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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #375529

Research Project: Healthy, Sustainable Pecan Nut Production

Location: Fruit and Tree Nut Research

Title: Evaluation of Miravis Top and Two Phosphite Application Methods to Manage Scab (Venturia Effusa) on Pecan (Carya Illinoinensis) in Georgia

item BRENNEMAN, TIM - University Of Georgia
item Hotchkiss, Michael - Mike
item BROCK, JASON - University Of Georgia
item Bock, Clive

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2020
Publication Date: 12/1/2020
Citation: Brenneman, T.B., Hotchkiss, M.W., Brock, J.H., Bock, C.H. 2020. Evaluation of Miravis Top and Two Phosphite Application Methods to Manage Scab (Venturia Effusa) on Pecan (Carya Illinoinensis) in Georgia. Meeting Abstract. Vol 110: S2.

Interpretive Summary: Abstract Only.

Technical Abstract: The phosphite fungicides Kphite and Phostrol were compared at 2.4, 4.7, 7.0 and 9.4 L/ha to a nonsprayed control and to Miravis Top (1.0 L/ha) applied at 14-day intervals to scab-susceptible pecan cultivars Wichita and Desirable. Single shoots were sprayed to runoff diluted in 935 L/ha water for a total of 10 applications. The two phosphite products provided similar scab control. Some leaf necrosis occurred at the 9.4 L/ha rate but phytotoxicity was minimal at lower rates. At 2.4-7.0 L/ha the phosphite products gave similar leaf scab control to Miravis Top, but on Wichita were more effective at 9.4 L/ha than Miravis Top. Control of scab on fruit showed a rate response using Kphite or Phostrol, but even the 9.4 L/ha rate was less efficacious than the Miravis Top treatment. On Wichita fruit, the 9.4 L/ha rate of phosphite resulted in 72-77% fruit area diseased, whereas fruit receiving the Miravis Top treatment had only 8% area diseased (nonsprayed = 100%). In a separate trial, Kphite (9.4 L/A) was sprayed 7 times at 3-week intervals to the soil around microjet sprinklers under Wichita and Desirable trees prior to irrigation. Scab severity on both leaves and fruit were similar on the treated and nontreated trees. Although phosphites are systemic, soil applications had no effect on scab, even on young trees with small canopies. Foliar sprays of phosphites are highly effective on leaf scab, and applications with commercial sprayers have not resulted in phytotoxicity.