how you look at it) for the development of Northern Corn Leaf Blight (NCLB) this year in the heart of the Corn Belt.  Whether you had NCLB or would just like to protect yourself from it, I’ll highlight some management practices to increase your odds of a successful crop this year.

First of all, NCLB is a very common disease in the Upper Midwest.  It survives in corn residue, and spores are spread by wind and water.   Conditions are most favorable for disease when the temperatures are in the 60 to 80 degree range and it is humid and wet.  It is theorized that it takes six hours or more of water on the leaf surface for infection to take place.  Infections will produce brown lesions that run parallel to the leaf veins.  If you had NCLB in your area in 2014, your best management practices are:

  1. Tillage – If you can do tillage, burying the residue is a good way to lessen the potential for NCLB happening again in 2015.  Erosion is the obvious downside risk, though.
  2. Crop Rotation – Rotating to a non-host crop like soybeans can break the disease cycle.
  3. Resistant/Tolerant Hybrids – Seed corn breeders have done a good job bringing hybrids with some level of resistance to NCLB.  If this disease has been a problem in your area in the past, it would be wise to add NCLB resistance to your list of needed characteristics in the hybrids you choose.
  4. Fungicide Application – Fortunately, NCLB is a fungal disease and can be prevented with a timely fungicide application.  Timely is the key word.  You must spray before you have the disease to achieve control.  You must have great coverage as well, since fungicides can only protect the leaf area they come in contact with.  The most important leaves to protect to preserve yield potential are the ear leaf and those above it.  The optimum spray timing is normally from full tassel to silking.  However, if weather conditions are conducive, you may need to treat earlier (V6-V7).

Other tips regarding foliar corn fungicides:

  • We normally do not recommend fungicides between V8 and VT (Tassel).  However, if you need to spray then, you should avoid the use of adjuvants in order to lessen the crop injury risk.
  • Products to use include: Stratego YLD (4-5 oz/acre), Headline AMP (10-14.4 oz/acre), Quilt Xcel (10.5-14 oz/acre), and Fortix (4-6 oz/acre).