Several strobilurin fungicides are labeled for application on corn at around the V5 or V6 stage. A 2010 University of Illinois trial examining several application stages found the best response occurred when plant disease is present, says Carl Bradley, University of Illinois (U of I) Extension plant pathologist.

 In 2010, the U of I initiated trials examining several strobilurin fungicide times at two sites:

·      V5 (Fifth leaf, tassel initiation stage)

·      V15 (Kernel number determination stage)

·      VT (Tasselling)

·      R1 (Silking)

At the Urbana, Illinois site, low disease pressure below 2% occurred. No statistically significant difference in disease or yield occurred across all times and treatments.

At Monmouth, Illinois, though, high disease pressure –66% severity—resulted. Fungicide applications at VT or R1 boosted yields by around 20 bushels per acre. Meanwhile, earlier applications made at V5 or V15 had no statistically significant impact on yields or disease.