This molecule is a derivative of the antibiotic geldanamycin, which itself comes from the soil bacterium streptomyces.

FORBES: Magazine Article

The Streptomyces data are published in the scientific journal Nature.

BBC: Nature's medicine maker decoded

Specifically they discovered that Pythium ultimum, a fungus that attacks aubergines, peppers, lettuces, tomatoes and cucumbers as seedlings, Clavibacter michiganensis, a bacterium that kills young plants and deforms fruits, and Streptomyces scabies, a second bacterium, which causes potatoes to develop revolting scabs and for which no treatment currently exists, all stopped growing in the presence of the oil.

ECONOMIST: Tobacco extracts protect plants from pests and pathogens