Scope, distribution, and cause of the peanut kernel shrivel (PKS) syndrome: An emerging threat to Australia’s Peanut Industry

Authors: ADORADA, DANTE - University Of Southern Queensland; Dunlap, Christopher; ASH, GAVIN - University Of Southern Queensland

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2024
Publication Date: 6/30/2024
Citation: Adorada, D.L., Dunlap, C.A., Ash, G.J. 2024. Scope, distribution, and cause of the peanut kernel shrivel (PKS) syndrome: An emerging threat to Australia’s Peanut Industry. Agronomy Journal. https://doi.org/10.3390/agronomy14071435.
DOI: https://doi.org/10.3390/agronomy14071435

Interpretive Summary: Fungal plant pathogens are the source of significant yield losses for US farmers. Peanut growers around the world are facing an emerging fungal pathogen that causes the peanuts to shrivel and become unmarketable. The pathogen that causes this disease has not been identified. In collaboration with Australian Scientists, an investigation was performed to identify the causal agent of this disease. This study identified Fusarium oxysporum as the probable causal agent, through its consistent presence in affected peanuts. Understanding the causal agent of this disease will speed the development of control options and provide US peanut growers with better options to control this emerging threat.

Technical Abstract: The cause of peanut kernel shrivel (PKS) syndrome, affecting peanut crops in Australia’s growing regions, is currently unknown. It is estimated that PKS is costing the peanut industry more than AUD 5 M p.a. and is a potential threat to the industry. Previous investigations have ruled out all abiotic factors and most biotic factors as the cause of PKS. This research aimed at investigating the scope, distribution, and cause of the PKS syndrome. The survey showed PKS symptoms to be present in peanut crops in all the growing regions surveyed. Based on our study of culturable microorganisms, there appears to be no clear-cut involvement of plant pathogenic bacteria and fungi; however, Fusarium spp. were revealed as the most prevalent fungi in affected plants. Moreover, the soil metagenomics study revealed Fusarium spp. as the most abundant fungal communities in the soil microbial profile, and they could contribute to the PKS syndrome. The consistent presence observed of the identified Fusarium oxysporum in PKS-affected samples could indicate a role for this pathogen in the syndrome, especially in conjunction with abiotic stressors. The pathogenicity testing of F. oxysporum resulted in very mild PKS symptoms. A separate report suggesting the involvement of phytoplasma in the PKS syndrome raises the possibility of an interplay of biotic factors in the development of this disease. Further investigation is warranted to determine the true cause or causes of this disease.