A super absorbent polymer containing copper to control Plenodomus tracheiphilus the causative agent of mal secco disease of lemon

Author: mycolabadmin
9/8/2022
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Summary

Researchers developed a new gel-like material containing copper that can fight a serious fungal disease affecting lemon trees. Unlike traditional copper sprays that wash away and pollute the environment, this new material slowly releases copper directly into the plant’s water-conducting vessels where the disease-causing fungus lives. The gel absorbed water effectively and released copper ions gradually over time, showing much better results than regular copper solutions when tested on infected lemon branches.

Background

Mal secco disease (MSD) of lemon is a destructive tracheomycosis caused by Plenodomus tracheiphilus that affects citrus production, particularly in Mediterranean regions. Copper-based fungicides are commonly used for control but raise environmental concerns due to copper persistence and accumulation in soil and groundwater. Super absorbent polymers (SAPs) have been used in agriculture for water retention and nutrient delivery but not previously for antifungal disease control.

Objective

This study investigated the effectiveness of a super absorbent polymer (SAP) containing copper as a carrier for antifungal compounds to control P. tracheiphilus and mal secco disease in lemon. The research aimed to characterize the copper absorption capacity, release kinetics, and antifungal efficacy of SAP-Cu in both in vitro conditions and naturally infected lemon twigs.

Results

The SAP absorbed approximately 200 times its weight in ionized water and 30 times its weight in 236 mM copper sulfate solution. Maximum copper ion release was achieved within 24 hours, with the SAP releasing about 20% of contained copper ions. SAP-Cu at 236 mM showed 80% mycelial growth inhibition in vitro and significantly reduced P. tracheiphilus viability in naturally infected lemon twigs. ToF-SIMS analysis revealed that copper ions from SAP-Cu were preferentially distributed along xylem vessels rather than uniformly distributed.

Conclusion

This study demonstrates that SAP is an effective carrier for controlled delivery of copper as an antifungal agent against P. tracheiphilus and mal secco disease. The preferential localization of copper within xylem vessels provides enhanced disease control compared to aqueous copper solutions. This innovative formulation represents a promising eco-friendly strategy to reduce environmental copper contamination while maintaining disease control efficacy.

Published in:Frontiers in Microbiology,
Study Type:In vitro and field study,
Source: PMID: 36160225, PMCID: PMC9493267, DOI: 10.3389/fmicb.2022.987056