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
Optimizing Fungicide Application Methods for Management of Sclerotinia in Dry Edible Beans
M. Wunsch, B. Kraft, M. Schaefer,   J. Hafner and S. Kallis, K. Cooper, L. Besemann and H. Eslinger
Methods
General Agronomics: The study was on a Maddock sandy loam soil type.  The previous crop was spring wheat.  The tillage operation consisted of disking once in the fall and spring cultivations (May 2 and June 6.  Supplemental fertilization:  19.4 lbs N, 49.8 lbs P, 45 lbs K, and 10.4 lbs S per acre were applied on April 19.  
Maintenance herbicide applications:  This field trial was first planted on May 17.  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/ac on May 19; the herbicide caused significant damage to the dry beans, and emergence was very poor.  The trial was replanted on June 8, and the pre-emergence herbicide was not applied again.  Post-emergence, 12 fl oz/ac SelectMax (clethodim, 0.97 gal/acre; Valent USA, Walnut Creek, CA) + 1 pt/acre NIS were applied for grass control, and  broadleaf weeds were manually removed by hand weeding.
Experimental design:  A randomized complete block design with six replicates.  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 20 feet long.  Untreated buffer plots were established between treatment plots.  
Planting details: : 'Lariat', a pinto bean was seeded at 90,000 pure live seeds/acre.  The study was planted on June 8.  
Fungicide applications:  Proline 480SC 5.7 fl oz/acre was the product and rate used for all applications.
Application timing:
Application A:   July 22 at 10:30 am - 1:30 pm; 95% of plants with an open blossom, 65-90% canopy closure (average 79%), canopy 15.0-22.5 inches tall (average 19 inches); temperature = 87-89˚F, relative humidity = 63-73%, wind speed = 2-6 mph.
Application B:  August 2 at 10:45 am - 3:15 pm; 45% of plants with at least one pod at maximum length, 99.5% canopy closure, canopy 16.9 inches tall (average 19 inches); temperature = 82-87˚F, relative humidity = 36-55%, wind speed = 2-4 mph.      
The canopy was closed on August 2 (relative to July 22), caused by lodging.  Because the use of the drop nozzles in the closed canopy would have resulted in significant crop damage, all drop nozzle treatments (treatments 8 to 12) were sprayed with boom-mounted XR11004 nozzles and 0.25% v/v Silkin spreader-sticker adjuvant on Aug. 2.
Application methods:  Applications were made with nozzles mounted 20 inches apart on a tractor-mounted boom or with nozzles mounted to the side ports or side and lower rear ports of Undercover 360 drop nozzles (Yield 360; Morton, IL).  The drop nozzles were spaced 21 inches apart (the same as the dry bean row spacing), and the tractor was driven such that the drop nozzles passed half way between each row.  The spray mixture was pressured with CO2.  The boom was situated such that the boom-mounted nozzles were 20 inches above the top of the average canopy height (39 inches above the ground for the first application and 36.9 in. above the ground for the second application) and the drop nozzle-mounted nozzles were at the midpoint of the average canopy height (9.5 inches above the ground for the first application).  The canopy was closed when the second application was made on August 2; because the use of the drop nozzles in the closed canopy would have resulted in significant crop damage, all drop nozzle treatments (treatments 8 to 12) were sprayed with boom-mounted XR11004 nozzles and 0.25% v/v Silkin spreader-sticker adjuvant on August 2.
Assessment of spray deposition:  Spray deposition within the canopy was assessed with the second fungicide application on August 2.  Because drop nozzles were not utilized on August 2, spray deposition was only assessed in treatments 2 to 7.  Water-sensitive paper (5 cm x 7.5 cm) for monitoring spray distribution (Syngenta Corp.; Basel, Switzerland) was utilized to assess spray deposition within the dry bean canopy.  Paper tabs were taped to the back of the water-sensitive paper such that they extended slightly beyond the water-sensitive paper, and the water-sensitive paper was fastened onto brackets attached to aluminum rods (to assess leaf deposition) or onto paper tabs attached to wooden stakes (to assess stem deposition) with paper clips on the paper tab.  The brackets on the aluminum rods were situated such that the lower bracket (to assess deposition to leaves in the lower canopy) and the upper bracket (to assess deposition in the upper canopy) faced in opposite direction such that placement of a spray card mounted on the upper bracket did not interfere with spray deposition to a spray card mounted on the lower bracket.  After mounting the water-sensitive paper, the aluminum rods and wooden stakes were driven into the ground within the plot, with care taken to ensure that leaf placement around and above the rods/stakes was representative of a fully closed canopy.
Assessment of spray deposition to lower leaves:  Water-sensitive paper was upward-facing and placed 5.6 inches above the ground (one-third of the height up the canopy; canopy height was 16.9 inches).
Assessment of spray deposition to upper leaves:  Water-sensitive paper was upward-facing and placed 11.3 inches above the ground (two-thirds of the height up the canopy; canopy height was 16.9 inches).
Assessment of spray deposition to stems:  Water-sensitive paper was side-facing and placed 8.45 inches above the ground (one-half of the height up the canopy; canopy height was 16.9 inches).
Analysis of spray deposition:  Spray deposition to the water-sensitive paper was evaluated with the Java-based computer program DepositScan (Zhu et al. 2011; Computers and Electronics in Agriculture 76:38 43.).  This program evaluates the following parameters:
DV 1:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.1 compose 10% of the total liquid volume.
DV 5:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.5 compose 50% of the total liquid volume.
DV 9:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.9 compose 90% of the total liquid volume.
Coverage (%):  the percent of the spray card surface that received fungicide product.  An average 36.3 cm2 was evaluated in each card.
Deposits (number/cm2):  the number of spray droplets per square centimeter.
Deposition (µL/cm2):  the calculated spray deposition volume; assessed with the formula Dd = 1.06 As0.455.
Sclerotinia incidence:  Percent of plants exhibiting symptoms of Sclerotinia stem rot (white mold); assessed August 29 to September 2 at the R7 growth stage (striping).  In plots with relatively even disease pressure across the plot, 30 plants (15 sequential plants in each of the southern and middle rows) in each third of the plot were individually assessed for the percent of the plant exhibiting white mold; 90 plants were assessed per plot.  In plots with noticeably uneven disease pressure across the plot, all plants in the middle and eastern rows of the plot were individually assessed for the percent of the plant exhibiting white mold.  
Sclerotinia severity index:  Average Sclerotinia stem rot severity across all plants, including those that did not develop disease, was assessed on August 29 to September 2 at the R7 growth stage.  In plots with relatively even disease pressure across the plot, 30 plants (15 sequential plants in each of the southern and middle rows) in each third of the plot were individually assessed for the percent of the plant exhibiting white mold; 90 plants were assessed per plot.  In plots with noticeably uneven disease pressure across the plot, all plants in the middle and eastern rows of the plot were individually assessed for the percent of the plant exhibiting white mold.  
Harvest and seed yield & quality assessment:  The beans were harvested September 12.  To facilitate accurate yield assessment, plot lengths were measured at 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 13.5% moisture level.
Statistical analysis:  Data were evaluated with analysis of variance.  (1) The assumption of constant variance was assessed with Levene's test for homogeneity of variances and visually confirmed by plotting residuals against predicted values.  (2) The assumption of normality was assessed the Shapiro-Wilk test and visually confirmed with a normal probability plot.  (3) The assumption of additivity of main-factor effects across replicates (no replicate-by-treatment interaction) was evaluated with Tukey's test for nonadditivity.  The spray deposition data did not always meet model assumptions; the distributional problems were corrected by subjecting the data to a systematic natural-log transformation, and ANOVA was conducted on the transformed data.  Data that were subjected to a natural-log transformation are identified in the summary table with a cross sign (‡) at the top of the column of treatment averages.  The yield data met model assumptions and were analyzed.  Single-degree-of-freedom contrasts were performed for all pairwise comparisons of isolates; to control the Type I error rate at the level of the experiment, the Tukey multiple comparison procedure was employed.  Analyses were conducted with replicate and treatment as main factor effects, and they were implemented in PROC UNIVARIATE and PROC GLM of SAS (version 9.4; SAS Institute, Cary, NC).
Assessment of treatment differences:  Analyses were conducted with replicate and treatment as main factor effects.  Single-degree-of-freedom contrasts were performed for all pairwise comparisons of isolates; to control the Type I error rate at the level of the experiment, the Tukey multiple comparison procedure was employed.  Analyses were implemented in PROC UNIVARIATE and PROC GLM of SAS (version 9.4; SAS Institute, Cary, NC).
Comments:  Early bloom and early to mid-pod fill, the growth stages at which dry beans are most susceptible to Sclerotinia stem rot, coincided with high temperatures and poor canopy closure.  Disease onset occurred late in crop development, reducing the impact of disease on yield.
Funded by the North Dakota Crop Protection Product Harmonization Board and Registration Board.
Oakes Irrigation Research Site
Variety trials Crop index Home page Report 2016
DISEASE CONTROL AND YIELD RESPONSE                                        
  n Drop nozzles were utilized only in the the first application on July 19, when 95% of plants had an open blossom.  The canopy was closed on Aug. 2; because the use of the drop nozzles in the closed canopy would have resulted in significant crop damage, all drop nozzle treatments (treatments 8 to 12) were sprayed with boom-mounted XR11004 nozzles and 0.25% v/v Silkin spreader-sticker adjuvant on Aug. 2.  
  n White mold developed late in crop development, resulting in very little impact on yield.  The canopy did not close until the R3 growth stage, and during the period in which dry beans are most susceptible to white mold - early bloom and early to mid pod-fill - daytime highs were often in the upper 80-degree to mid 90-degree Fahrenheit range, which is not conducive to disease development.  
  n High variability in disease pressure across the footprint of the trial (note the high coefficients of variation) and late disease onset made it difficult to differentiate the impact of nozzle type, nozzle placement, application pressure, spray volume, and adjuvants on disease control and pinto bean yield and quality.
  Fungicide applied:  Proline 480SC 5.7 fl oz/ac                                        
                            Sclerotinia stem rot Yield Test Weight
  Application Nozzle         Droplet Applic. Spray Adjuvant     Driving Incidence (%) Severity (%) Sev. Index (%) 13.5% moisture 13.5% moisture
  Timing Placement Nozzle     Size Pressure Volume       Sped    -------   Aug. 29 - Sept. 2  |  R7 growth stage   ------- lbs/ac lbs/bu
1 Non-treated control                         0 b* 0 a* 0 b* 0 a* 0.0 a*
2 A, B (Jul. 19, Aug. 2) Boom XR11004     M 40 psi 20 gal/ac None     5.9 mph 0 ab 0 a 0 ab 0 a 0.0 a
3 A, B (Jul. 19, Aug. 2) Boom XR11004     M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph 0 a 0 a 0 a 0 a 0.0 a
4 A, B (Jul. 19, Aug. 2) Boom XR11004     M 40 psi 20 gal/ac 6.4 fl oz/ac Masterlock 5.9 mph 0 ab 0 a 0 ab 0 a 0.0 a
5 A, B (Jul. 19, Aug. 2) Boom TT11001     M 40 psi 20 gal/ac 0.25% v/v Silkin   1.5 mph 0 a 0 a 0 a 0 a 0.0 a
6 A, B (Jul. 19, Aug. 2) Boom TT11001     M 40 psi 10 gal/ac 0.25% v/v Silkin   3.0 mph 0 ab 0 a 0 ab 0 a 0.0 a
7 A, B (Jul. 19, Aug. 2) Boom TT11002     M 60 psi 20 gal/ac 0.25% v/v Silkin   3.6 mph 0 ab 0 a 0 ab 0 a 0.0 a
8 A (Jul. 19) Drop Nozzle TT11001 (side ports), TX-VK6 (lower rear) M, F 40 psi 20 gal/ac None     4.2 mph 0 ab 0 a 0 ab 0 a 0.0 a
B (Aug. 2) Boom XR11004     M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph
9 A (Jul. 19) Drop Nozzle TT11001 (side ports), TX-VK6 (lower rear) M, F 40 psi 20 gal/ac 0.25% v/v Silkin   4.2 mph 0 a 0 a 0 ab 0 a 0.0 a
B (Aug. 2) Boom XR11004     M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph
10 A (Jul. 19) Drop Nozzle TX-VK3 (side and lower rear ports) VF 40 psi 20 gal/ac 0.25% v/v Silkin   2.1 mph 0 ab 0 a 0 ab 0 a 0.0 a
B (Aug. 2) Boom XR11004     M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph
11 A (Jul. 19) Drop Nozzle TX-VK3 (side and lower rear ports) VF 40 psi 10 gal/ac 0.25% v/v Silkin   4.2 mph 0 a 0 a 0 a 0 a 0.0 a
B (Aug. 2) Boom XR11004     M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph
12 A (Jul. 19) Drop Nozzle TX-VK6 (side and lower rear ports) VF 60 psi 15 gal/ac 0.25% v/v Silkin   7.5 mph 0 a 0 a 0 ab 0 a 0.0 a
B (Aug. 2) Boom XR11004     M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph
                          F: 2.53 0.53 2.02 1.04 0.58
                          P>F: 0.0090 0.8892 0.0379 0.4224 0.8392
                          CV: 38.8 26.6 49.3 14.9 0.8
* Within-column means followed by the same letter are not significantly different (P < 0.05; Tukey multiple comparison procedure).                            
                                               
SPRAY DEPOSITION WITHIN THE CANOPY                                        
  n Spray deposition was assessed in the second fungicide application on August 2.                                  
  n The canopy was closed on Aug. 2; because the use of the drop nozzles in the closed canopy would have resulted in significant crop damage, all drop nozzle treatments (treatments 8 to 12) were sprayed with boom-mounted XR11004 nozzles and 0.25% v/v Silkin spreader-sticker adjuvant on Aug. 2.  Because nozzle type, nozzle placement, application pressure, spray volume and adjuvant were identical for treatments 3 and treatments 8 through 12 on August 12, spray deposition was only assessed for treatments 2 to 7.
CHARACTERIZING SPRAY DEPOSITION WITHIN THE CANOPY - DEFINITIONS OF KEY TERMS:   DV 1:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.1 compose 10% of the total liquid volume.    |    DV 5:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.5 compose 50% of the total liquid volume.    |    DV 9:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.9 compose 90% of the total liquid volume.    |    Coverage (%):  the percent of the spray card surface that received fungicide product.  An average 36.3 cm2 was evaluated in each card.    |    Deposits (number/cm2):  the number of spray droplets per square centimeter.    |    Deposition (µL/cm²):  the calculated spray deposition volume; assessed with the formula Dd = 1.06 As0.455
  Spray deposition - Lower leaves                                          
  Application Nozzle     Droplet Applic. Spray Adjuvant     Driving DV 1 DV 5 DV 9 Deposits Coverage Deposition
  Timing Placement Nozzle Size Pressure Volume       Sped   µm µm µm No./cm² % µL/cm²
2 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac None     5.9 mph 0 a* 0 ab* 0 ab* 0 a* 0.0 a*‡ 0.00 a*‡
3 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph 0 a 0 ab 0 ab 0 a 0.0 a 0.00 a
4 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac 6.4 fl oz/ac Masterlock   5.9 mph 0 a 0 b 0 b 0 a 0.0 a 0.00 a
7 A, B (Jul. 19, Aug. 2) Boom TT11002 M 60 psi 20 gal/ac 0.25% v/v Silkin   1.5 mph 0 a 0 ab 0 ab 0 a 0.0 a 0.00 a
5 A, B (Jul. 19, Aug. 2) Boom TT11001 M 40 psi 20 gal/ac 0.25% v/v Silkin   3.0 mph 0 a 0 ab 0 ab 0 a 0.0 a 0.00 a
6 A, B (Jul. 19, Aug. 2) Boom TT11001 M 40 psi 10 gal/ac 0.25% v/v Silkin   3.6 mph 0 a 0 a 0 a 0 a 0.0 a 0.00 a
                      F: 1.98 3.20 3.13 1.02 1.00 1.04
                      P>F: 0.1162 0.0228 0.0250 0.4261 0.4361 0.4187
                      CV: 21.9 25.5 24.6 55.7 42.5 23.1
* Within-column means followed by the same letter are not significantly different (P < 0.05; Tukey multiple comparison procedure).                            
‡ To meet model assumptions of normality and/or homoskedasticity, analysis of variance was conducted on data that were subjected to a systematic natural-log transformation [LN(x) for data sets in which all numbers > 1.0; otherwise, LN(x+1)].  For ease of interpretation, treatment averages in the summary table are calculated from the untransformed data. 
 
 
                                     
  Spray deposition - Mid-Stem                                          
  Application Nozzle     Droplet Applic. Spray Adjuvant     Driving DV 1 DV 5 DV 9 Deposits Coverage Deposition
  Timing Placement Nozzle Size Pressure Volume       Sped   µm µm µm No./cm² % µL/cm²
2 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac None     5.9 mph 0 a* 0 a* 0 a* 0.0 a*‡ 0.0 a* 0.00 a*‡
3 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph 0 a 0 a 0 a 0.0 a 0.0 a 0.00 a
4 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac 6.4 fl oz/ac Masterlock   5.9 mph 0 a 0 a 0 a 0.0 a 0.0 a 0.00 a
7 A, B (Jul. 19, Aug. 2) Boom TT11002 M 60 psi 20 gal/ac 0.25% v/v Silkin   1.5 mph 0 a 0 a 0 a 0.0 a 0.0 a 0.00 a
5 A, B (Jul. 19, Aug. 2) Boom TT11001 M 40 psi 20 gal/ac 0.25% v/v Silkin   3.0 mph 0 a 0 a 0 a 0.0 a 0.0 a 0.00 a
6 A, B (Jul. 19, Aug. 2) Boom TT11001 M 40 psi 10 gal/ac 0.25% v/v Silkin   3.6 mph 0 a 0 a 0 a 0.0 a 0.0 a 0.00 a
                      F: 0.25 0.42 0.76 1.33 0.96 1.74
                      P>F: 0.9342 0.8305 0.5900 0.2833 0.4580 0.1620
                      CV: 26.1 26.6 23.5 51.0 133.9 29.0
* Within-column means followed by the same letter are not significantly different (P < 0.05; Tukey multiple comparison procedure).                            
‡ To meet model assumptions of normality and/or homoskedasticity, analysis of variance was conducted on data that were subjected to a systematic natural-log transformation [LN(x) for data sets in which all numbers > 1.0; otherwise, LN(x+1)].  For ease of interpretation, treatment averages in the summary table are calculated from the untransformed data. 
 
 
                                     
  Spray deposition - Upper leaves                                          
  Application Nozzle     Droplet Applic. Spray Adjuvant     Driving DV 1 DV 5 DV 9 Deposits Coverage Deposition
  Timing Placement Nozzle Size Pressure Volume       Sped   µm µm µm No./cm² % µL/cm²
2 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac None     5.9 mph 0 a* 0 ab* 0 a* 0 a* 0 ab* 0.0 b*
3 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac 0.25% v/v Silkin   5.9 mph 0 a 0 abc 0 ab 0 a 0 ab 0.0 ab
4 A, B (Jul. 19, Aug. 2) Boom XR11004 M 40 psi 20 gal/ac 6.4 fl oz/ac Masterlock   5.9 mph 0 ab 0 bc 0 ab 0 a 0 ab 0.0 ab
7 A, B (Jul. 19, Aug. 2) Boom TT11002 M 60 psi 20 gal/ac 0.25% v/v Silkin   1.5 mph 0 b 0 c 0 c 0 a 0 a 0.0 a
5 A, B (Jul. 19, Aug. 2) Boom TT11001 M 40 psi 20 gal/ac 0.25% v/v Silkin   3.0 mph 0 a 0 a 0 bc 0 a 0 ab 0.0 ab
6 A, B (Jul. 19, Aug. 2) Boom TT11001 M 40 psi 10 gal/ac 0.25% v/v Silkin   3.6 mph 0 a 0 a 0 bc 0 a 0 b 0.0 b
                      F: 6.84 8.53 8.36 1.25 3.19 4.27
                      P>F: 0.0004 < 0.0001 < 0.0001 0.3179 0.0231 0.0061
                      CV: 13.0 19.5 18.7 47.6 54.3 59.8
* Within-column means followed by the same letter are not significantly different (P < 0.05; Tukey multiple comparison procedure).                            
DV 1:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.1 compose 10% of the total liquid volume
DV 5:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.5 compose 50% of the total liquid volume
DV 9:  the distribution of droplet diameters such that droplets with a diameter smaller than DV.9 compose 90% of the total liquid volume
Coverage (%):  the percent of the spray card surface that received fungicide product.  An average 36.3 cm2 was evaluated in each card.
Deposits (number/cm2):  the number of spray droplets per square centimeter.
Deposition (µL/cm²):  the calculated spray deposition volume; assessed with the formula Dd = 1.06 As0.455
Oakes Irrigation Research Site
Variety trials Crop index Home page Report 2016