Silver nanoparticles + wormwood extract = new phytophthera fungicide

Phytophthera is a genus of fungi-like oomycetes (water molds) which can affect about 400 species of plants, including many agricultural, horticultural, and natural areas species.  The diseases can affect many different parts of the plants, causing blights, crown rots, root rots, stem rots, etc. Estimations worldwide are in the multibillion dollar range for crop loss due to Phytophthera diseases.  Phytophthera species have also developed resistance to many existing fungicides, and so researchers have been experimenting to find a new treatment plan.

Phytophthora root and crown rots (Phytophthora spp.) by Don Ferrin, Louisiana State University Agricultural Center, Bugwood.org

Sliver nanoparticles are, like they sound, really, really small pieces of silver.  The average size of a silver nanoparticle is 5-100 nanometers, which, to give you the an idea of size:

10 nm is the lower size of tobacco smoke particles
20-80 nm is the thickness of cell walls in some bacteria
50 nm is the size of the largest airborne viruses

Phytophthora root and crown rots (Phytophthora spp.) sporangia by Bruce Watt, University of Maine, Bugwood.org

Those sporangia are about 50,000 nm long; the largest silver nanoparticles are 50 times smaller!

Silver nanoparticles on their own seem to display antibacterial, antifungal, and antitumor activities and have been evaluated for use in everything from textiles to wound dressings.  There are several hypotheses as to exactly how the silver nanoparticles, primarily about their interaction with elements within the cells inhibiting enzyme and protein functions.

In the last couple of years, researchers have also found that wormwood (Artemisia absinthium) has antioxidant activity.  By combining the silver nanoparticles with the wormwood extract, researchers have come up with a product that is effective against several strains of Phytophthera and, due to the multiple ways that silver nanoparticles affect cells, there is little concern for Phytophthera developing resistance.

wormwood (Artemisia absinthium) by Chris Evans, Illinois Wildlife Action Plan, Bugwood.org

To read about the research: Researchers Find a “Silver Bullet” to Kill a Fungus That Affects More Than 400 Plants and Trees
Phytophthera Images: Phytophthera spp.
Wormwood Images: Artemisia absinthium