E. Indiana and Ohio Northern Corn Leaf Blight Creeping into Ohio
Last week we reported that Gray Leaf Spot was being found in many corn fields. This week there is Northern Corn Leaf Blight (NCLB) moving into some areas, especially those areas that had a rain early last week. In those areas it appears that the NCLB spores were carried on the front and rained on to the corn due to the fact it was showing in the upper part of the canopy. Northern Corn Leaf Blight (NCLB) lesions are larger than Gray Leaf Spot (GLS) and are shaped like cigars. It is very important to note if you have NCLB due to how fast it can develop. New lesions of NCLB can be formed every 7 days, whereas it normally takes 21 days to form a new GLS lesion. Therefore, NCLB can catch many growers off guard. One week their crop may look green and healthy and the next week it can look “torched.”
The following site has good information on fungicide efficacy for GLS and NCLB as well as some other foliar diseases: University of KY CDWG Corn Fungicide Efficacy Table.
Hybrids differ on their susceptibility to GLS and NCLB. The chart below rates Beck's hybrids for their disease tolerance (the higher the rating the greater the tolerance).
The next few days are forecast to be well below average for temperatures. Usually this time of year we are talking about heat and drought and its effect on pollination. This year we will have many fields pollinating during a cold snap (and plenty of moisture). What effects might the cold temperatures have on pollination?
--- Cold weather will slow corn growth which means we will have an extended pollination window for those fields pollinating now. This will help to increase yields.
--- For those fields that are not quite pollinating yet, there is the possibility we could get some silkballing. This is a condition where the silks get caught up in the husk and don’t push out causing a barren ear or reduced ear size. This will have a tendency to happen to products that have a stronger silk push and longer husk coverage. It does not generally happen over the entire field rather to individual plants within a field.
--- Some leaf diseases prefer colder weather including NCLB. With the recent rains we have had be on the lookout for this disease. NCLB can decrease our photosynthetic area quickly, possibly reducing yields or standability.