Suppression of Pecan Scab by Nickel

Abstract

<jats:p>The economic cost of pecan scab, caused by <jats:italic>Fusicladium effusum</jats:italic> G. Winter, can substantially limit profitability of pecan [<jats:italic>Carya illinoinensis</jats:italic> (Wangenh.) K. Koch] cultivation in humid environments. Laboratory, greenhouse, and field studies found nickel (Ni) to inhibit growth of <jats:italic>F. effusum</jats:italic> and reduce disease severity on fruit and foliage of orchard trees. Nickel was toxic to the fungus in vitro at concentrations applied to orchard trees, and Ni sprays reduced scab severity on foliage of pecan seedlings in greenhouse experiments. Host genotype appears to influence Ni efficacy with fruit tissue of cultivars of intermediate resistance (i.e., ‘Desirable’) being most responsive to treatment and those most susceptible to scab (i.e., ‘Wichita’ and ‘Apache’) being least responsive. Addition of Ni as a nutritional supplement applied in combination with fungicides applied as air-blast sprays to commercial orchards reduced severity of scab on both leaves and fruit depending on cultivar and date of disease assessment (e.g., scab severity on fruit was reduced by 6% to 52% on ‘Desirable’ in an orchard setting). Nickel-supplemented fungicide sprays to ‘Desirable’ trees in commercial orchards also increased fruit weight and kernel filling, apparently from improved disease control. Although the efficacy of Ni was typically much less than that of triphenyltin hydroxide (TPTH), a standard fungicide used in commercial orchards, Ni treatment of tree canopies for increasing tree Ni nutrition slightly lowered disease severity. These studies establish that foliar Ni use in orchards potentially reduces severity of scab on foliage and fruit in scab-prone environments. The inclusion of Ni with fungicides for management of pecan scab might reduce disease severity over that conferred by fungicide alone, especially if targeted cultivars possess at least a moderate degree of scab resistance. Similar benefit from Ni sprays might also occur in host–fungi interactions involving other crops.</jats:p>

Nickel potentiates soybean resistance against infection by Phakopsora pachyrhizi

“…An strong effect of Ni in reducing rust on day lily plants was reported by Wood and Reilly (2007). However, the effect of Ni in reducing ASR severity in the present study was more modest, similar to the results reported for scab on pecan plants (Wood et al , 2012). The present study used a single soybean genotype and one P .…”

“…oxysporum f. sp. lycopersici (Ahmed et al , 2016), pecan– Fusicladium effusum (Wood et al , 2012), day lily– Puccinia hemerocallidis (Wood and Reilly, 2007), and soybean– Microsphaera diffusa (Barcelos et al , 2018), are also negatively affected by Ni.…”

Maize resistance to northern corn leaf blight is potentiated by nickel

“…In the present study, the physiological and biochemical aspects of maize plants sprayed with Ni and infected by E. turcicum were investigated in detail to shed light on the role of this micronutrient in the potentiation of maize resistance against NCLB. The Ni spray reduced NCLB symptoms on maize leaves showing its potential for disease management, as reported for other interactions such as pecan-F. effusum as well as soybean-M. diffusa and soybean-P. pachyrhizi (Barcelos et al, 2018;Einhardt et al, 2020aEinhardt et al, , 2020bWood et al, 2012).…”

“…For instance, severities of scab (Fusicladium effusum) in pecan and powdery mildew (Microsphaera diffusa) and soybean rust (Phakopsora pachyrhizi) in soybean were reduced by Ni (Barcelos et al, 2018;Einhardt et al, 2020aEinhardt et al, , 2020bWood et al, 2012). According to Barcelos et al (2018), lower powdery mildew severity on the leaves of soybean plants sprayed with Ni was linked to its direct effect against conidia and mycelia of M. diffusa over the leaf surface and higher activities of antioxidative enzymes (e.g., catalase, peroxidase, and superoxide dismutase).…”

Nickel-enriched soybean seeds generate plants more resistant to Asian soybean rust

“…Due to its high mobility in the phloem, up to 70% of the Ni present in the aerial part can be translocated to the seeds in the final period of the cycle of the plant (Cataldo et al 1978). Studies have shown significant effects of Ni for the control of many diseases, such as scab in pecan (Wood et al 2012), as well as powdery mildew and ASR in soybean (Barcelos et al 2018;. According to , the foliar application of Ni to soybean plants promoted greater β-1,3-glucanase activity and expression of genes coding for urease, chalcone isomerase and phenylalanine ammonia-lyase, as well lignification of leaf tissues in response to P. pachyrhizi infection.…”