Lignin nanoparticles containing essential oils for controlling Phytophthora cactorum diseases

Phytophthora cactorum is a plant pathogen affecting a wide range of hosts, causing economically damaging diseases, such as damping off and root rot, in fields and nurs- eries. Current plant protection strategies are often inadequate to control Phytophthora diseases. Hence, an attempt was made to evaluate the potential of a novel control method using lignin nanoparticles loaded with essential oil of Thymus serpyllum (EO- LNPs) for controlling P. cactorum infections on Pinus nigra in vitro and greenhouse con- ditions. Nanoparticles were characterized by Py-GCMS and the drug efficiency, and drug loading capacity were determined using HPLC. T. serpyllum essential oils (EOs) were characterized by gas chromatography (GC-FID and GC-MS). Under in vitro con- ditions, the median effective concentration (EC50) values were 20.453 and 88.711 μg/ ml, for EOs and EO-LNPs, respectively. Furthermore, in vivo tests revealed that thyme EOs and EO-LNPs were very effective in reducing the mortality of inoculated pine seedlings, with an inhibition rate of 93% and 100%, respectively. Results reported in this study open the possibility of using EO-LNPs for improving plant health in green- house settings. The design of new protection strategies relying on lignin nanoparticles conforms to the principles of the circular economy.