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Widespread use of plant protection agents in agriculture is a major cause of pollution. Apart from active ingredients, the environmental impact of auxiliary synthetic polymers should be minimized if they are highly persistent. An alternative to synthetic polymers is the use of natural polysaccharides, which are abundant and biodegradable. In this study, we explore pectin microgels functionalized with anchor peptides (P‐MAPs) to be used as an alternative biobased pesticide delivery system. Using copper as the active ingredient, P‐MAPs effectively prevented infection of grapevine plants with downy mildew under semi‐field conditions on par with commercial copper pesticides. By using anchor peptides, the microgels tightly bind to the leaf surface, exhibiting excellent rain fastness and prolonged fungicidal activity. Finally, P‐MAPs are shown to be easily degradable by enzymes found in nature, demonstrating their negligible long‐term impact on the environment. [ABSTRACT FROM AUTHOR]

The development of efficient and environmentally friendly plant protection systems is one of the major challenges for a sustainable agriculture of the future. Citrus canker caused by the pathogen Xanthomonas citri subsp. citri (X. citri) affects all cultivated citrus species worldwide and is responsible for enormous economic losses and restrictions in international trade. Currently used commercial copper‐based formulations are the origin of contamination for soil and groundwater, affecting local ecosystems and human health. A copper‐free sustainable microgel‐based plant protection system able to efficiently combat X. citri is developed. Microgels decorated with anchor peptides exhibit strong non‐covalent attachment to the surface of orange leaves and have the ability to release hexyl gallate, which inhibits the growth and spreading of pathogens. The tailored design of the microgel network allows high loadings of hexyl gallate (up to 40 wt.%) and a controlled release of gallates from microgels that provide long‐term protection. The antibacterial activity of the hexyl gallate‐loaded microgels is demonstrated by various in vitro assays as well as on orange plants in greenhouse settings. The experimental results suggest that the developed sustainable microgel‐based plant protection system for citrus trees allows efficient abatement of X. citri and reduces environmental pollution caused by copper formulations. [ABSTRACT FROM AUTHOR]

This work focuses on the pH‐triggered disassembly of supramacromolecular microgels, which are composed of the temperature‐responsive poly(N‐vinylcaprolactam) (PVCL) and the natural polyphenol tannic acid (TA). A systematic investigation of the microgel formation demonstrates that a retarded addition of tannic acid during semi‐batch precipitation polymerization influences the yield, chemical composition, and properties of the microgels to a great extent. Microgel properties, such as size, deformability, and chemical stability, can be easily tuned by varying the ratio between both building blocks PVCL and TA. Finally, the pH‐triggered disassembly of supramacromolecular microgels at different pH and temperatures demonstrates that their chemical structure can precisely control the degradation profile. Temperatures lower than the volume phase transition temperature (VPTT) of PVCL (T < 32 °C) and a pH > 10 result in a complete disassembly of the microgels into PVCL chains and TA due to the destruction of the hydrogen bonds responsible for the formation of a colloidal microgel. Interestingly, at temperatures above VPTT, the microgels keep their integrity due to enhanced hydrophobic interactions between the polymer chains of the microgel and are no longer affected by pH changes. [ABSTRACT FROM AUTHOR]