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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #307432
Title: Efficacy of Prophyt, a phosphonate fungicide, when combined with other fungicides for control of peach scab in Alabama, 2013

Author
item SIKORA, E - Auburn University
item PITTS, J - Auburn University
item BRANNEN, P - University Of Georgia
item FALL, L - 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: Sikora, E.J., Pitts, J., Brannen, P.M., Fall, L.A., Bock, C.H., Hotchkiss, M.W. 2014. Efficacy of Prophyt, a phosphonate fungicide, when combined with other fungicides for control of peach scab in Alabama, 2013. Plant Disease Management Reports. Rep.8:STF013.

Interpretive Summary: Peach scab affects the marketability of fruit in the southeast US. Fungicides were evaluated for control of scab in the mid-ripening peach variety ‘Ruston Red’ located at Clanton, AL. Treatments were 1) a non-treated control, 2) Bravo Weather Stick, 3) Captan 80, 4) Yellow Jacket Sulfur, 5) Abound, 6) Prophyt, 7) Prophyt + Bravo Weather Stick, 8) Prophyt + Captan 80, 9) and Prophyt + Yellow Jacket Sulfur. Scab incidence and severity were recorded on the day of harvest. Both Abound and Captan reduced scab severity with only two early-season applications. Prophyt did not provide significant suppression of scab, but the combination of Prophyt and chlorothalonil provided substantial efficacy, as compared with other treatments. When Prophyt was combined with sulfur, a numerical improvement in efficacy was also observed. Based on results from this trial, Prophyt, when combined with protectant fungicides, may provide added value for scab management. Additional research is needed to support this premise. Phytototoxicity was not observed with any of the fungicides utilized in this trial.

Technical Abstract: Fungicides were evaluated for control of scab in a mid-ripening peach experimental block (‘Ruston Red’) located at the Auburn University Research Station in Clanton, AL. Chemical formulations were applied with an airblast sprayer (100 gal/A spray volume) at the petal fall and shuck split phenology. Application dates were 6 Apr (petal fall to 1% shuck split) and 15 Apr (shuck split to 10% shuck off). Treatment regimens included 1) a non-treated control, 2) Bravo Weather Stick, 3) Captan 80, 4) Yellow Jacket Sulfur, 5) Abound, 6) Prophyt, 7) Prophyt + Bravo Weather Stick, 8) Prophyt + Captan 80, 9) and Prophyt + Yellow Jacket Sulfur. 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 orchard cultural management was in keeping with peach production methods commonly practiced throughout the Southeast. At full maturity, 40 fruit were harvested from each plot for scab assessments (15 Jul). Scab incidence and severity were recorded on the day of harvest. A critical peak in peach scab spore production and dispersal occurs over the petal fall and shuck split period. Due to heavy rainfall throughout the season, scab infections continued later in the season, as indicated by the high incidence and severity levels that developed, even with fungicide applications. However, both Abound and Captan reduced scab severity with only two early-season applications. Prophyt did not provide significant suppression of scab, but the combination of Prophyt and chlorothalonil provided substantial efficacy, as compared with other treatments. When Prophyt was combined with sulfur, a numerical improvement in efficacy was also observed. Based on results from this trial, Prophyt, when combined with protectant fungicides, may provide added value for scab management. Additional research is needed to support this premise. Phytototoxicity was not observed with any of the fungicides utilized in this trial.