Influence of nickel on severity of pecan scab

Authors: Wood, Bruce; Reilly, Charles; Bock, Clive; Hotchkiss, Michael - Mike

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2011
Publication Date: 6/1/2011
Citation: Wood, B.W., Reilly, C.C., Bock, C.H., Hotchkiss, M.W. 2011. Influence of nickel on severity of pecan scab. Phytopathology. 101:S193.

Interpretive Summary: Pecan scab (caused by Fusicladium effusum) is a major factor limiting profitability of pecan (Carya illinoinensis) in humid environments. The effect of nickel (Ni) on the severity of pecan scab was examined in both field and lab studies from 2005-2010. Application of Ni sprays to foliage in tree canopies reduced subsequent scab severity. Host genotype influenced efficacy - those most resistant to scab (‘Desirable’) were most responsive to Ni treatment and those most susceptible (‘Wichita’ and ‘Apache’) were least responsive to Ni treatment. Addition of Ni to fungicide treatments delivered by air-blast sprayers to commercial orchards reduced the severity of scab disease on fruit by 6-52%, depending on cultivar. Ni augmented fungicide sprays on ‘Desirable’ also increased fruit weight and kernel filling. Ni was toxic to the fungus both in vitro and in vivo, but was not as efficacious as triphenyltin hydroxide, a standard fungicide used in commercial orchards. These studies establish that Ni can provide some protection against pecan scab when used alone at high concentration or when combined at lower concentration with conventional pecan fungicides.

Technical Abstract: Pecan scab, caused by Fusicladium effusum, is a major factor limiting profitability of pecan (Carya illinoinensis) in humid environments. The effect of nickel (Ni) on the severity of pecan scab was examined in both field and lab studies in 2005 to 2010. Application of Ni sprays to foliage in tree canopies appeared to reduce subsequent scab severity. Host genotype influenced efficacy – those most resistant to scab (‘Desirable’) were most responsive to Ni treatment and those most susceptible (‘Wichita’ and ‘Apache’) were least responsive to Ni treatment. Addition of Ni to fungicide treatments delivered by air-blast sprayers to commercial orchards reduced the severity of scab disease on fruit by 6-52%, depending on cultivar. Ni augmented fungicide sprays on ‘Desirable’ also increased fruit weight and kernel filling. Ni was toxic to the fungus both in vitro and in vivo, but was not as efficacious as triphenyltin hydroxide, a standard fungicide used in commercial orchards. These studies establish that Ni can provide some protection against pecan scab when used alone at high concentration or when combined at lower concentration with conventional pecan fungicides. Protection appears to be both indirect via enhancement of host resistance, and direct via toxicity to the scab fungus.