Results From2011 On-Farm Fungicide Trials In Corn
DR. DAVID FOURQUREAN
LEXINGTON, KY.
Several years ago, fungicide use in corn
started to become somewhat common in
Kentucky and beyond. Ever since then,
university corn pathologists have worked hard
to conduct and evaluate research that allows us
to provide science-based recommendations to
producers.
Much of this research has been published in
refereed science journals – a mark of strict quality
control. Two key publications are listed at
the end of this article. Based on those papers as
well as on other research, the current consensus
of university pathologists is two-fold:
• Fungicides on corn can be beneficial when
pressure from certain foliar diseases (like gray
leaf spot) is significant.
• “Plant health” benefits in the absence of significant
disease can occur, but they are not consistent
or frequent enough to justify routine
fungicide use.
Although this consensus is well-supported by
years of research, scientists are always interested
in continuing to test and confirm, test and
confirm. In that spirit, we set up three on-farm
fungicide tests in Western Kentucky last summer.
These tests were all conducted according
to accepted scientific standards, including randomization
and replication. Plots were 120 feet
wide and ran the length of the field (two or three
reps in a RCBD). All three corn fields were conventional-
tilled and received no irrigation. They
were planted 9-17 May 2011. All received a single
application of Headline® at 6 oz/A by helicopter
at R1-R2. In Trial III, Strive 2 oz/A +
Mustang Max 3 oz/A + Protext Surfactant 0.48
oz/A were also included in the tank.
Results for each trial are shown in the tables
below. In order to interpret the tables, here are
some facts:
• “Stalk strength” was measured by pushing
50 stalks at chest height in each plot and
recording whether they sprung back or broke.
• “GLS” indicates the percent of ear leaf damage
from gray leaf spot at black layer. You can
see that all three trials had extremely low disease
pressure, because of dry weather preceding
and during grain fill.
• “Error (%)”shows the risk of being wrong if
you conclude that the Headline® treatment was
different from the untreated check. (This is the
P-value X 100.)
• “CV%” is a measure of the amount of variation
in the trial.
• There was a moderate drought during the
grain fill period.
Results
Trial I: Stalk strength appeared to be improved
in the Headline®-treated plots, although
with the error rate of 14%, so one should be
cautious about this observation. No significant
difference was seen for other variables.
Trial II: Stalk strength was significantly improved,
and yield was increased substantially
with Headline®, even though disease
pressure was almost non-existent.
Trial III: Yield was greatly improved with
Headline®, though no improvement in stalk
strength was noted. Moisture content was
higher in the Headline®-treated plots.
Conclusion
We observed substantial yield improvement
from Headline® in two of three on-farm trials, as
well as improved stalk strength in at least one
trial with 20-inch row spacing. The agronomic
benefits observed in these trials appear to be
“plant health” effects, because damage from foliar
disease was at trivial levels. It has been difficult
to see plant health benefits like these
consistently or predictably in university research,
and we don’t know whether we will see
them again. Nevertheless, these results justify
our continuing to conduct large-scale, on-farm,
scientifically valid tests this coming growing
season, in order to see whether we can reproduce
these kinds of agronomic improvements.
Key Literature
Paul et al. 2011. Meta-analysis of yield response
of hybrid field corn to foliar fungicides
in the U.S. Corn Belt. Phytopathology
101:1122-1132
Wise and Mueller, 2011. Are Fungicides No
Longer Just For Fungi? An Analysis of Foliar
Fungicide Use in Corn. APSnet Features.
doi:10.1094/APSnetFeature-2011-0531. Δ
DR. PAUL VINCELLI: Extension Plant Pathologist,
University of Kentucky
DAVID FOURQUREAN: Extension Agent for
Agriculture and Natural Resources – Trigg Co. Extension,
University of Kentucky
Figure 1. Trial I, white corn (Pioneer Brand
1431W) on 20-inch rows, previous
crop=wheat/doublecrop soybean.
Figure 2. Trial II, yellow corn (Pioneer Brand
1184HR) on 20-inch rows, previous crop=corn.
Figure 3. Trial III, yellow corn (Pioneer Brand
32B10) on 30-inch rows, previous crop=soybean.
Figure 1
Figure 2
Figure 3