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United States Department of Agriculture

Agricultural Research Service

Research Project: PECAN CULTIVATION AND DISEASE MANAGEMENT

Location: Fruit and Nut Research

Title: Efficacy of fungicides for control of scab on a mid-ripening peach variety in middle Georgia, 2012

Authors
item Brannen, P -
item Bock, Clive
item Hotchkiss, Michael

Submitted to: Plant Disease Management Reports
Publication Type: Other
Publication Acceptance Date: August 30, 2013
Publication Date: August 30, 2013
Citation: Brannen, P.M., Bock, C.H., Hotchkiss, M.W. 2013. Efficacy of fungicides for control of scab on a mid-ripening peach variety in middle Georgia, 2012. Plant Disease Management Reports. 7:STF021 http://www.plantmanagementnetwork.org/pub/trial/pdmr/.

Interpretive Summary: Various different fungicides were evaluated for control of peach scab in a mid-ripening experimental peach block (‘Flameprince’) located at the USDA-ARS Fruit and Tree Nut Research Laboratory (Byron, GA). Fungicides were applied on a weekly basis from 3 Apr to 22 Jun. Treatment regimens included a non-treated control, two applications of Bravo Weather Stik FL (petal fall and shuck split) followed by Yellow Jacket Sulfur cover sprays (chemical standard), two applications of Abound (petal fall and shuck split) followed by Yellow Jacket Sulfur cover sprays, Yellow Jacket Sulfur at all application timings, Bravo at petal fall, Bravo at shuck split, Abound at petal fall, Abound at shuck split, Bravo at petal fall and shuck split, and Abound at petal fall and shuck split. Scab severity was moderate on the non-treated control in this trial. All full-season spray sprays suppressed scab, but two applications of Abound at petal fall and shuck split resulted in near equivalent control to that of Abound at petal fall and shuck split followed by Yellow Jacket Sulfur cover sprays. The significant advantage of azoxystrobin is likely related to its antisporulent activity, as well as potential for systemic movement. The results suggest that two applications of Abound at petal fall and shuck split can be efficaceous in controlling scab.

Technical Abstract: Fungicides were evaluated for control of scab in a mid-ripening experimental peach block (‘Flameprince’) located at the USDA-ARS Fruit and Tree Nut Research Laboratory (Byron, GA). Chemical formulations were applied at each application date: 3 Apr (petal fall to 1% shuck split), 10 Apr (shuck split to 10% shuck off), 27 Apr, 11 May, 18 May, 25 May, 1 Jun, 8 Jun, 15 Jun, and 22 Jun (cover sprays). Treatment regimens included a non-treated control, two applications of Bravo Weather Stik FL (petal fall and shuck split) followed by Yellow Jacket Sulfur cover sprays (chemical standard), two applications of Abound (petal fall and shuck split) followed by Yellow Jacket Sulfur cover sprays, Yellow Jacket Sulfur at all application timings, Bravo at petal fall, Bravo at shuck split, Abound at petal fall, Abound at shuck split, Bravo at petal fall and shuck split, and Abound at petal fall and shuck split. Scab severity was moderate on the non-treated control in this trial; all full-season spray regimens were effective for suppression of scab, but two applications of Abound at petal fall and shuck split resulted in near equivalent control to that of Abound at petal fall and shuck split followed by Yellow Jacket Sulfur cover sprays. For Bravo, the shuck split and combination of petal fall and shuck split applications significantly reduced scab severity, but the petal fall application alone did not suppress disease. Abound, on the other hand, significantly and profoundly suppressed scab with petal fall, shuck split and the combination of both applications. The significant advantage of azoxystrobin is likely related to its antisporulent activity, as well as potential for systemic movement. With a protective contact fungicide such as chlorothalonil (Bravo) or sulfur, the early application would have been ineffective as shucks opened to expose susceptible fruit. Use of sulfur alone, though relatively efficacious, allowed for disease severity and incidence levels that would have resulted in downgraded fruit relative to USDA standards. The results suggest that two applications of Abound at petal fall and shuck split can be efficaceous in controlling scab.

Last Modified: 9/22/2014
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