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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #376449
Research Project: Healthy, Sustainable Pecan Nut Production

Location: Fruit and Tree Nut Research

Title: Efficacy of new chemical fungicides for peach scab control in Georgia, 2019

Author
item BRANNEN, PHILLIP - University Of Georgia
item BREEDEN, SHANE - University Of Georgia
item WARRES, B - University Of Georgia
item WINKLES, J - University Of Georgia
item Bock, Clive
item Hotchkiss, Michael - Mike

Submitted to: Plant Disease Management Reports
Publication Type: Other
Publication Acceptance Date: 1/31/2020
Publication Date: 3/9/2020
Citation: Brannen, P.M., Breeden, S., Warres, B., Winkles, J., Bock, C.H., Hotchkiss, M.W. 2020. Efficacy of new chemical fungicides for peach scab control in Georgia, 2019. Plant Disease Management Reports. 14:PF018.

Interpretive Summary: Efficacy of three fungicides applied were compared for peach scab control on an experimental block of peach trees located at Byron, GA. All treatments were applied with an airblast sprayer at a rate of 73 gallons per acre. Treatment regimens included an untreated control [no fungicides applied], Bravo Weatherstik (chlorothalonil), Bravo Weatherstik (chlorothalonil) with cover sprays of sulfur [commercially accepted, normal spray schedule for peach scab], Miravis (pydiflumetofen) and Miravis Top (pydiflumetofen + difenoconazole). Scab incidence (number of infected fruit) as well as scab severity (number of lesions per fruit) were recorded. Fungicide applications at petal fall, shuck split, shuck off, and 7-10 days after shuck split with Miravis or Miravis Top resulted in complete disease control (zero scab lesions), even ~3 months later. However, the residual efficacy of Bravo Weatherstik was greatly limited by comparison and did not provide significant disease control as compared to the untreated control; this has been observed in previous trials, and the addition of sulfur cover sprays are required for season-long scab control when using chlorothalonil products.

Technical Abstract: Efficacy of three fungicides applied at petal fall to 1% shuck split and shuck split to 10% shuck off, 90% shuck off (5 Apr), and 7-10 days after shuck split (19 Apr) were compared for peach scab control on an experimental block of peach trees located at Byron, GA. The only treatment to receive additional cover sprays (all sulfur) was a full-season spray schedule; the sulfur cover spray dates for this spray regimen were applied on 2 May, 16 May, 30 May, and 13 Jun. All treatments were applied with an airblast sprayer at a rate of 73 gallons per acre. Treatment regimens included an untreated control [no fungicides applied], Bravo Weatherstik (chlorothalonil), Bravo Weatherstik (chlorothalonil) with cover sprays of sulfur [commercially accepted, normal spray schedule for peach scab], Miravis (pydiflumetofen) and Miravis Top (pydiflumetofen + difenoconazole). At commercial maturity (26 Jun), 40 peaches were randomly collected from the two center trees in every plot. Scab incidence (number of infected fruit) as well as scab severity (number of lesions per fruit) were recorded. Fungicide applications at petal fall, shuck split, shuck off, and 7-10 days after shuck split with Miravis or Miravis Top resulted in complete disease control (zero scab lesions), even ~3 months later. However, the residual efficacy of Bravo Weatherstik was greatly limited by comparison and did not provide significant disease control as compared to the untreated control; this has been observed in previous trials, and the addition of sulfur cover sprays are required for season-long scab control when using chlorothalonil products.