Foliar Wheat Disease Management with Xyway Fungicide – Oklahoma 2024

Meriem Aoun, Small Grains Pathologist

Department of Entomology & Plant Pathology Oklahoma State University

COOPERATORS: Dr. Meriem Aoun1, Brian Olson1, Tyler Pierson2, and Dr. Amanda de Silva Oliveira2

1Departments of Entomology & Plant Pathology, Oklahoma State University, Stillwater, OK; 2Plant & Soil Science, Oklahoma State University, Stillwater, OK.

PURPOSE:  To determine the efficacy of fungicides for controlling foliar diseases when applied to hard red winter wheat in Oklahoma.

LOCATION:  Entomology & Plant Pathology Research Farm; Stillwater, Oklahoma (Google Maps coordinates:  36.1266690, -97.1047885)

VARIETY: ‘OK Bullet’ hard red winter wheat                    

SOIL TYPE:  Norge loam

PLANTING DATE & RATE:  10-NOV-2023 at 90 lb/ac

FUNGICIDE APPLICATION DATES:

Dribble application over top of row and impregnated Fert GR: 10- NOV-2023

Flag leaf application @ Feekes’ growth stage 10.1 (GS 10.1: heads (awns) just starting to emerge from the boot): 19-APR-2024.

TARGET ORGANISMS (DISEASES): P. striiformis (stripe rust), Puccinia triticina (wheat leaf rust), Blumaria graminis f. sp. tritici (wheat powdery mildew), and Zymoseptoria tritici (Septoria leaf blotch)

PLOT DESIGN: Plots were 49 in. (7 rows; 7 in. spacing) by 20 ft, replicated four times in a randomized block design. Data were analyzed using R version 4.1.3.  Mean separation (LSD) test was conducted only if ‘F’ test was significant.

CULTURAL PRACTICES:

Fertilizer: Based on a soil test with a 50 bu/ac yield goal, 150 lbs/ac of 46-0-0 (Urea) and 150 lbs/ac 18-46-0 (Diammonium Phosphate/DAP) dry fertilizer were applied on September 9, 2023. On Feb 7, 2024, a top dress with 50 lbs/ac of 46-0-0 (Urea) was applied.

Herbicide:  None applied

Insecticide:  Gaucho 600 (2.4 fl oz/cwt) applied as a seed treatment to limit barley yellow dwarf

Irrigation:  No irrigation provided

METHOD OF APPLICATION:  Fungicides were applied with a CO2 wheelbarrow sprayer as a broadcast foliar application using flat fan nozzles (8003EVS) spaced 18 inches apart. The sprayer was calibrated to deliver fungicides at a rate of 15 GPA.

DISEASE ASSESSMENT: When sufficient foliar disease was present, plots were evaluated for type of disease and rated for percent infection using modified keys based on, “A Manual of Assessment Keys for Plant Disease. 1971. Clive James. Canada Department of Agriculture Publication No. 1458.” In this rating system, we took the percentage of leaf surface area covered by a disease.

HARVEST METHOD: Plots were harvested with a Wintersteiger Delta small plot combine. Grain weight, test weight, and moisture content were collected from each plot. Grain moisture at harvest was ~ 8% for all plots. The grain yield of the plots was adjusted to 12% moisture.

GENERAL OBSERVATIONS

Fall and winter rains (accumulated rainfall OCT-FEB was 10.9 inches) in Stillwater provided adequate moisture for good wheat growth and development. The accumulated rainfall in spring of 2023 (March – May) was 11.6 inches with the highest levels of moisture recorded in May 2024 (7.5 inch). By early April, the wheat was ahead of schedule, with the flag leaf appearing around two weeks earlier than normal. Low levels of barley yellow dwarf (BYD) infections were present but scattered randomly across the trial. Although BYD may have slightly impacted yield it was not a major concern. 

Stripe rust was the most prevalent disease in April and May and was early and severe. Stripe rust was first observed on March 31 in this trial. On April 19, stripe rust severity reached 49% on average on the untreated check. The stripe rust severity in the Xyway trial was rated on April 19, which was just before the flag leaf application of Adastrio (in treatments # 6 and 11). Leaf rust was also severe around the last week of April – early May. As leaf rust and stripe rust co-occurred in the Xyway trial at high levels, stay green ratings were collected on May 1 and May 9, 2024. Foliage senesced quickly after May 9 and no more ratings could be made. No indication of phytotoxicity by any fungicide treatment was observed. The rainfall in May delayed harvest by a couple of weeks. The plots were harvested on June 19, 2024.

SUMMARY

Results from this trial demonstrated the efficacy of some fungicide applications to manage foliar fungal diseases (stripe rust and leaf rust) (Table1). The average stripe rust severity on the untreated check reached 49% on April 19. The average stay green on the untreated check was 30% and 2.5% on May 1 and May 9, respectively. Stay green ratings accounted for both leaf rust and stripe rust infections. Yield (adjusted to 12% moisture) ranged from 22.9 bu/ac to 83.2 bu/ac. Test weight ranged from 49.0 to 59.9 lb/bu. For the untreated check, yield was 22.9 bu/ac and test weight was 50.2 lb/bu.

The most effective fungicide treatments in this trial were treatment #6 (Xyway LFR 8.9 + 10-34-0 @ 6 gallons/A dribble over top of row fb Adastrio 8 oz/ac + 0.25% v/v NIS @ flag leaf) and treatment #11 (Xyway LFR (8.9 fl oz) Impregnated Fert GR (11-52-0) 50 lbs/A in-furrow @ planting fb Adastrio 8 oz/ac + 0.25% v/v NIS @ flag leaf). There was a significant disease control and yield benefit by applying Adastrio 8 fl oz/ac at flag leaf stage. Treatments #9, 10, 4, and 5 (table 1) also performed better compared to the untreated check. Xyway LFR impregnated Fert GR or dripple application at a rate ≥ 8.9 fl oz significantly reduced rust diseases and consequently increased yield compared to the untreated check.

Table 1.  Summary of foliar wheat disease management in the Xyway fungicide trial at Stillwater, Oklahoma 2024.

TrtFungicideStripe rust (%) Apr 19Stay green (%) May 1Stay green (%) May 9Yield (bu/ac) Jun 19Test weight (lb/bu) June 19
1Untreated Check48.75  a30.0  f2.5  d22.9  d50.2  bcd
2Plain Liquid Fertilizer (10-34-0) @ 6 gallons/A dribble over top of row41.25  a40.0  ef5.0 cd23.3  d50.3  bcd
3Xyway LFR 3.8 + 10-34-0 @ 6 gallons/A dribble over top of row37.5  ab47.5  de7.5  cd24.8  d49.8 bcd
4Xyway LFR 8.9 + 10-34-0 @ 6 gallons/A dribble over top of row12.5  d57.5  cd10.0  bcd34.6  c49.0  d
5Xyway LFR 15.2 + 10-34-0 @ 6 gallons/A dribble over top of row15  cd55.0  d12.5  bc33.9  c50.8  bc
6Xyway LFR 8.9 + 10-34-0 @ 6 gallons/A dribble over top of row fb Adastrio 8 oz/ac + 0.25% v/v NIS @ flag leaf10  d87.5  a75.0  a83.2  a59.9  a
7Plain Fertilizer (11-52-0) 50 lbs/A in-furrow @ planting38.75  a40.0  ef2.5  d24.6  d49.6  bcd
8Xyway LFR (3.8 fl oz) Impregnated Fert GR (11-52-0) 50 lbs/A in-furrow @ planting26.25  bc50.0  de5.0  cd26.2  d49.3  cd
9Xyway LFR (8.9 fl oz) Impregnated Fert GR (11-52-0) 50 lbs/A in-furrow @ planting15  cd60.0  cd12.5  bc36.7  c50.9  bc
10Xyway LFR (15.2 fl oz) Impregnated Fert GR (11-52-0) 50 lbs/A in-furrow @ planting12.5  d70.0  bc17.5  b36.9  c51.0  b
11Xyway LFR (8.9 fl oz) Impregnated Fert GR (11-52-0) 50 lbs/A in-furrow @ planting fb Adastrio 8 oz/ac + 0.25% v/v NIS @ flag leaf16.25  cd75.0  ab70.0  a72.5 b59.7  a
LSD (p=0.05) 12.013.57.65.31.7

Foliar Wheat Disease Management with Fungicides – Oklahoma 2024

Meriem Aoun, Small Grains Pathologist

Department of Entomology & Plant Pathology Oklahoma State University

COOPERATORS: Dr. Meriem Aoun1, Brian Olson1, Tyler Pierson2, and Dr. Amanda de Silva Oliveira2

1Departments of Entomology & Plant Pathology, Oklahoma State University, Stillwater, OK; 2Plant & Soil Science, Oklahoma State University, Stillwater, OK.

PURPOSE:  To determine the efficacy of fungicides for controlling foliar diseases when applied to hard red winter wheat in Oklahoma.

LOCATION:  Entomology & Plant Pathology Research Farm; Stillwater, Oklahoma (Google Maps coordinates:  36.1266690, -97.1047885)

VARIETY: ‘OK Bullet’ hard red winter wheat                    

SOIL TYPE:  Norge loam

PLANTING DATE & RATE:  10-NOV-2023 at 90 lb/ac

FUNGICIDE APPLICATION DATES:

Green up application at Feekes’ growth stage 6 (GS6: 1st node detectable at base of main tiller): 20-MAR-2024

Flag leaf application at Feekes’ growth stage 10.1 (GS 10.1: heads (awns) just starting to emerge from the boot): 17-APR-2024.

TARGET ORGANISMS (DISEASES): P. striiformis (stripe rust), Puccinia triticina (wheat leaf rust), Blumaria graminis f. sp. tritici (wheat powdery mildew), and Zymoseptoria tritici (Septoria leaf blotch)

PLOT DESIGN: Plots were 49 in. (7 rows; 7 in. spacing) by 20 ft, replicated four times in a randomized block design. Data were analyzed using R version 4.1.3.  Mean separation (LSD) test was conducted only if ‘F’ test was significant.

CULTURAL PRACTICES:

Fertilizer: Based on a soil test with a 50 bu/ac yield goal, 150 lbs/ac of 46-0-0 (Urea) and 150 lbs/ac 18-46-0 (Diammonium Phosphate/DAP) dry fertilizer were applied on September 9, 2023. On Feb 7, 2024, a top dress with 50 lbs/ac of 46-0-0 (Urea) was applied.

Herbicide:  None applied

Insecticide:  Gaucho 600 (2.4 fl oz/cwt) applied as a seed treatment to limit barley yellow dwarf

Irrigation:  No irrigation provided

METHOD OF APPLICATION:  Fungicides were applied with a CO2 wheelbarrow sprayer as a broadcast foliar application using flat fan nozzles (8003EVS) spaced 18 inches apart. The sprayer was calibrated to deliver fungicides at a rate of 15 GPA.

DISEASE ASSESSMENT: When sufficient foliar disease was present, plots were evaluated for type of disease and rated for percent infection using modified keys based on, “A Manual of Assessment Keys for Plant Disease. 1971. Clive James. Canada Department of Agriculture Publication No. 1458.” In this rating system, we took the percentage of leaf surface area covered by a disease.

HARVEST METHOD: Plots were harvested with a Wintersteiger Delta small plot combine. Grain weight, test weight, and moisture content were collected from each plot. Grain moisture at harvest was ~ 8% for all plots. The grain yield of the plots was adjusted to 12% moisture.

GENERAL OBSERVATIONS

Fall and winter rains (accumulated rainfall OCT-FEB was 10.9 inches) in Stillwater provided adequate moisture for good wheat growth and development. The accumulated rainfall in spring of 2023 (March – May) was 11.6 inches with the highest levels of moisture recorded in May 2024 (7.5 inch). By early April, the wheat was ahead of schedule, with the flag leaf appearing around two weeks earlier than normal. Low levels of barley yellow dwarf (BYD) infections were present but scattered randomly across the trial. Although BYD may have slightly impacted yield it was not a major concern. 

Stripe rust was severe in April and early May. Stripe rust was first observed on March 31 in Stillwater. On April 17, stripe rust severity reached 20% on average on the untreated check. Stripe rust severity was rated in this trial on April 17, just before the flag leaf application. On May 1st, 2024 (2 weeks after the flag leaf application), stripe rust was rated again and the untreated check showed an average severity of 27.5%. Leaf rust appeared in this trial around the last week of April – early May. On May 1 and May 9, leaf rust ratings were collected with the untreated check showing an average severity of 32.5% and 90.0%, respectively. Powdery mildew was observed in April and May but at low levels (average severity on the untreated check was 1% on April 17 and 10 % on May 1st). The foliage senesced quickly after May 9 and no more ratings could be made. No indication of phytotoxicity by any fungicide treatment was observed. The rainfall in May delayed harvest by a couple of weeks. The plots were harvested on June 19, 2024.

SUMMARY

There were 21 fungicide treatments in this commercial fungicide trial and one untreated check (Table 1). Results from this trial demonstrated the efficacy of most fungicide treatments in managing foliar fungal diseases (primarily stripe rust and leaf rust) (Table1). Stripe rust and leaf rust were significantly lower for most fungicide treatments in comparison to the untreated check. Consequently, most fungicide treatments resulted in higher yield and test weight. Yield (adjusted to 12% moisture) ranged from 51.7 bu/ac to 87.0 bu/ac. Test weight ranged from 56.2 to 62.9 lb/bu. The untreated check had the lowest yield and test weight (Table 2).

Fungicide treatments that were applied at green up only (treatments 2, 3, and 15) were not efficient in controlling rust diseases. Treatments # 4, 12, 13, 11, 18, 8, 6, 10, 21, 17, 9, and 5 were associated with the lowest levels of rust diseases and the highest yields and test weight (Table 1, 2).

Table 1. Fungicide treatments in the commercial fungicide trial at Stillwater, Oklahoma in 2024.

Trt #CompanyTreatment
1CheckUntreated Check
2FMCTopguard 5 fl oz/a + 0.25% v/v NIS @ green up
3FMCAdastrio 3.5 fl oz/a + 0.25% v/v NIS @ green up
4FMCAdastrio 3.5 fl oz/a + 0.25% v/v NIS @ green up fb Adastrio 3.5 fl oz/a + 0.25% v/v NIS @ flag leaf
5FMCAdastrio 3.5 fl oz/a + 0.25% v/v NIS @ green up fb Adastrio 5 fl oz/A + 0.25% v/v NIS @ flag leaf
6FMCTopguard 5 fl oz/a + 0.25% v/v NIS @ green up fb Adastrio 5 fl oz/a + 0.25% v/v NIS @ flag leaf
7FMCTopguard 5 fl oz/a + 0.25% v/v NIS @ green up fb Topguard 5 fl oz/a + 0.25% v/v NIS @ flag leaf
8FMCTopguard 5 fl oz/a + 0.25% v/v NIS @ green up fb Topguard EQ 5 fl oz/a + 0.25% v/v NIS @ flag leaf
9AlbaughMiCrop 5.0 fl oz/a + 0.25% v/v NIS @ green up fb MiCrop 10.0 fl oz/a + 0.25% v/v NIS @ flag leaf
10AlbaughALB4003B 5.0 fl oz/a + 0.25% v/v NIS @ green up fb ALB4003B 10.0 fl oz/a + 0.25% v/v NIS @ flag leaf
11AlbaughALB4010B 3.0 fl oz/a + 0.25% v/v NIS @ green up fb MiCrop 10.0 fl oz/a + 0.25% v/v NIS @ flag leaf
12AlbaughALB4003B + ALB5018 (5.0 fl oz/a + 0.1% v/v) + 0.25% v/v NIS @ green up fb ALB4003B + ALB5018 (10.0 oz/a + 0.1% v/v) + 0.25% v/v NIS @ flag leaf
13AlbaughALB4010B + ALB5018 (3.0 fl oz/a + 0.1% v/v) + 0.25% v/v NIS @ green up fb MiCrop (10.0 fl oz/a) + 0.25% v/v NIS @ flag leaf
14UPLZolera FX 5 fl oz/a + 0.125% v/v NIS @ flag leaf
15UPLEvito 480 SC 1 fl oz/a + 0.125% v/v NIS @ green up
16UPLEvito 480 SC 1 fl oz/a + 0.125% v/v NIS @ green up fb Zolera FX 5 fl oz/a + 0.125% v/v NIS @ flag leaf
17SyngentaAlto 4 fl oz/a + 0.125% v/v NIS @ green up fb Aprovia Ace 9.4 fl oz/a + 0.125% v/v NIS @ flag leaf
18SyngentaAlto 4 fl oz/a + 0.125% v/v NIS @ green up fb Trivapro 13.7 fl oz/a + 0.125% v/v NIS @ flag leaf
19CheckTilt 4.0 fl oz/a + 0.125% v/v NIS @ flag leaf
20BASFNexicor 9 fl oz/a + 0.125 % v/v NIS @ flag leaf
21BASFPriaxor 2 fl oz/a + 0.125 % v/v NIS @ green up fb Sphaerex 4 fl oz/a + Headline 6 fl oz/a + 0.125 % v/v NIS @ flag leaf
22BASFPriaxor 2 fl oz/a + 0.125 % v/v NIS @ green up fb Nexicor 7 fl oz/a + 0.125 % v/v NIS @ flag leaf

Table 2. Summary of foliar wheat disease management at Stillwater, Oklahoma 2024.

Trt #Stripe rust % 04-17-2024Stripe rust % 05-01-2024Leaf rust % 05-01-2024Leaf rust % 05-09-2024Yield (bu/ac) 06-19-2024Test weight (lb/bu) 06-19-2024
120.0  a27.5 ab32.5 a90.0  a51.7  f56.2  i
21.0  de10.0 d20.0 bc82.5  a61.9 de57.2  i
36.8  bcde12.5 cd15.0 bcde87.5  a57.5 ef56.7  i
41.0  de5.0 d5.0 fgh17.5  ef87.0  a62.3  abcd
52.0  de2.5 d5.0 fgh10.0  fgh81.1  a62.3  abcd
62.0  de2.5 d2.5 gh10.0  fgh83.8  a62.2  abcd
71.0  de5.0 d12.5 cdef67.5  b66.2  cd59.5  h
82.0  de7.5 d7.5 efgh20.0  e83.9  a61.7  cde
95.0  bcde5.0 d5.0 fgh20.0  e81.4  a61.7  cde
103.3  cde7.5 d2.5 gh15.0  efg83.0  a61.9  bcd
113.0  cde2.5 d7.8 efgh10.0  fgh84.9 a62.9  a
126.3  bcde7.5 d0.0 h7.5  gh86.2  a62.7  ab
134.0  bcde5.0 d2.5 gh10.0  fgh85.4  a62.6  abc
1413.8  ab12.5 cd15.0 bcde47.5  c67.1 cd60.8  efg
1511.3  abcd32.5 a22.5 b87.5  a56.3  ef56.3  i
1620.0  a25 abc10.0 defg47.5  c71.3  bc60.6  fg
170.8 e7.5 d5.3 fgh5.0  h82.3  a62.1  abcd
185.3  bcde2.5 d2.5 gh5.0  h84.7  a62.6  abc
1921.3  a30.0 a17.5 bcd67.5  b64.8 d60.2  gh
2012.5  abc15.0 bcd13.78 bcdef32.5  d73.8  b62.1  abcd
2112.5  abc12.5 cd2.5 gh12.5  efgh82.9  a62.3  abcd
2218.8  a25.0 abc12.5 cdef30.0  d74.5 b61.5  def
LSD (p= 0.05)10.312.69.19.76.61.0