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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #307431
Title: Efficacy of fungicides for control of scab on a mid-ripening peach variety in middle Georgia, 2013

Author
item BRANNEN, P - University Of Georgia
item FALL, P - University Of Georgia
item Bock, Clive
item Hotchkiss, Michael - Mike

Submitted to: Plant Disease Management Reports
Publication Type: Other
Publication Acceptance Date: 8/5/2014
Publication Date: 8/12/2014
Citation: Brannen, P.M., Fall, P.M., Bock, C.H., Hotchkiss, M.W. 2014. Efficacy of fungicides for control of scab on a mid-ripening peach variety in middle Georgia, 2013. Plant Disease Management Reports. Rep.8:STF015.

Interpretive Summary: Scab reduces the marketable yield of peach in the southeast US. Fungicides were evaluated for control of scab in the mid-ripening peach cultivar ‘Flameprince’ at Byron, GA. Treatments were: (1) a non-treated control, (2) Bravo at petal fall and shuck split, (3) Abound at petal fall and shuck split, (4) Yellow Jacket Sulfur at petal fall and shuck split, (5) Abound at petal fall and Bravo at shuck split, (6) Bravo at petal fall and Abound at shuck split, (7) Abound at petal fall and Yellow Jacket Sulfur at shuck split, (8) Yellow Jacket Sulfur at petal fall and Abound at shuck split, (9) Bravo at petal fall and shuck split followed by Yellow Jacket Sulfur cover sprays (industry standard), and (10) Abound at petal fall and shuck split followed by Yellow Jacket Sulfur cover sprays. Fruit were harvested from each plot and assessed for scab severity. In this trial, although Abound was numerically superior to Bravo when applied at the petal fall and shuck split phenologies, no differences were observed between these two fungicides when they were followed by sulfur cover sprays. The ordering of Abound versus Bravo or Abound versus sulfur did not make a difference in this trial. No phytotoxicity was observed with any treatment.

Technical Abstract: Fungicides were evaluated for control of scab in a mid-ripening peach experimental block (‘Flameprince’) located at the USDA-ARS Fruit and Tree Nut Research Laboratory (Byron, GA). Chemical formulations were applied with an airblast sprayer (100 gal/A spray volume) at each application date: 5 Apr (petal fall to 1% shuck split), 15-16 Apr (shuck split to 10% shuck off), 22 Apr, 3 May, 10 May, 17 May, 24 May, 31 May, 7 Jun, 14 Jun, 21 Jun, 28 Jun, 8 Jul (cover sprays). Treatment regimens included: (1) a non-treated control, (2) Bravo at petal fall and shuck split, (3) Abound at petal fall and shuck split, (4) Yellow Jacket Sulfur at petal fall and shuck split, (5) Abound at petal fall and Bravo at shuck split, (6) Bravo at petal fall and Abound at shuck split, (7) Abound at petal fall and Yellow Jacket Sulfur at shuck split, (8) Yellow Jacket Sulfur at petal fall and Abound at shuck split, (9) Bravo at petal fall and shuck split followed by Yellow Jacket Sulfur cover sprays (industry standard), and (10) Abound at petal fall and shuck split followed by Yellow Jacket Sulfur cover sprays. Four replications of each treatment were applied to a randomized complete block design, with each plot consisting of four trees; the outer two trees in each plot were not utilized for ratings. An unsprayed guard row was left between each treatment row. All cultural management adhered to standard peach production methods commonly practiced throughout the Southeast. At full maturity, 40 fruit were harvested from each plot for scab assessments (11 Jul). Scab incidence and severity were recorded on the day of harvest. Scab symptoms can develop throughout the season from inoculum, but a critical peak in spore production and dispersal occurs during the petal fall and shuck split phenological stages. The application of Abound at petal fall and shuck split has generally provided better efficacy than Bravo (chlorothalonil) or sulfur. However, the addition of cover sprays of sulfur overrides the effect. In this trial, although Abound was numerically superior to Bravo when applied at the petal fall and shuck split phenologies, no differences were observed between these two fungicides when they were followed by sulfur cover sprays. The ordering of Abound versus Bravo or Abound versus sulfur did not make a difference in this trial. No phytotoxicity was observed with any treatment.