| Oakes Irrigation Research Site |
| Carrington Research Extension Center * North Dakota State
University |
| P.O. Box 531, Oakes, ND 58474-0531, Phone: (701) 742-2744, FAX:
(701) 742-2700, |
| E-mail: |
Kelly.c.Cooper@ndsu.edu |
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| Optimizing Fungicide
Application Timing for Sclerotinia Control in Soybeans |
| M. Wunsch, M. Schaefer,
B. Kraft, S. Kallis, K. Cooper, L. Besemann, H. Eslinger |
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| METHODS |
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| General Agronomics: The study was on a Maddock sandy loam soil type. The previous
crop was spring wheat and the tillage operation consisted of field
cultivation May 2. The maintenance
herbicide applications were:
PRE-EMERGENCE Spartan Elite (sulfentrazone, 0.7 lb ai/gal, and
s-metolachlor, 6.3 lb ai/gal; FMC Corp., Philadelphia, PA) was applied
at 22 fl oz/acre on May 19 and POST‑EMERGENCE: Roundup PowerMax (5.5 lbs/gal of the a.i.
glyphosate = 4.5 lbs/gal of the acid equivalent; Monsanto Corp., St. Louis,
MO) was applied June 13 at 32 fl oz/acre with 1 lb AMS/10 gal and 0.125% v/v
NIS. |
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| Experimental
design: A completely randomized block design with
six replicates, with fungicide timing evaluated within each row spacing as a
separate experiment. The seeded plot
size was 5 feet (center to center) by 25 feet long. The harvested plot size
was 5 feet (center to center) and approximately 22 feet long. Every treatment
plot was separated by a non-harvested buffer plot. |
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| Planting
details: Pioneer 'P07T50R' (0.7 maturity) was
seeded at 165,000 pure live seeds/acre. The study was planted on May 17,
2016. Seed treatments used were Apron
Maxx RTA (5.0 fl oz/100 lbs seed) + Imidacloprid 4ST (3 fl oz/100 lbs
seed). Imidacloprid 4ST (Willowood)
contains 4 lbs/gal thiamethoxam; Apron Maxx RTA (Syngenta) contains 0.096
lb/gal mefenoxam and 0.064 lb/gal fludioxonil. Rhizobium inoculant: BYSI-N granular inoculant for soybeans (100
million Bradyrhizobium japonicum per gram; Lallemand Specialties Canada,
Saskatoon, SK) was applied in-furrow with the seed at a rate of
10.3 lbs/acre. |
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| Fungicide
applications: |
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| Application
details: Fungicides were applied with a 60-inch hand boom
equipped with 4 equally spaced TeeJet 80015VS flat-fan nozzles at a spray
volume of 15 gal water/A operated at 40 psi. |
| Application A: 07/08/2016; 47% of plants at the R1 growth stage (at least one
open blossom); 90-100% canopy closure in the 14-inch rows and 50% canopy
closure in the 28-inch rows. Wind
speed - 3 MPH, Temperature 79°F, R Humidity 53%. |
| Application B: 07/15/2016; 100% of plants
at the R2 growth stage (an open blossom at one of the top two nodes; could
not spray earlier because the wind speed was too high.); 100% canopy closure
in the narrow (14-inch) rows and 75-90% canopy closure in the wide (28-inch
rows); Wind speed - 2 MPH,
Temperature 75°F, R Humidity 48%. |
| Application C: 07/18/2016; 100% of plants at the R2 growth stage; 100% canopy
closure in the narrow (14-inch) rows and 90-100% canopy closure in the wide
(28-inch) rows. Wind speed - 5 MPH, Temperature 76°F, R Humidity 69% R2-100%. |
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| Application D: 07/20/2016; 90-100% of
plants at the R3 growth stage (a pod at least 3/16" long at one of the
top two nodes); 100% canopy closure in the narrow (14-inch) rows and 95-100%
canopy closure in the wide (28-inch) rows.
Wind speed - 5 MPH, Temperature 80°F, R Humidity 87%. |
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| Notes
and disease establishment: The trial was
established on a site with a previous history of Sclerotinia epidemics. To
sustain the soil moisture necessary for apothecia development, the trial was
irrigated aggressively to create conditions favorable for apothecia
production and Sclerotinia infection.
Sclerotinia incidence and severity were assessed on September 14 at
the late R7 growth stage using the 0 to 3 scale developed by Craig Grau (Grau
and Radke 1984; Plant Disease 68: 56-58):
0 = no symptoms, 1 = lesions on lateral branches only, 2 = lesions on
main stem, no wilt, and normal pod development, 3 = lesions on main stem
resulting in wilting, poor pod fill, and plant death. All plants were assessed in the middle two
rows of four-row plots (14-inch row spacing) and in one of two rows of
two-row plots (28-inch row spacing). |
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| Harvest,
seed yield and quality assessment: The trial was
harvested on September 26. To facilitate accurate yield assessment, plot
lengths were measured shortly before harvest. Yields were calculated on the
basis of a 5-ft plot width and the measured plot length. Seed moisture was assessed after the grain
was cleaned. Seed yield and quality results were adjusted from the grain
actual moisture to a standard 13% moisture level. |
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| FUNDED BY THE NORTH
DAKOTA SOYBEAN COUNCIL |
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| Oakes Irrigation
Research Site |
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| Home
page |
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Report 2016 |
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