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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #353136

Research Project: Mitigating Alternate Bearing of Pecan

Location: Fruit and Tree Nut Research

Title: Comparing protection afforded by different organic alternatives to conventional fungicides for reducing scab on pecan

Author
item Bock, Clive
item Shapiro Ilan, David
item Wilkins, Bryan - Auburn University
item Wells, Daniel - Auburn University
item Wells, Lenny - University Of Georgia
item Brock, Jason - University Of Georgia
item Hotchkiss, Michael - Mike
item Mizell, Russ - University Of Florida

Submitted to: International Congress of Plant Pathology Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2018
Publication Date: 10/1/2018
Citation: Bock, C.H., Shapiro Ilan, D.I., Wilkins, B., Wells, D.E., Wells, L., Brock, J.H., Hotchkiss, M.W., Mizell, R.F. 2018. Comparing protection afforded by different organic alternatives to conventional fungicides for reducing scab on pecan. International Congress of Plant Pathology Abstracts and Proceedings. 108:S1.154.

Interpretive Summary:

Technical Abstract: Pecan scab (Venturia effusa) is the major yield-limiting disease in the southeastern USA. Although conventional fungicides are available to manage the disease, there is no comparison of organic methods (organically produced nuts attract a higher price). In 2011, 2012, 2014, 2015 and 2016 trees of cv. Desirable were treated with Bordeaux mixture (BM), Compost tea, Sodium Bicarbonate, Serenade, Serenade + Kocide 2000, Sulfur, Nordox 75WG, or Regalia (R). Exact number of sprays depended on the year. Samples of fruit were assessed for severity of scab. Only in 2011, a dry year, did the sulfur treatment have more severe scab compared to any other treatment (F=2.9, P=0.007). The control (C), and the other treatments were not significantly different to each other. In all remaining years, the C had significantly more severe scab compared to some (2012 [F=11.6, P<0.0001], 2014 [F=14.6, P<0.0001] and 2015 [F=14.6, P<0.0001]) or all other treatments (2016 [F=15.5, P<0.0001]). Trees treated with R had less severe scab compared to the C (2012 [C = 9.7%, R = 2.81%], 2014 [C = 70.0%, R = 24.8%], 2015 [C = 22.1%, R = 4.61%] and 2016 [C = 7.18%, R = 3.22%]). BM did significantly reduce scab severity on fruit in three of five years, in 2012 (4.5%), 2015 (3.33%) and 2016 (2.27%) compared to the C. Other treatments were less consistent. Although organic fungicide options reduce scab, using resistant cultivars will be more reliable for organic pecan production in the southeastern USA.