![\"nlblifecycle\"](\"https:\/\/i0.wp.com\/www.uvm.edu\/extension\/cropsoil\/wp-content\/uploads\/nlblifecycle.jpg\")
<\/a><\/p>\nDisease Cycle<\/h3>\n
Northern corn leaf blight is caused by the fungus Exserohilum turcicu.\u00a0 It overwinters as mycelia and conidia in diseased corn stalks (Figure 1).\u00a0 In the spring and early summer, spores are produced on this crop residue when environmental conditions are favorable. Primary infections occur when spores are spread by rain splash and air currents to the leaves of new crop plants.\u00a0 Infection will occur if free water is present on the leaf surface for 6 to 18 hours and temperatures are 65 to 80\uf0b0F. Within 2 weeks of infection grey elliptical lesions begin to develop on the leaves.\u00a0 Over time the cigar shaped lesions become tan as they enlarge (Figure 2).\u00a0 Under moist conditions, the lesions produce dark gray spores on the lower leaf surface. As many lesions enlarge and coalesce, entire leaves or leaf areas may be covered. One of the most effective means of managing NLB is selecting resistant corn hybrids (Figure 3).\u00a0 Since we have not recognized this disease as a major threat focus on resistant hybrid selection has not been a priority. Hybrids with above average resistance to NLB should be planted.\u00a0 Work with your corn seed representative to select hybrids that meet these criteria. Dr. Heather Darby, Agronomic Specialist, UVM Extension Once again, I have seen increased Northern Corn Leaf Blight (NLB) pressure in our area.\u00a0 I have seen severe damage in the river valleys where dense fog and heavy dews are common.\u00a0 Northern leaf blight is a fungal disease found in humid climates wherever corn is grown. The … <\/p>\n
\nSecondary infections occur readily from plant to plant, and even from field to field.\u00a0 Infections generally begin on lower leaves first and then progress up the plant. Heavy dews, frequent light showers, high humidity, and moderate temperatures favor the spread of the disease.
\n<\/a><\/p>\nDisease Symptoms<\/h3>\n
\nIt is obvious that the more leaf area that becomes damaged from this disease the more yield and quality losses that maybe incurred. Generally, the damage on the plants is seen after silking, however, there have been earlier infections reported in the moist valley regions.<\/p>\n<\/a><\/p>\nDisease Management<\/h3>\n
\nSince corn residues harbor the disease, all fields that are grown for grain may be at the greatest risk for disease infection.\u00a0 In areas where NLB problems have occurred in recent years, reducing any previous corn residue is important to minimize disease inoculum and its effects. Corn residue can be reduced through several practices including crop rotation and moldboard plowing.\u00a0 Remember that this disease has been seen primarily in continuous corn silage fields in Vermont.\u00a0 Therefore, any amount of residue will increase the risk of this disease.
\nAlthough there are fungicides available to protect the corn from this disease they are generally not considered cost effective in corn silage systems. If you suspect that your corn has Northern Corn Leaf Blight please report the incidence to UVM Extension Agronomists Heather Darby.\u00a0 For more information please contact Heather Darby at (802) 524-6501 or email<\/a><\/span>.<\/p>\n","protected":false},"excerpt":{"rendered":"