Utilization of polyanhydride nanoparticle encapsulated fungicide seed treatments against seedborne and soilborne Fusarium graminearum on maize
Fusarium graminearum is a soilborne and seedborne fungus that can cause significant losses on maize through a variety of different diseases, including seedling blight. Seedling blight is usually managed by utilizing fungicide seed treatments, but unfavorable germination environments and high levels of inoculum can still cause significant losses. Therefore, improved seed treatment efficacy is needed. Amphiphilic polyanhydride nanoparticles (PAN) have been used to enhance efficacy and provide sustained release of several active ingredients in animal systems and have potential for use in crop production.
To assess the potential benefits of PANs in seed treatment formulations, we performed two types of experiments with maize seeds. In the first experiment, seeds were inoculated with F. graminearum (seedborne inoculum) and then treated with PANs loaded with varying rates of fludioxonil (FLD) or thiabendazole (TBZ). In the second experiment, seeds were treated with uniform rates of PAN-encapsulated FLD or TBZ and exposed to unfavorable germination environments in the presence of soilborne inoculum. Controls included commercial rates of FLD and TBZ without PAN encapsulation, as well as untreated seeds and noninoculated treatments. Seedborne inoculum experiments with half rate of TBZ (0.025mg) loaded PANs protected root length similarly to full rate non-encapsulated TBZ, but PAN-encapsulated FLD did not perform as well as non-encapsulated FLD. In soilborne inoculum experiments, disease symptoms were severe and there were few differences among treatments. PAN-encapsulated TBZ performed similarly to non-encapsulated FLD and TBZ in shoot length when emergence was delayed from zero to three weeks. However, PAN-encapsulated fungicides did not increase or prolong efficacy over non-encapsulated formulations.
PAN-formulated seed treatments have the potential to provide tailored release systems for fungicides to protect against soilborne and seedborne diseases under a variety of different environments and potentially using a range of active ingredients. Our results indicate that PAN-encapsulation may facilitate use of reduced rates for some active ingredients, but more work is needed to demonstrate their potential to prolong efficacy under delayed emergence conditions.