Northern corn leaf blight (NCLB) is a fungal disease that often emerges where corn is grown year after year in the same field, especially where there is reduced tillage. NCLB favors high humidity conditions, but it has difficulties developing in extreme temperatures, such as very cold and hot temperatures.
Elliptical, “cigar” shaped symptoms first appear on lower leaves and move up the leaves as time passes. Severe yield loss is expected when outbreaks occur before the silking phase.
Selecting resistant hybrids
Sanitation: NLCB stays dorm in infected plant parts until weather conditions are favorable. NCLB infects newly planted corn through splashing water. Preparing the land with tillage practices and removing the previous season’s corn residue are essential for prevention.
The sooner the better: It’s easier and more cost effective to overcome NLCB and control it during the initial stage of infestation. Make it a routine to monitor the field regularly and search plants for the presence of the above symptoms on a weekly basis.
Proper soil drainage: The presence of standing water will promote the spread of NCLB. Make an effort and improve areas on the field where water tends to accumulate and form puddles. If possible, cover the ground with polyethylene sheets to reduce water evaporation from the soil.
The following fungicides are used in one or more parts of the world: zoxystrobin, pyraclostrobin, picoxystrobin, propiconazole, and tetraconazole.
Note: Yield losses will probably be significant if outbreaks occur 5-6 weeks post silking.
It is difficult to manage NLCB organically. Growers should be aware of the risks they take when deciding to grow organically and planting varieties that are non-resistant.