Molecular identification of Fusarium spp causing wilt on Araucaria araucana and its management

Abstract

Five sampling sites of evergreen conifer Araucaria araucana subjected to decline symptoms were randomly selected across the Punjab province, Pakistan. The declined plants with needle discoloration, chlorosis, drying, and partial to complete shoot wilt symptoms were sampled. The estimated highest disease incidence (DI) and disease severity (DS) was 51.8% and 70%, respectively. The most frequently obtained fungal isolates were identified as Fusarium sp. on a morphological basis and Koch's postulates were fulfilled. Once after the confirmation of the pathogen, one representative isolate was selected and sequenced for accurate identification. The characterized isolate showed 100% similarity with F. solani. Different bio-control agents, Systemic acquired resistance, and antifungal chemicals were integrated to manage the diseases effectively. The fungal antagonists, including Aspergillus niger and Trichoderma harzianum, were evaluated for their antifungal potential. A. niger and T. harzianum showed 71.1% and 55.2% mycelial inhibition, respectively. Among four tested fungicides (Aliette, Topsin M, Tiger, and Amistar), Tiger proved to be the most effective, with 88.8% mycelial suppression over control. For SAR, Salicylic acid (SA) was sprayed @ 1mM, and treated plants showed disease severity of up to 10% compared to fungicide-treated plants. This is 1st comprehensive study on Fusarium solani as the etiological agent of A. araucana and its management from Punjab, Pakistan. Keywords: Evergreen conifer, dioecious, disease assessment, morphogenic, fungal antagonists, antifungal