2013 was the year of Northern Corn Leaf Blight. Although many producers were able to pull off above average yields in places, the disease was still present and affected hybrids differently based on individual hybrid tolerance, management practices and disease pressure.
Northern Corn Leaf Blight is caused by the fungi Exserohilum turcicum, which thrives in humid climates. These humid and overcast days mimicked much of what the 2013 season was like for many farmers. Northern Corn Leaf Blight can be identified though their pale gray lesions. These lesions are usually 1-6 inches long and have a cigar shape to them.
Northern Corn Leaf Blight (NCLB) infection occurs after 6-18 hours of water standing on the plants surface. Infection can happen through the fungi spores that can be from the previous years corn crop in corn on corn rotations or can be blown in from the wind. The life cycle of northern corn leaf blight is normally a short window but spores from the disease can reproduce within a week which can increase the rate of spread and spore load.
2013 was unusual due to the exposure period of NCLB. Normally we encounter a 15-20 day window. 2013 saw a 45 day window which allowed the disease to take over in certain areas. Southwestern Ontario traditionally sees higher GIB infection over NCLB. However 2013 had conditions that were more conducive to the disease. NCLB in some cases actually aids in plant maturity and grain dry down.
To manage NCLB several steps have to be followed to minimize damage from this disease. NCLB has several different races, so selecting a hybrid that has a good NCLB score is very important.
Pioneer plant breeders rate their hybrids on a scale of 1-9, most hybrids fall between the 4-6 ranges. Areas with known NCLB should select hybrids that have higher tolerance. Fungicides are another tool to help combat the issue of NCLB. Fungicide may not fully control NCLB like it does for many other leaf diseases, but is a tool to help you manage you crop. Decisions to use a fungicide should be based on disease risk factors such as hybrid susceptibility, tillage system, disease and yield potential. Proper tillage will help reduce previous corn residue and also help decrease the NCLB inoculum available to infect the next years crop.
We cannot control the conditions that nature throws at us but with proper management and good stewardship we can manage what the outcome will be.
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