Hiring: Agricultural Technician

An Agricultural Technician is sought to provide technical support for the State Extension Agronomist with applied research and extension programming. This program performs applied research at seven UMD Research and Education Centers located across the state related to the production of corn, soybean, wheat, barley, and other crops of interest to Maryland producers. The incumbent may assist with research performed at private farms within Maryland. The incumbent will also assist with Extension programming, including preparation for field days, twilight tours, or other educational events.

To view the complete listing and to apply, go to https://ejobs.umd.edu/postings/117883. Best consideration date is April 4, 2023 and all applications must be submitted through the website. For questions or inquiries, contact Nicole Fiorellino at nfiorell@umd.edu.

2023 Maryland Tar Spot of Corn Research

Andrew Kness, Senior Agriculture Agent | akness@umd.edu
University of Maryland Extension, Harford County

Summary

Tar spot is a new foliar fungal disease of corn first discovered in the United States in 2015 and confirmed in Maryland in 2022 and was estimated to be the most significant yield-limiting disease of corn in the US in 2021 and 2022. As a new disease for our state, this project collected preliminary data on the distribution of tar spot in our state and compared the efficacy of different fungicide application timings. Through field surveys we identified and confirmed tar spot in eight Maryland Counties at a frequency of approximately 47% and at a relatively low severity rate (not exceeding 30%). These observations suggest that the tar spot pathogen can overwinter in Maryland, as it has expanded its range from two counties in 2022 to at least eight in 2023. Field evaluations of two fungicide programs: one pass program at VT and a two-pass program at VT followed by R2, we observed a significant difference in tar spot severity and plant lodging compared to the control; however, there was no difference in yield. Additional research on fungicide timing and the spread of this disease should be conducted in the future to help develop improved management recommendations.

Survey of Tar Spot Distribution in Maryland

Several fields were scouted for tar spot starting during late vegetative growth stages and frequency and intensity of scouting was increased from tassel through harvest. Initial scouting was focused in fields in Harford County near fields where tar spot was confirmed in 2022. In addition, reports were solicited from other Extension Agents and crop consultants/scouts throughout the state. Suspected positive samples were confirmed by laboratory technique and all positive samples were uploaded to the tar spot tracker map on corn.ipmpipe.org.

The first reported and confirmed incidence of tar spot in Maryland for 2023 came from a corn field in Cecil County on August 22. The second came from Carroll County on August 31, followed by Harford County on September 3. We confirmed tar spot in the additional counties of Kent and Queen Anne’s on September 19; Baltimore County on September 22; Caroline County on September 25, and Dorchester County on October 6 (Figure 1).

Figure 1. Map showing confirmed distribution of tar spot for the 2023 growing season (yellow). Map from corn.ipmpipe.org.

Several fields were scouted in Northern Harford County throughout the year surrounding fields where tar spot was confirmed in 2022. By the end of the season, tar spot was found in over 50% of these fields (9/16) at levels ranging from 2% to 25% severity (Figure 2). It was observed that tar spot severity continued to increase after black layer for as long as there was green, living tissue remaining on the plants. This increase in severity after physiological maturity does not affect yield but does make for a notably increased level of severity present at harvest and thus the potential for an increase in overwintering spores that will provide inoculum for the following year.

Figure 2. Corn leaf with approximately 10% tar spot severity. Tar spot symptoms include raised, black specks on the leaves.

An additional survey of 12 fields on Maryland’s Eastern Shore from Cecil to Queen Anne’s County was conducted on September 19. During this time, two fields were confirmed with tar spot. Severity was very low (<2%) in the field in Queen Anne’s County, and high in the field in Kent County (30%).

Altogether, tar spot was confirmed in 16 out of 34 fields (47%) scouted/reported throughout the state (Figure 3), with samples coming from as far west as Washington County (no confirmed samples) east to Cecil County (two confirmed samples) and south on the Maryland Eastern Shore as far as Dorchester County (one sample confirmed).

Figure 3. Google Earth map of fields scouted (blue markers) and confirmed (red markers) presence of tar spot. Markers are approximate locations and not precise to protect the identity of the landowner and/or farmer.

Weather conditions were favorable for tar spot on the Eastern Shore and Northern Maryland; however, severe drought conditions from Frederick County west may have prevented its widespread establishment in Western Maryland.

Based on this survey, tar spot appears to be established in all the northern counties east of Frederick and south on the Eastern shore to at least Dorchester County, at a frequency of approximately 40-50%. Judging by the confirmed occurrences in other counties in different states, it is likely that tar spot is present in more Maryland Counties than determined by this survey.

On-Farm Fungicide Trials

Fungicides are an effective management tool for foliar diseases of corn, including tar spot. Research from the Midwest has shown a positive response to fungicide applications in fields where tar spot disease severity is high. However, there is debate as to if one fungicide application made around VT is sufficient to control tar spot, as yield losses have been reported as late as R4. In 2023 we established an on-farm trial to evaluate the response to a single fungicide application compared to a two-pass program for managing tar spot in corn.

Field plots were established at a farm in Harford County, MD in a field immediately adjacent to where tar spot was found in 2022. Corn (Revere Seed ‘1307 TCRIB’) was no-till planted into soybean residue with a John Deere 1775 NT ExactEmerge™, 30-inch, 16 row planter at the rate of 35,000 seeds/acre. Rows 1, 2, 15, and 16 on the planter were shut off to create alleys between adjacent plots and to eliminate treatment overlap, as well as to ensure harvest accuracy. This resulted in 12-row plots that were between 75 and 150 feet long. Plots were arranged in the field in a randomized block with three treatments and five replicates (Figure 4).

Figure 4. Tar spot fungicide timing research plot layout.

Fungicides (Table 1) were applied at the VT and R2 growth stages using a DJI T30 drone calibrated to deliver 2.8 gallons per acre spray volume to the entire length of the 12-row plots. VT applications were made on July 12 and R2 applications were made on August 5. Trivapro 2.1 SE was used for all applications. Trivapro was selected because previous research has demonstrated that multi-mode-of-action products have the best efficacy against tar spot.

Table 1. 2023 Fungicide Treatments.

Treatment Product Name

Active Ingredient(s)

Application Rate (& Timing)
Nontreated Control N/A N/A
1X Pass Trivapro 2.1 SE

Benzovindiflupyr + Azoxystrobin + Propiconazole

13.7 fl oz/A (VT)
2X Pass Trivapro 2.1 SE

Benzovindiflupyr + Azoxystrobin + Propiconazole

13.7 fl oz/A (VT) & 13.7 fl oz/A (R2)

Foliar diseases were rated prior to fungicide application and approximately every two to three weeks following until harvest. Disease severity from tar spot was visually rated as the percent leaf area infected in the canopy from 10 random plants from the center two rows of each plot.

Lodging scores were collected at harvest by conducting a “push test” on 10 plants from the center two rows of each plot. The push test consists of pushing a corn plant approximately 30 degrees from vertical; plants that break have compromised stalk strength and were considered lodged.

Yield data were collected by harvesting 12 rows of each plot using a John Deere S780 combine on October 13, 2023. Yield data was exported from the combine monitor and RTK was used to correlate yield with plot locations since we were not able to collect individual plot weights. All yields reported are adjusted to 15.5% moisture. All data were analyzed using ANOVA and significant differences between treatments were separated using Fisher’s Least Significant Difference (LSD; α=0.10).

On-Farm Trial Results

Tar spot was first observed in the plots on August 29 present at a very low level (less than 2% severity). Overall tar spot disease severity was low throughout the season in these plots. One possible explanation for this is the early planting date, which likely allowed the corn to complete its critical reproductive growth stages before weather conditions were favorable for tar spot development.

Early disease ratings revealed a significant difference in tar spot severity (p=0.0176) in treated plots vs nontreated plots (Table 2). However, late disease ratings collected at harvest show an overall increase in tar spot severity, but no difference between treated and nontreated plots. This is likely due to the fact that fungicides can only offer around 14-21 days of protection. In this trial, the second fungicide application did not provide improved tar spot control compared to the single pass treatment; however, the single fungicide application at VT delayed tar spot infection compared to the nontreated control.

Table 2. 2023 Tar Spot Disease Rating and Harvest Data.

Treatment Tar Spot Severity (%) Lodged Plants (%) Grain Yield (bu/acre) Grain Moisture (%)
9/11/23 10/12/23
Control 3.05 a* 3.75 10.0 a 192.56 19.06
1X Pass 1.18 b 2.88   5.0 a 199.05 19.41
2X Pass 0.85 b 4.00   0.0 b 201.56 20.31
p-value 0.0176 0.4133 0.0680 0.2123 0.4343

*Treatments connected by the same letter are not significantly different from each other (α=0.10).

The control plots averaged 192.56 bu/acre with a low of 169.7 and high of 214.6; the single pass (1X pass) program yielded an average of 199.05 bu/acre with a low of 177.5 and high of 228.6 bu/acre; and the two-pass (2X pass) fungicide treatment yielded an average of 201.56 bu/acre with a low and high of 194.4 and 222.7 bu/acre, respectively. However, there are no statistically significant differences in yield between treatments (p=0.2123). Likewise, there was also no significant difference in grain moisture. Tar spot disease severity was relatively low; likely too low to impact yield in this trial, leading to no yield response.

The 2X pass fungicide program did improve standability of the crop at harvest, with 0.0% lodging, significantly better than the 1X program (5.0%) and the control (10.0%).

This work was supported by funding through the Maryland Grain Producer’s Utilization Board and in-kind support from The Mill. Special thanks to Clear Meadow Farm for their use of land and equipment making this research possible.

2022 Maryland Weed Control Results

Kurt Vollmer, Weed Management Specialist | kvollmer@umd.edu
University of Maryland Extension

Figure 1. Preplant applications of Liberty (left) and Gramoxone (middle) compared to the untreated check (right) 10 days after application at Wye REC. Images: Kurt Vollmer, Univ. of Maryland.

Results from the 2022 Maryland Weed Control Trials are now available. These trials evaluate crop injury (PHYGEN) and herbicide efficacy (CONTRO) for certain weed species. This data can be used to compare herbicide options crops including corn, soybean, and wheat. Each metric is based on a visual assessment on a 0 to 100% scale with 0 being no control/injury and 100 being complete control/plant death. Products with a control rating less than 55% offer poor to no weed control. Growers should use caution when selecting an herbicide program based on one year of data as environmental conditions and weed populations can vary across locations. A copy of this report can be accessed at  https://extension.umd.edu/sites/extension.umd.edu/files/2023-07/2022%20Weed%20Control%20Results_FINAL.pdf or by using the QR code to the right, or by calling your local extension office for a copy. For more information on how to interpret this report, contact Dr. Kurt Vollmer (kvollmer@umd.edu).

Assessing Options for Italian Ryegrass Control Prior to Soybean Planting

Kurt Vollmer, Extension Weed Management Specialist | kvollmer@umd.edu and Alan Leslie, Agriculture Agent
University of Maryland Extension

Italian ryegrass is a winter annual weed that often needs to be managed prior to soybean planting. In Maryland, populations of Italian ryegrass have been confirmed to be resistant to group 1 (Axial, Select) and group 2 (Harmony, PowerFlex) herbicides, but recent populations have appeared to develop resistance to glyphosate (Figure 1). With limited herbicide options, preplant control of Italian ryegrass will be challenging for growers. In the fall of 2021 through spring of 2022, a study sponsored by the Maryland Soybean Board was conducted at a farm site in Talbot County, MD to evaluate different herbicides and application timings for controlling suspected herbicide-resistant Italian ryegrass. This study had two objectives: determine the optimum application timing and herbicides to control Italian ryegrass ahead of planting soybeans. Italian ryegrass seed will germinate in both the fall and the spring, therefore herbicide treatments were applied in the fall, spring, and in the fall followed by a second application in the spring. Herbicide selections consisted of glyphosate applied alone and glyphosate plus either clethodim (Select Max), flumioxazin (Valor), or saflufenacil (Sharpen). Valor and Sharpen can be applied preplant in both winter wheat and soybean to control many different weeds and Select Max is an herbicide that is used to control many annual and perennial grasses after they emerge.

Figure 1. Herbicide-susceptible and herbicide-resistant Italian ryegrass following a glyphosate application.

Our results showed application timing and herbicide selection had a significant effect on Italian ryegrass control, density, and height, but there appeared to be no additional benefit when these two factors were combined. In the spring of 2022, Italian ryegrass density and height were lower with sequential herbicide treatments compared to single applications in the spring or fall (Table 1). This was reflected in improved control with sequential compared to single applications. With multiple germination periods, it is likely that two applications will be needed to provide better control of both early and late emerging Italian ryegrass.

Table 1. Italian ryegrass response to three different herbicide application timings.a

Application timing Control   Density   Height
  %   Plants m-2   cm
Fall 44 b   12 a   20 a
Spring 48 b   16 a   25 a
Sequential 81 a   4 b   15 b

a Means with the same letter do not differ significantly according to Fisher’s LSD (α = 0.05).

Italian ryegrass density and height were lower when Roundup was applied with Select Max compared to all other treatments, regardless of application timing (Table 2). This was reflected in a significant improvement in control with this treatment; however, no treatment provided over 95% control. These results indicate this Italian ryegrass population to be glyphosate-resistant (Figure 2). Tank mixing glyphosate and other herbicides did not always improve control. Sharpen is a broadleaf-selective herbicide that is commonly used to help control glyphosate-resistant weeds like marestail, but it will not control Italian ryegrass. Although, Valor can provide residual control of this weed, including it with Roundup did not significantly improve control over Roundup plus Sharpen or Roundup alone. The combination of Roundup plus Select Max appeared to have a synergistic affect; however, previous research at this site showed Select Max alone provided no more than 30% control. Additional research is currently being conducted to evaluate the level of resistance to these different herbicide groups. Moving forward, additional strategies, including non-chemical ones, will likely be needed to manage this weed before planting soybeans and other summer crops in Maryland.

Figure 2. Italian ryegrass response in June of 2022 following a previous glyphosate application.

Table 2. Italian ryegrass response in spring to selected herbicide treatments.a

Herbicide(s) Group Rate (fl oz a-1) Control   Density   Height
      %   plants m-2   cm
Roundup 9 36 38 b   16 a   25 a
Roundup + Select Max 9 + 1 36 + 16 87 a   2 b   13 b
Roundup + Sharpen 9 + 14 36 + 2 49 b   16 a   23 a
Roundup + Valor 9 +14 36 + 2 58 b   12 a   23 a

a Means with the same letter do not differ significantly according to Fisher’s LSD (α = 0.05).

 

On-Farm Research opportunity for farmers

The module “Farmer Adoption of In-Season Nitrogen Decision Support Tools” is approved for 0.25 Nutrient Management CEUs in Maryland and Delaware, and is available until February 15. It provides education, but is also letting farmers know about an opportunity to participate in UMD/UD on-farm research.

Please visit the link if interested: https://sites.udel.edu/canr-nmeq/continuing-education/farmer-adoption-of-in-season-nitrogen-decision-support-tools-0-25-ceu/

Soybean Checkoff Research Field Day

Local farmers and industry professionals are invited to join the Maryland Soybean Board on August 11 at the Wye Research and Education Center (124 Wye Narrows Dr, Queenstown, MD 21658) to learn about checkoff-funded research out in the field and enjoy a snakehead fish fry and barbeque dinner. Research to be featured includes a spray drone demonstration, use of forage soybeans to control deer damage, evaluation of growth-promoting projects, variety trials, cover crops, and weed management. CEUs are available. Although this is a free event, pre-registration is encouraged:

https://msbfieldday2021.eventbrite.com

Farmer cooperators needed for on-farm nitrogen trials

The University of Maryland and University of Delaware are looking for farmers throughout both states to participate in a research project evaluating decision making surrounding adoption of nitrogen  management tools (commercially available N models, drone imagery, PSNT). We will implement a field  trial in the 2021 growing season that contains six nitrogen rates applied to corn in four replicates in strips  (~15 ft wide by 300 ft long) requiring about 2.5 total acres. Participants will be trained on the use of various nitrogen management tools and will be paid for their participation in the trial (W9 submission to UMD required for payment) pending eligibility to receive EQIP funding. Participants must have the  ability to apply prescribed nitrogen rates and record yield at harvest using a calibrated yield monitor. We require participants to participate in a pre-season interview (in April 2021), a one-on-one post-harvest debrief session, and a focus group in November or December, all likely taking place virtually due to  COVID restrictions. Farmers who have not previously partnered with Extension on research projects are  encouraged to participate. If interested, please contact Dr. Nicole Fiorellino at University of Maryland at  nfiorell@umd.edu and Dr. Amy Shober at University of Delaware at ashober@udel.edu

The project title, “A solutions-based evaluation of barriers to farmer adoption of in-season nitrogen decision support tools”, is funded through Natural Resource Conservation Service Conservation Innovation Grant On-Farm Conservation Innovation Trials grant program awarded to University of  Maryland, University of Delaware, and Pennsylvania State University in 2020.

2020 Soybean Fungicide Trials

Alyssa Koehler, Extension Field Crops Pathologist
University of Delaware

Carvel Research and Education Center Georgetown, DE

2020 Soybean Foliar Fungicide Trial

 

Variety: CZ 3930GTLL treated with Poncho/VoTiVo + Ilevo | Planting Date: 5/11/20

Plant Population: 150,000 sd/a | Harvest Date: 10/22/20

Treatmentz % Green Stems at Harvesty Test Weight Moisture Yieldx Avg. Purple Seed Stainw Avg. Diaporthe/Phomopsis Seed Decayv
Control 6.2 a 55.0 a 15.8 a 67.2 ab 2.4 ab 1.2 a
Revytek (R3)

8 oz/a

8.3 a 55.4 a 15.6 a 69.7 ab 1.6 ab 0.4 a
Priaxor  (R3)

4 oz/a

4.9 a 55.5 a 15.6 a 65.4 b 0.8 ab 0.6 a
Veltyma (R3)

7 oz/a

10.0 a 55.2 a 15.6 a 75.7 ab 1.8 ab 1.0 a
USF0411 (R3)

8 oz/a

6.2 a 55.3 a 15.5 a 68.8 ab 1.6 ab 0.6 a
Delaro (R3)

8 oz/a

8.5 a 55.2 a 15.5 a 78.7 a 1.0 ab 0.8 a
Topguard EQ (R3)

5 oz/a

6.2 a 55.1 a 15.8 a 68.2 ab 1.8 ab 0.6 a
Lucento (R3)

5 oz/a

7.1 a 54.9 a 15.6 a 71.5 ab 1.8 ab 1.2 a
Miravis Neo (R3)

13.7 oz/a

4.4 a 55.5 a 15.2 a 71.2 ab 0.6 b 1.0 a
Miravis Top (R3)

13.7 oz/a

5.8 a 55.5 a 15.2 a 71.0 ab 1.0 ab 0.6 a
Quadris Top SBX (R3) 8 oz/a 8.7 a 55.5 a 15.3 a 74.9 ab 0.6 b 0.6 a
Miravis Neo (R5)

13.7 oz/a

6.9 a 55.1 a 15.4 a 71.9 ab 3.0 a 1.0 a
Miravis Top (R5)

13.7 oz/a

7.0 a 55.0 a 15.4 a 70.7 ab 0.8 ab 0.4 a
Miravis Neo (R3) fb Trivapro (R5)

13.7 + 13.7 oz/a

7.4 a 55.3 a 15.6 a 66.3 ab 0.8 ab 0.4 a
p-value 0.184 0.141 0.30 0.04 0.017 0.844
LSD (α=0.05) 3.654 0.452 0.491 7.52 1.35 1.05

zR3 treatments applied 7/30/20, R5 8/12/20 using a Co2 pressurized backpack sprayer equipped with extended range 8002VS flat fan nozzles calibrated to deliver 20 GPA at 40 psi. Plots were set up in a randomized complete block design with five replications. All treatments included 0.125% non-ionic surfactant, Induce.

y Percent of green stems out of total stems in rows 2 and 3 of each plot the day of harvest. Means followed by the same letter are not significantly different based on Fisher’s Least Significant Difference (LSD; α=0.05).

x Yield was calculated from the center two rows of each plot and adjusted to 13% moisture.

w Avg. number of seeds in 10g subsample from each plot with purple discoloration.

v Avg. number of seeds in 10g subsample from each plot with white/chalky appearance.

2020 Corn Fungicide Trials

Alyssa Koehler, Extension Field Crops Pathologist
University of Delaware

Carvel Research and Education Center Georgetown, DE

2020 Irrigated Corn Fungicide Trial – Rotated Field

 

Variety: Hubner H6187RCSS | Planting Date: 5/14/20 | Harvest Date: 9/15/20 | Planting Population: 32,000 sd/A   

 

Treatmentz

% GLS Incidence 14 daay % GLS Severity 14daax % GLS Severity 28 daa % GLS Severity 42 daa Canopeo green canopy cover

49 daa

Moisture Test Weight Yieldw
Veltyma (R1)

7 oz/a

24.0 ab 0.24 ab 0.48 ab 1.10 abc 47.2 ab 22.8 a 52.5 abc 227.2 a
Headline AMP (R1)

10 oz/a

22.0 ab 0.22 ab 0.52 bc 1.48 d 43.4 bc 22.8 a 52.7 bc 232.3 a
Priaxor  (R1)

4 oz/a

24.0 ab 0.24 ab 0.50 ab 1.36 bcd 43.7 abc 22.9 a 52.6 bc 227.8 a
USF0411 (R1)

8 oz/a

30.0 b 0.30 b 0.54 b 0.88 a 49.8 a 23.3 a 52.5 abc 228.6 a
Topguard EQ(R1)

5 oz/a

22.0 ab 0.24 ab 0.52 ab 1.30 bcd 46.0 ab 23.0 a 52.6 bc 229.4 a
Lucento (R1)

5 oz/a

22.0 ab 0.22 ab 0.48 ab 1.04 ab 48.0 ab 23.0 a 52.3 ab 231.8 a
Trivapro (V8) fb Miravis Neo (R1)

13.7 +13.7  oz/a

16.0 a 0.18 ab 0.50 ab 1.36 bcd 48.3 ab 23.6 a 52.2 ab 230.1 a
Trivapro (R1)

13.7 oz/a

24.0 ab 0.24 ab 0.52 ab 1.34 bcd 43.7 abc 23.1 a 52.5 abc 230.0 a
Trivapro (V8) (3 reps) 13.7 oz/a 30.0 b 0.30 b 0.50 ab 1.23 a-d 38.8 c 22.8 a 52.8 c 220.2 a
Miravis Neo (V8)

13.7 oz/a

20.0 ab 0.20 ab 0.52 ab 1.42 cd 39.3 c 22.8 a 52.8 c 224.8 a
Miravis Neo (R1)

13.7 oz/a

14.0 a 0.14 a 0.46 a 1.30 bcd 46.2 ab 23.3 a 52. 1 a 228.4 a
Control 86.0 c 0.88 c 0.70 c 2.50 e 39.5 c 22.7 a 52.9 c 218.1 a
p-value 0.0001 0.0001 0.0001 0.0001 0.007 0.108 0.05 0.315
LSD (α=0.05) 12.16 0.13 0.07 0.36 6.05 0.57 0.47 10.75

z V8 applied 6/24/20, R1 applied 7/14/20 using a Co2 pressurized backpack sprayer equipped with TP8002-VS flat fan nozzle nozzles calibrated to deliver 20 GPA at 40 psi with plots set up in RCBD with five replications. All treatments included 0.125% non-ionic surfactant, Induce.

 y Disease incidence was rated as percentage of 10 ear leaves with grey leaf spot lesions caused by Cercospora zeae-maydis. Means followed by the same letter are not significantly different based on Fisher’s Least Significant Difference (LSD; α=0.05).

x Grey leaf spot severity was visually assessed as the average % ear leaf covered in lesions per plot; means of 10 leaves per plot were used for analysis.

 w Yield was calculated from the center two rows of each plot and adjusted to 15.5% moisture.

 

Warrington Irrigation Farm: 2020

Irrigated Corn Fungicide Trial – Corn on Corn

 

Variety: Axis 64K24 | Planting Date: 5/11/20 | Harvest Date: 10/6/20 | Planting Population: 34,000 sd/A

Treatmentz Avg % GLS Incidence 14 daay Avg % GLS Severity 14daax Avg % GLS Severity

28 daa

Avg % GLS Severity

42 daa

Avg % Curvularia Severity

42 daaw

Canopeo green canopy cover

42 daa

% Lodging

72 daa

Test Weight Moisture Yieldv
Veltyma (R1)

7 oz/a

8.0 a 0.08 a 0.88 a 2.28 c 8.87 abcd 42.4 cd 6.0 ab 57.0 ab 20.26 abcd 218.8 a
Headline AMP (R1)

10 oz/a

18.0 abc 0.18 abc 1.00 a 2.02 abc 9.22 bcd 44.0 bcd 6.0 ab 57.0 ab 19.90 bcd 228.4 a
Priaxor  (R1)

4 oz/a

14.0 ab 0.14 ab 0.98 a 2.18 bc 9.14 bcd 40.9 d 8.0 ab 57.2 ab 19.80 de 220.9 a
Revytek (R1)

8 oz/a

16.0 abc 0.16 ab 0.84 a 1.56 abc 7.72 a 47.7 abcd 2.0 ab 56.2 c 20.38 ab 228.7 a
USF0411 (R1)

8 oz/a

16.0 abc 0.16 ab 0.86 a 1.20 a 7.60 a 51.8 a 0.0 a 56.7 bc 20.42 a 225.8 a
Delaro (R1)

8 oz/a

14.0 ab 0.14 ab 0.96 a 1.76 abc 9.50 bcd 41.4 d 2.0 ab 57.1 ab 19.86 cde 221.5 a
Topguard EQ (R1)

5 oz/a

12.0 ab 0.12 ab 1.02 a 1.82 abc 8.40 ab 46.8 abcd 10.0 b 57.0 ab 20.16 abcd 233.9 a
Lucento (R1)

5 oz/a

20.0 bc 0.20 bc 0.78 a 1.60 abc 7.76 a 49.2 ab 0.0 a 56.6 bc 20.26 abcd 227.0 a
Trivapro (R1)

13.7 oz/a

26.0 c 0.28 c 0.84 a 1.90 abc 9.08 bcd 46.3 abcd 2.0 ab 57.0 ab 20.12 abcd 226.7 a
Miravis Neo (R1)

13.7 oz/a

12.0 ab 0.12 ab 0.70 a 1.42 ab 8.58 abc 48.7 abc 4.0 ab 56.8 bc 20.32 abc 226.3 a
Quilt Xcel (R1)

10.5 oz/a

20.0 bc 0.20 bc 1.08 a 2.00 abc 9.74 cd 46.3 abcd 8.0 ab 56.8 bc 20.22 abcd 219.7 a
Control 98 d 1.18 d 2.7 b 11.18 d 9.90 d 32.5 e 26.0 c 57.5 a 19.38 e 205.2 a
p-value 0.0001 0.0001 0.0001 0.0001 0.004 0.0001 0.0003 0.05 0.005 0.33
LSD (α=0.05) 10.45 0.12 0.50 0.84 1.29 6.8 9.77 0.65 0.50 19.0

zAll treatments applied 7/14/20 using a Co2 pressurized backpack sprayer equipped with TP8002-VS flat fan nozzles calibrated to deliver 20 GPA at 40 psi with plots set up in RCBD with five replications. All treatments included 0.125% non-ionic surfactant, Induce.

y GLS incidence was rated as percentage of 10 ear leaves with grey leaf spot lesions caused by Cercospora zeae-maydis. Means followed by the same letter are not significantly different based on Fisher’s Least Significant Difference (LSD; α=0.05).

x GLS severity was visually assessed as the avg % ear leaf covered in GLS lesions per plot; means of 10 leaves per plot were used for analysis.

w Curvularia severity was visually assessed as avg % ear leaf covered in Curvularia lesions per plot; means of 10 leaves per plot were used for analysis.

v Yield was calculated from the center two rows of each plot and adjusted to 15.5% moisture.