Assessment of Pathogenicity of Fungal Pathogen Causing Necrotic Leave Infection of Basella Alba and Control Using Synthetic Metal Complexes

Basella alba is susceptible to various fungal pathogens that cause necrotic leaf infections, leading to significant yield losses. Understanding the mechanisms of pathogenicity in these fungi is crucial for developing effective management strategies. This study aims to assess the pathogenicity of Diaporthe phaseolorum causing necrotic leaf infections in Basella alba and evaluate the effectiveness of synthetic metal complexes for disease control. Leaf samples of B. alba with necrotic lesions were cultured on Potato Dextrose Agar, and isolates were identified through cultural, and molecular methods using 18S rRNA gene sequencing. Pathogenicity was tested using both detached leaf and container-grown trial on healthy B. alba. The infection impacts on growth and disease incidence was also assessed. The inhibitory effects of metal complexes (in millimole and fractions) on spore germination, electrolyte release, and inhibition rates over 20 hours were evaluated. Chlorophyll content, heavy metal accumulation, and environmental pollution indices were analyzed post-treatment. Pathogenicity tests confirmed that infection by D. phaseolorum significantly impacted B. alba growth and disease incidence. Metal complexes inhibited fungal growth effectively, with inhibition rates increasing from 0% to 100% at concentrations of 0.0625 mM and 0.5 mM, respectively. However, CuSO₄ (control) showed phytotoxic effects, causing a 99.15% disease incidence. Greenhouse trials revealed that after one week of treatment, disease incidence decreased by 5.19–34.51%. By the second week, FeL₂SO₄·H₂O (L = Dimethylglyoxime) and CuSO₄ reduced disease incidence to 3.9% and 0%, respectively. Ion release analysis following fungal exposure to FeL₂SO₄·H₂O and CuSO₄ showed the following percentages: Na⁺ (30.14 and 36.21), Ca²⁺ (19.15 and 11.29), and K⁺ (10.81 and 4.16). Chlorophyll content analysis using Arnon’s equation indicated values ranging from 0.1 to 4.6 for chlorophyll a and b before and after infection. Based on the findings of this study, it was concluded that, screened FeL2SO4.H2O: L = DMG (1:2) as better candidate to substitute CuSO4 in the control of D. phaseolorum necrosis in B. alba, due to the toxic effect of CuSO4 to other beneficial organisms in the environment.