Functional, eco-friendly, and starch-based nanocarriers with sustained release of carvacrol for persistent control of tomato gray mold

Carvacrol (Car) is a promising botanical fungicide. However, the volatile and easily oxidizable characterization of Car hinders its practical application. Herein, an eco-friendly, starch-based nanopesticide (Car@ACS) was successfully constructed by encapsulating of Car within acetylated corn starch, enabling sustained release to prolong its efficacy. In vitro release experiments showed that the release of Car from commercial carvacrol soluble concentrate (Car SL) was 98.4% within 4 h, while that of Car@ACS released 36% within 4 h and 79% within 48 h, demonstrating the endowed sustained release property of the starch nanoparticles. Meanwhile, in vitro antimicrobial activity experiments revealed the fungicidal ability of the prepared Car@ACS and carvacrol technical (Car Tech) with the same concentration of active ingredient to be comparable Botrytis cinerea. In the 7-day pot experiment, the efficacy of the Car@ACS group (56.9%) against B. cinerea was significantly greater than that of the Car SL group (33.3%). In addition, the Car@ACS formulation improved the foliar retention of Car compared to Car SL in hydrophilic cucumber and hydrophobic peanut leaves. Finally, biosafety tests indicated that Car@ACS did not significantly affect the germination or growth of tomato seedlings. Therefore, the advantages of long-lasting disease control properties, improved foliar retention and eco-friendliness indicate that Car@ACS has significant potential to facilitate the application of volatile botanical fungicides.