Northern Corn Leaf Blight
Northern corn leaf blight, NCLB
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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 difficulture 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.
Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.