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Phenology-Based Applications of Biofungicides and Sulfur with an Intelligent Sprayer for Management of Grape Powdery Mildew

Brent W. Warneke, Lloyd L. Nackley, Jay W. Pscheidt
Am J Enol Vitic.  2026  77: 0770017  ; DOI: 10.5344/ajev.2026.26008

Article Figures & Data

Figures

  • Two timelines compare sulfur and biological fungicide sequences applied from bloom through veraison with assessment periods. Two timelines labeled A and B link fungicide application sequences with the grapevine stages Bloom and Veraison from May through September. In A, the S or B or S trial regime applies Sulfur at 5.6 kilograms per hectare around the beginning of Bloom, followed by Biological fungicides during Bloom, and Sulfur at 5.6 kilograms per hectare from later Bloom through Veraison. In B, the B or S or B trial regime applies Biological fungicides around the beginning of Bloom, followed by Sulfur at 5.6 kilograms per hectare during Bloom, and Biological fungicides from later Bloom through Veraison. In both timelines, Leaf disease assessments extend from June through late July, and a curved arrow labeled Cluster assessment points to Veraison in August.
    Figure 1

    Schematic of fungicide applications (colored boxes), general phenology (within timeline), and data acquisition timing (below timeline) during the (A) 2021 sulfur–biological fungicide–sulfur (S/B/S) study and (B) 2021 to 2023 biological fungicide–sulfur–biological fungicide (B/S/B) studies. In the S/B/S study, micronized sulfur was applied from BBCH 17 to BBCH 64, biological fungicides were applied from BBCH 65 to BBCH 75, then micronized sulfur applications were resumed until BBCH 81; in the B/S/B studies, biological fungicides were applied from BBCH 17 to BBCH 64, micronized sulfur was applied from BBCH 65 to BBCH 75, then biological fungicide applications were resumed until BBCH 81.

  • Two line graphs show spray volume and pesticide quantity across sulfur, biological fungicide, and resumed sulfur applications. Two line graphs labeled A and B plot 12 application dates from 14 May through 11 Aug across three periods labeled Sulfur, Biologicals, and Sulfur, with vertical lines marking the transitions on 4 June and 12 July. The four series are Serenade A S O intelligent, Serenade A S O standard, Aviv intelligent, and Aviv standard. In A, the vertical axis is labeled liters per hectare and ranges from 100 to 600. During the first Sulfur period, all series remain near 500 to 530 liters per hectare. At the transition to Biologicals, both intelligent series decrease sharply to approximately 330 liters per hectare, then gradually rise to approximately 375 liters per hectare, while both standard series remain near 490 to 520 liters per hectare. When Sulfur resumes, all four series converge near 520 to 550 liters per hectare. In B, the vertical axis is labeled Product per hectare and ranges from 0 to 12. All series begin near 6 to 7 and decrease to approximately 5.5 before the Biologicals period. During Biologicals, Serenade A S O intelligent and Serenade A S O standard remain near 1 and 1.3, Aviv intelligent remains near 7, and Aviv standard remains near 10 to 10.5. When Sulfur resumes, all four series converge near 5.6 to 5.8 through 11 Aug. All values are approximated.
    Figure 2

    Spray volume (A) and pesticide quantity applied (B) on each application date in the 2021 sulfur–biological fungicide–sulfur (S/B/S) trial (5.6 kg/ha micronized sulfur applied from BBCH 17 to BBCH 64, biological fungicides then applied from BBCH 65 to BBCH 75, then 5.6 kg/ha micronized sulfur applications resumed until veraison [BBCH 81]). Vertical lines indicate the cutoff when transitioning between biological fungicides and sulfur in the program, and floating labels indicate the products used in the respective panels. Intelligent treatments were applied at 125 mL/m3 of grape canopy. Aviv contains Bacillus subtilis strain IAB/BS03 (0.08%) as the active ingredient (AI) and Serenade ASO contains B. subtilis strain QST 713 (1.34%) as the AI.

  • Two line graphs compare spray volume and pesticide quantity across biological, sulfur, and resumed biological applications. Two line graphs labeled A and B show values by application date from 14 May through 11 Aug. Vertical lines separate the initial Biologicals period, the Sulfur period, and the resumed Biologicals period. The series are LifeGard intelligent, LifeGard standard, Theia intelligent, and Theia standard. In A, the vertical axis shows liters per hectare. During the initial Biologicals period, the intelligent treatments rise from approximately 125 to 250 liters per hectare, while the standard treatments remain near 470 to 500. During Sulfur applications, all treatments converge near 520 to 540. After Biologicals resume, LifeGard intelligent and Theia intelligent decrease to approximately 375 to 395, while LifeGard standard remains near 495 to 510 and Theia standard remains near 510 to 535. In B, the vertical axis shows Product per hectare in grams. During the initial Biologicals period, LifeGard treatments remain below 250 grams, Theia intelligent rises from approximately 1200 to 1800 grams, and Theia standard ranges from approximately 3500 to 4300 grams. During Sulfur applications, all treatments converge near 5500 to 5750 grams. After Biologicals resume, LifeGard treatments return below 250 grams, Theia intelligent ranges from approximately 2700 to 2850 grams, and Theia standard ranges from approximately 3700 to 3900 grams. All values are approximated.
    Figure 3

    Spray volume (A) and pesticide quantity applied (B) on each application date in the 2021 biological fungicide–sulfur–biological fungicide (B/S/B) trial (biological fungicides applied from BBCH 17 to BBCH 64, 5.6 kg/ha micronized sulfur then applied from BBCH 65 to BBCH 75, then biological fungicide applications resumed until veraison [BBCH 81]). Vertical lines indicate the cutoff when transitioning between biological fungicides and sulfur in the program, and floating labels indicate the products used in the respective panels. Intelligent treatments were applied at 125 mL/m3 of grape canopy. LifeGard contains Bacillus mycoides isolate J (40%) as the active ingredient (AI) and Theia contains Bacillus subtilis strain AFS032321 (100%) as the AI.

  • Two line graphs compare 2022 LifeGard spray volume and product quantity during biological, sulfur, and resumed biological use. Two line graphs labeled A and B show values by application date from 25 May through 17 Aug. Vertical lines separate the initial LifeGard period, the Sulfur period, and the resumed LifeGard period. The series are Sulfur during bloom, LifeGard standard, LifeGard Intelligent High, and LifeGard Intelligent Low. In A, the vertical axis shows liters per hectare. Before Sulfur applications, LifeGard standard remains near 575 to 610 liters per hectare, while LifeGard Intelligent High rises from approximately 90 to 390 and LifeGard Intelligent Low rises from approximately 75 to 265. During Sulfur applications, the treatments converge near 635 to 660 liters per hectare. After LifeGard resumes, LifeGard standard remains near 615 to 640, LifeGard Intelligent High ranges from approximately 450 to 480, and LifeGard Intelligent Low ranges from approximately 355 to 370. In B, the vertical axis shows Product per hectare. Before Sulfur applications, LifeGard standard remains near 195 to 205 grams, LifeGard Intelligent High rises from approximately 35 to 130 grams, and LifeGard Intelligent Low rises from approximately 25 to 90 grams. During Sulfur applications, all treatments remain near 7 to 8 kilograms per hectare. After LifeGard resumes, LifeGard standard ranges from approximately 210 to 215 grams, LifeGard Intelligent High ranges from approximately 150 to 160 grams, and LifeGard Intelligent Low ranges from approximately 120 to 125 grams. All values are approximated.
    Figure 4

    Spray volume (A) and pesticide quantity applied (B) on each application date in the 2022 LifeGard biological fungicide–sulfur–biological fungicide (B/S/B) trial (biological fungicides applied from BBCH 17 to BBCH 64, 5.6 kg/ha micronized sulfur then applied from BBCH 65 to BBCH 75, then biological fungicide applications resumed until veraison [BBCH 81]). Vertical lines indicate the cutoff when transitioning between biological fungicides and sulfur in the program, and floating labels indicate the products used in the respective panels. Intelligent High and Low sprayer treatments were applied at 125 and 62.5 mL/m3 of grape canopy, respectively. LifeGard contains Bacillus mycoides isolate J (40%) as the active ingredient.

  • Two line graphs compare 2023 LifeGard spray volume and product quantity during biological, sulfur, and resumed biological use. Two line graphs labeled A and B show values by application date from 22 May through 7 Aug. Vertical lines separate the initial LifeGard period, the Sulfur period, and the resumed LifeGard period. The series are Sulfur during bloom, LifeGard standard, LifeGard Intelligent High, and LifeGard Intelligent Low. In A, the vertical axis shows liters per hectare. Before Sulfur applications, LifeGard standard remains near 530 to 575 liters per hectare, LifeGard Intelligent High rises from approximately 175 to 365, and LifeGard Intelligent Low rises from approximately 115 to 275. During Sulfur applications, all treatments converge near 575 to 595 liters per hectare. After LifeGard resumes, LifeGard standard remains near 560 to 570, LifeGard Intelligent High ranges from approximately 410 to 425, and LifeGard Intelligent Low ranges from approximately 340 to 355. In B, the vertical axis shows Product per hectare. Before Sulfur applications, LifeGard standard remains near 180 grams, LifeGard Intelligent High rises from approximately 60 to 120 grams, and LifeGard Intelligent Low rises from approximately 40 to 90 grams. During Sulfur applications, all treatments remain near 7 to 8 kilograms per hectare. After LifeGard resumes, LifeGard standard remains near 190 grams, LifeGard Intelligent High ranges from approximately 135 to 145 grams, and LifeGard Intelligent Low ranges from approximately 115 to 120 grams. All values are approximated.
    Figure 5

    Spray volume (A) and pesticide quantity applied (B) on each application date in the 2023 LifeGard biological fungicide–sulfur–biological fungicide (B/S/B) trial (biological fungicides applied from BBCH 17 to BBCH 64, 5.6 kg/ha micronized sulfur then applied from BBCH 65 to BBCH 75, then biological fungicide applications resumed until veraison [BBCH 81]). Vertical lines indicate the cutoff when transitioning between biological fungicides and sulfur in the program, and floating labels indicate the products used in the respective panels. Intelligent High and Low sprayer treatments were applied at 125 and 62.5 mL/m3 of grape canopy, respectively. LifeGard contains Bacillus mycoides isolate J (40%) as the active ingredient.

  • Two line graphs compare 2022 Theia spray volume and product quantity during biological, sulfur, and resumed biological use. Two line graphs labeled A and B show values by application date from 25 May through 17 Aug. Vertical lines separate the initial Theia period, the Sulfur period, and the resumed Theia period. The series are Sulfur during bloom, Theia standard, Theia Intelligent High, and Theia Intelligent Low. In A, the vertical axis shows liters per hectare. Before Sulfur applications, Theia standard remains near 570 to 600 liters per hectare, Theia Intelligent High rises from approximately 105 to 390, and Theia Intelligent Low rises from approximately 75 to 275. During Sulfur applications, all treatments converge near 625 to 650 liters per hectare. After Theia resumes, Theia standard ranges from approximately 600 to 620, Theia Intelligent High ranges from approximately 455 to 470, and Theia Intelligent Low remains near 370 to 380. In B, the vertical axis shows Product per hectare in kilograms. Before Sulfur applications, Theia standard ranges from approximately 3.7 to 4.7 kilograms, Theia Intelligent High rises from approximately 0.9 to 2.5 kilograms, and Theia Intelligent Low rises from approximately 0.6 to 1.8 kilograms. During Sulfur applications, all treatments remain near 6.7 to 7.3 kilograms. After Theia resumes, Theia standard remains near 4 kilograms, Theia Intelligent High remains near 3 kilograms, and Theia Intelligent Low remains near 2.4 kilograms. All values are approximated.
    Figure 6

    Spray volume (A) and pesticide quantity applied (B) on each application date in the 2022 Theia biological fungicide–sulfur–biological fungicide (B/S/B) trial (biological fungicides applied from BBCH 17 to BBCH 64, 5.6 kg/ha micronized sulfur then applied from BBCH 65 to BBCH 75, then biological fungicide applications resumed until veraison [BBCH 81]). Vertical lines indicate the cutoff when transitioning between biological fungicides and sulfur in the program, and floating labels indicate the products used in the respective panels. Intelligent High and Low sprayer treatments were applied at 125 and 62.5 mL/m3 of grape canopy, respectively. Theia contains Bacillus subtilis strain AFS032321 (100%) as the active ingredient.

  • Two line graphs compare 2023 Theia spray volume and product quantity during biological, sulfur, and resumed biological use. Two line graphs labeled A and B show values by application date from 22 May through 7 Aug. Vertical lines separate the initial Theia period, the Sulfur period, and the resumed Theia period. The series are Sulfur during bloom, Theia standard, Theia Intelligent High, and Theia Intelligent Low. In A, the vertical axis shows liters per hectare. Before Sulfur applications, Theia standard remains near 545 to 575 liters per hectare, Theia Intelligent High rises from approximately 175 to 350, and Theia Intelligent Low rises from approximately 110 to 250. During Sulfur applications, all treatments converge near 575 to 600 liters per hectare. After Theia resumes, Theia standard remains near 580 to 590, Theia Intelligent High remains near 400 to 415, and Theia Intelligent Low remains near 340 to 355. In B, the vertical axis shows Product per hectare in kilograms. Before Sulfur applications, Theia standard decreases from approximately 4.5 to 3.7 kilograms, Theia Intelligent High rises from approximately 1.5 to 2.3 kilograms, and Theia Intelligent Low rises from approximately 0.9 to 1.7 kilograms. During Sulfur applications, all treatments remain near 6.4 to 6.9 kilograms. After Theia resumes, Theia standard remains near 3.9 kilograms, Theia Intelligent High remains near 2.7 to 2.8 kilograms, and Theia Intelligent Low remains near 2.3 to 2.4 kilograms. All values are approximated.
    Figure 7

    Spray volume (A) and pesticide quantity applied (B) on each application date in the 2023 Theia biological fungicide–sulfur–biological fungicide (B/S/B) trial (biological fungicides applied from BBCH 17 to BBCH 64, 5.6 kg/ha micronized sulfur then applied from BBCH 65 to BBCH 75, then biological fungicide applications resumed until veraison [BBCH 81]). Vertical lines indicate the cutoff when transitioning between biological fungicides and sulfur in the program, and floating labels indicate the products used in the respective panels. Intelligent High and Low sprayer treatments were applied at 125 and 62.5 mL/m3 of grape canopy, respectively. Theia contains Bacillus subtilis strain AFS032321 (100%) as the active ingredient.

Tables

  • Table 1

    Area under disease progress curve (AUDPC, leaf disease) and percent infected berries from the sulfur–biological fungicide–sulfur (S/B/S)a intelligent sprayer trial in 2021.

    TreatmentbRatecAUDPCdPercent infected berries
    UntreatedUntreated2964 (2916-3012) A74.0 (68.0-79.2) A
    Aviv intelligent887 mL/379 L2266 (2081-2451) B13.8 (10.7-17.7) B
    Aviv standard887 mL/379 L2231 (1982-2480) B16.1 (12.5-20.4) B
    Serenade ASO intelligent9.3 L/ha1974 (1552-2396) B14.6 (11.3-18.7) B
    Serenade ASO standard9.3 L/ha2236 (2004-2467) B18.2 (14.2-23.0) B

    • ↵a5.6 kg/ha micronized sulfur applied from BBCH 17 to BBCH 64, biological fungicides then applied from BBCH 65 to BBCH 75, then 5.6 kg/ha micronized sulfur applications resumed until veraison (BBCH 81).

    • ↵bAviv contains Bacillus subtilis strain IAB/BS03 (0.08%) as the active ingredient (AI) and Serenade ASO contains B. subtilis strain QST 713 (1.34%) as the AI.

    • ↵cAll treatments applied at 552 kPa; intelligent sprayer treatments applied at 125 mL/m3 of grape canopy.

    • ↵dEstimates are followed by asymptotic 95% confidence intervals in parentheses. Treatments followed by different letters are statistically different from each other, marginal means contrast (p ≤ 0.05) with p values adjusted using Tukey’s method.

  • Table 2

    Area under disease progress curve (AUDPC, leaf disease) and percent infected berries from the biological fungicide–sulfur–biological fungicide (B/S/B)a intelligent sprayer trial in 2021.

    TreatmentbRatecAUDPCdPercent infected berries
    UntreatedUntreated2969 (2753-3184) A75.2 (69.5-80.2) A
    LifeGard intelligent128 g/379 L741 (526-957) B9.8 (7.5-12.7) B
    LifeGard standard128 g/379 L706 (491-922) B9.1 (7.0-11.8) BC
    Theia intelligent3.4 kg/ha661 (445-876) B7.5 (5.7-9.7) BC
    Theia standard3.4 kg/ha417 (202-633) B5.5 (4.2-7.3) C

    • ↵aBiological fungicides applied from BBCH 17 to BBCH 64, 5.6 kg/ha micronized sulfur then applied from BBCH 65 to BBCH 75, then biological fungicide applications resumed until veraison (BBCH 81).

    • ↵bLifeGard contains Bacillus mycoides isolate J (40%) as the active ingredient (AI) and Theia contains Bacillus subtilis strain AFS032321 (100%) as the AI.

    • ↵cAll treatments applied at 552 kPa; intelligent sprayer treatments applied at 125 mL/m3 of grape canopy.

    • ↵dEstimates are followed by asymptotic 95% confidence intervals in parentheses. Treatments followed by different letters are statistically different from each other, marginal means contrast (p ≤ 0.05) with p values adjusted using Tukey’s method.

  • Table 3

    Area under disease progress curve (AUDPC, leaf disease) and percent infected berries from LifeGard biological fungicide intelligent sprayer trials in 2022 and 2023.

    TreatmentaRateb20222023
    AUDPCcPercent infected berriesAUDPCPercent infected berries
    UntreatedUntreated2658 (2470-2846) A99.5 (99.2-99.7) A2351 (2164-2539) A67.2 (58.5-74.9) A
    Sulfur bloom only (all plots)Sulfur 5.6 kg/ha2162 (1974-2350) B77.2 (69.9-83.2) BC1856 (1668-2044) B44.4 (35.5-53.8) B
    LifeGard standard128 g/379 L2122 (1934-2310) B74.7 (67.0-81.2) C1816 (1628-2004) B27.1 (20.3-35.1) C
    LifeGard Intelligent High128 g/379 L1980 (1792-2168) B85.8 (80.6-89.8) B1674 (1486-1861) B43.7 (34.8-53.1) B
    LifeGard Intelligent Low128 g/379 L2079 (1891-2267) B83.5 (77.6-88.0) BC1773 (1585-1961) B32.2 (24.5-40.8) BC

    • ↵aLifeGard contains Bacillus mycoides isolate J (40%) as the active ingredient.

    • ↵bAll treatments applied at 552 kPa; Intelligent High and Low sprayer treatments applied at 125 and 62.5 mL/m3 of grape canopy, respectively. Treatments were mixed at the rate indicated if the sprayer was used in standard mode. Actual rates applied by the intelligent sprayer system were lower due to the lower volume applied in intelligent mode.

    • ↵cEstimates are followed by asymptotic 95% confidence intervals in parentheses. Treatments followed by different letters are significantly different from each other, marginal means contrast (p ≤ 0.05) with p values adjusted using Tukey’s method.

  • Table 4

    Area under disease progress curve (AUDPC, leaf disease) and percent infected berries from Theia biological fungicide intelligent sprayer trials in 2022 and 2023.

    TreatmentaRateb20222023
    AUDPCcPercent infected berriesAUDPCPercent infected berries
    UntreatedUntreated2630 (2343-2916) A98.8 (98.1-99.3) A2284 (1998-2571) A49.7 (38.3-61.1) A
    Sulfur bloom only (all plots)Sulfur 5.6 kg/ha2204 (1917-2490) B78.8 (70.0-85.5) B1858 (1572-2145) B46.5 (35.3-58.0) A
    Theia standard3.4 kg/ha + sulfur 5.6 kg/ha1599 (1313-1885) D67.8 (56.9-77.0) B1254 (967-1540) D20.8 (14.1-29.5) B
    Theia Intelligent High3.4 kg/ha + sulfur 5.6 kg/ha1954 (1667-2240) BC70.8 (60.4-79.5) B1608 (1322-1895) BC27.9 (19.5-38.1) B
    Theia Intelligent Low3.4 kg/ha + sulfur 5.6 kg/ha1901 (1615-2187) C79.8 (71.3-86.3) B1556 (1269-1842) C21.2 (14.5-30.0) B

    • ↵aTheia contains Bacillus subtilis strain AFS032321(100%) as the active ingredient.

    • ↵bAll treatments applied at 552 kPa; Intelligent High and Low sprayer treatments applied at 125 and 62.5 mL/m3 of grape canopy, respectively. Treatments were mixed at the rate indicated if the sprayer was used in standard mode. Actual rates applied by the intelligent sprayer system were lower due to the lower volume applied in intelligent mode.

    • ↵cEstimates are followed by asymptotic 95% confidence intervals in parentheses. Treatments followed by different letters are significantly different from each other, marginal means contrast (p ≤ 0.05) with p values adjusted using Tukey’s method.

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Phenology-Based Applications of Biofungicides and Sulfur with an Intelligent Sprayer for Management of Grape Powdery Mildew
Brent W. Warneke, Lloyd L. Nackley, Jay W. Pscheidt
Am J Enol Vitic.  2026  77: 0770017  ; DOI: 10.5344/ajev.2026.26008
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