The Sprout Regulating Compound 1,4-Dimethylnaphthalene Exhibits Fungistatic Activity

Michael Campbell,Kara Dobson,Rachael Adams,Jessica Till,Veronica Stefanick,Emily Dobry,Abubaker Haroun Mohamed Adam

doi:10.14302/issn.2639-3166.jar-18-2502

Michael Campbell, Kara Dobson + Show 5 more

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https://doi.org/10.14302/issn.2639-3166.jar-18-2502

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Abstract

The compound 1,4-dimethylnaphthalene, originally isolated from dormant potatoes, is currently in use as a commercial sprout inhibitor. Growers and processors report a reduction in fungal infections in potatoes treated with DMN resulting in increased yields. To assess the effects of DMN on fungal growth a culture of Fusarium oxysporum was isolated from potato tubers and identified via DNA fingerprinting using the 18ITS ribosomal region. Growth of F. oxysporum was inhibited by 31% after four days of exposure to DMN but overall rate of spore germination was not affected by DMN treatment. The growth of additional fungi, including Alternaria alternata, Aspergillus niger, Epicoccum nigrum, Gnomoniopsis smithogilvyi, Phoma medicaginis, and Pythium ultimum was inhibited by DMN as was suppression of sporulation in A. niger. These results suggest that DMN is fungistatic at the application levels examined.

Highlights

Harvested potatoes are often treated with sprout regulators to prolong storage
The average size for Fusarium mycelia in the controls was 9.8 ± 0.7 cm while exposure to dimethyl naphthalene (DMN) resulted in an average growth size to 3.0 ± 0.5 cm
While no polycyclic aromatic hydrocarbon (PAH) has been shown to inhibit the growth of Fusarium, mixtures of hydrophobic oils from clove and lemon grass have been shown to decrease the growth of F. oxysporum sp

Summary

Introduction

Harvested potatoes are often treated with sprout regulators to prolong storage. The naturally occurring volatile carbon compound, 1,4 dimethyl naphthalene (DMN), is an effective sprout control agent when applied to harvested potato tubers [1,7,16]. Growers who utilize DMN demonstrate reduction of potato sprout growth, prolonged storage, and often see a reduction in product loss due to decrease in fungal pathogens. It is unclear if the reduction of disease in storage is a function of DMN directly on pathogens or if DMN induces a response in tubers that increases pathogen resistance. Gene expression analysis on potato tubers treated with DMN did reveal an increase in genes associated with pathogen response [3] but the interaction of DMN directly with fungal pathogens has been poorly assessed

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