profile5

Disease Profile 5
Northern Corn Leaf Blight

http://plantpathology.tamu.edu/Texlab/Grains/Corn/Images/corn14.jpeg

Last updated by
Nick Dolezal
on March 5, 2002

Common Names of Northern Corn Leaf Blight:

-NCLB
-Leaf Blight

Causal Agent:

Species:
Setosphaeria turcica

Class:
Fungi

Host Range:

NCLB can survive on 22 plant species in the grass family. Here are some of the alternate crops, ornamentals, and weeds that Corn Smut can survive on:

Field Crops	Ornamentals	Weeds
Corn	none	Johnsongrass
Grain Sorghum		Sudangrass
Sweet Corn

Geographical Range:

NCLB can be found throughout the corn belt of the United States and other corn producing regions of the world. The pathogen is especially prevalent in the eastern part of the U.S.

Symptoms:

As seen on the photo at the top of this page, NCLB can significantly reduce corn yields by preventing photosynthesis in the plant along with robbing plat nutrients. The lesions that develop, initially on lower leaves and later on upper leaves, are generally found in a range from 1-6" long. The lesions can be light green, gray or tan in color. Severe infection can lead to complete necrosis of the plant leaf. Ear infection generally does not occur however, ear husks can be infected and exhibit symptoms.

Dissemination:

The plant pathogen is generally carried to new areas by wind currents. However, NCLB can also be introduced into a new field by the transport of infected plant material carried on farm equipment. Spores present along the soil surface may also be splashed onto a new plant by the impact of water droplets on the soil surface.

Disease Cycle:

Northern corn leaf blight over winters in plant residue as mycelium or conidia. In the spring, if the humidity is high and there is plenty of moisture available, the conidia germinate and infect a plant through open leaf stomates. The infection then grows to create a large lesion on the susceptible corn leaf and eventually grows to produce more spores for dissemination or for over wintering. The pathogen also may over winter as mycelium which is already present on a corn leaf.

Click here for an illustrated disease cycle of NCLB.

Control Measures:

One of the best methods of control for NCLB is to use resistant corn varieties. There is no complete resistance to the fungus however some varieties are more tolerant than others. Residue management is also a good alternative to controlling NCLB. As the fungus over winters as mycelium or in a spore, tillage will bury some of the primary inoculum present on the soil surface to prevent germination of the pathogen in the spring. Having a crop rotation that veers away from corn every couple of years will also limit the onset of NCLB by reducing inoculum buildup in the soil. Fungicides may also be an alternative for a farmer to use if he knows he has a problem with NCLB. The fungicide can be applied to reduce initial inoculum so as to prevent the onset of NCLB in large levels if growing conditions are prefect for the pathogen to grow and spread.

Recent Research-Summary: