Simon, who had been closely monitoring Maria’s fields, didn’t miss this sign. Simon, who had already developed great confidence in Maria’s farming methods, had sent people to gather pyrethrum after she found and made chrysanthemum water.

Seeing the results, they boiled large quantities of chrysanthemum water from the gathered pyrethrum and distributed it across the Duke’s private plots, where the serfs were responsible for spraying it.

Other serfs soon noticed how effective the slightly fragrant water was against pests in the fields. They approached the steward, cautiously expressing their hope to purchase some of this water from the Duke—if the price was reasonable.

This time, Simon kept the chrysanthemum water’s...