Eco-friendly PEG-based controlled release nano-formulations of Mancozeb: Synthesis and bioefficacy evaluation against phytopathogenic fungi Alternaria solani and Sclerotium rolfsii

Degradable Poly(3-hydroxybutyrate)-The Basis of Slow-Release Fungicide Formulations for Suppressing Potato Pathogens

Three-component slow-release fungicide formulations with different modes of action of the active ingredients for suppressing potato pathogens were constructed for the first time. The difenoconazole, mefenoxam, prothioconazole, and azoxystrobin fungicides were embedded in the degradable polymer P(3HB)/birch wood flour blend and examined using SEM, IR spectroscopy, X-ray analysis, DTA, and DSC. Results showed that no chemical bonds were established between the components and that they were physical mixtures that had a lower degree of crystallinity compared to the initial P(3HB), which suggested different crystallization kinetics in the mixtures. The degradation behavior of the experimental formulations was investigated in laboratory micro-ecosystems with pre-characterized field soil. The slow-release fungicide formulations were prolonged-action forms with a half-life of at least 50–60 d, enabling gradual and sustained delivery of the active ingredients to plants. All slow-release fungicide formulations had a strong inhibitory effect on the most common and harmful potato pathogens (Phytophthorainfestans, Alternarialongipes, Rhizoctoniasolani, and Fusariumsolani).

Recent advances and remaining barriers to producing novel formulations of fungicides for safe and sustainable agriculture

BACKGROUND

Fungi have evolved for 1 billion years and due to their adaptability and resilience can be found in multiple habitats around the globe. Among numerous species of fungi, some are pathogenic, and humans have battled since the dawn of organized agriculture to reduce production losses. With the arrival of fungicides many gains have been made in this struggle. However, though fungicides have greatly contributed to substantial increase in agricultural productivity, their over usage has led to both health and environmental repercussions. They remain cornerstone of the agriculture industry, however, development of safer formulations to champion sustainable and eco-friendly agriculture is of great importance, especially in face of a growing global population, climate change and increasing fungal resistance to existing compounds.

SCOPE AND APPROACH

The aim of this review is to present the state of the art in fungicides formulations developed for agrochemistry, also describing recent improvements in their safety, with special focus on fungicides used most against the ten most important fungal pathogens.

KEY FINDINGS AND CONCLUSIONS

The major focus in the field remains to be the improvement of the overall performance of the fungicide formulations. The research trends are also moving towards developing more eco-friendly formulations. However, there are still very few studies assessing nanoformulations toxicity and environmental impact. For example, there is still a limited body of research on the holistic assessment of nanoformulation shells' fate in soil and in the environment after release, as well as redistribution within plants after absorption, with no studies on human or environmental exposure.

trans-2-Octenal, a single compound of a fungal origin, controls Sclerotium rolfsii, both in vitro and in soil

BACKGROUND

Sclerotium rolfsii is a soil-borne phytopathogenic fungus that causes diseases in economically important crops. Eradication of the fungus is hampered by its wide range of hosts, as well as its capacity to form sclerotia. Recently, we have shown that the endophytic fungus Daldinia cf. concentrica emits biologically active volatile organic compounds (VOCs); we also demonstrated that one VOC, trans-2-octenal, was the most effective against various phytopathogenic fungi. Thus, the aim of this study was to examine the potential of this compound to control hyphae and sclerotia of S. rolfsii, both in vitro and in soil.

RESULTS

We found that in vitro exposure of S. rolfsii mycelium to trans-2-octenal in air fully inhibits and kills the fungus. Elimination of sclerotia viability occurred at the same concentration, but direct contact between the sclerotia and the compound was needed. trans-2-Octenal also affected the viability of both hyphae and sclerotia of S. rolfsii in small pots containing loam soil.

CONCLUSION

We suggest the use of trans-2-octenal as a novel compound to control S. rolfsii. © 2020 Society of Chemical Industry.

Metabolomics reveals differential mechanisms of toxicity of hyperbranched poly(ethyleneimine)-derived nanoparticles to the soil-borne fungus Verticillium dahliae Kleb

There is a consensus on the urge for the discovery and assessment of alternative, improved sources of bioactivity that could be developed as plant protection products (PPPs), in order to combat issues that the agrochemical sector is facing. Based on the recent advances in nanotechnology, nanoparticles seem to have a great potential towards the development of the next generation nano-PPPs used as active ingredients (a.i.) per se or as nanocarriers in their formulation. Nonetheless, information on their mode(s)-of-action (MoA) and mechanisms of toxicity is yet largely unknown, representing a bottleneck in their further assessment and development. Therefore, we have undertaken the task to assess the fungitoxicity of hyperbranched poly(ethyleneimine) (HPEI), quaternized hyperbranched poly(ethyleneimine) (QPEI), and guanidinylated hyperbranched poly(ethyleneimine) (GPEI) nanoparticles to the soil-born plant pathogenic fungus Verticillium dahliae Kleb, and dissect their effects on its metabolism applying GC/EI/MS metabolomics. Results revealed that functionalization of HPEI nanoparticles with guanidinium end groups (GPEI) increases their toxicity to V. dahliae, while functionalization with quaternary ammonium end groups (QPEI) decreases it. The treatments with the nanoparticles affected the chemical homeostasis of the fungus, altering substantially its amino acid pool, energy production, and fatty acid content, causing additionally oxidative and osmotic stresses. To the best of our knowledge, this is the first report on the comparative toxicity of HPEI, QPEI, and GPEI to filamentous fungi applying metabolomics. The findings could be exploited in the study of the quantitative structure-activity relationship (QSAR) of HPEI-derived nanoparticles and their further development as nano-PPPs.

Amphiphilic polymer based nanoformulations of mancozeb for management of early blight in tomato

Controlled release (CR) nanoformulations of Mancozeb (Manganese-zinc double salt of N, N-bisdithiocarbamic acid), a protective fungicide, have been developed using poly (ethylene glycols) (PEGs) based functionalized amphiphilic copolymers and evaluated for the management of early blight in tomato. During the field experiment, it was observed that number of infected leaflets/plants were less in developed formulation treated plants as compared to commercial products. Number of infected leaflets per plant was 2.40-4.60 and the number of fruits per plant were 6.40-9.00 at 50 mg L^-1, whereas at 100 mg L^-1, the corresponding numbers were 2.10-4.10 and 6.30-9.10 respectively. These formulations can be used to optimize the release of Mancozeb to achieve disease control for the desired period depending upon the matrix of the polymer used. Importantly, sufficient amount of active ingredient remains available for a reasonable period of time after application leading to reduced number of applications of pesticide.

Nanoparticles as a Solution for Eliminating the Risk of Mycotoxins

Mycotoxins are toxic secondary metabolites produced by certain filamentous fungi. The occurrence of mycotoxins in food and feed causes negative health impacts on both humans and animals. Clay binders, yeast cell walls, or antioxidant additives are the most widely used products for mycotoxin elimination to reduce their impact. Although conventional methods are constantly improving, current research trends are looking for innovative solutions. Nanotechnology approaches seem to be a promising, effective, and low-cost way to minimize the health effects of mycotoxins. This review aims to shed light on the critical knowledge gap in mycotoxin elimination by nanotechnology. There are three main strategies: mold inhibition, mycotoxin adsorption, and reducing the toxic effect via nanoparticles. One of the most promising methods is the use of carbon-based nanomaterials. Graphene has been shown to have a huge surface and high binding capacity for mycotoxins. Attention has also been drawn to polymeric nanoparticles; they could substitute adsorbents or enclose any substance, which would improve the health status of the organism. In light of these findings, this review gives new insights into possible future research that might overcome challenges associated with nanotechnology utilization for mycotoxin elimination from agricultural products.