Farmers searched for pesticides that could stop the San Jose scale. In the nineteenth century, they had a fearsome arsenal of poisons for killing weeds and insects. In the ancient empire of Sumer 4500 years ago, farmers put sulfur on their crops. The Romans used pitch and grease. Europeans learned to extract chemicals from plants. In 1807, chemists isolated pyrethrum from an Armenian daisy. To stop the San Jose scale, they tried whale oil. They tried kerosene and water. One of the best treatments they found was a mix of lime and sulfur. After a few weeks of spraying, the San Jose scale would disappear.

By 1900, however, the lime-sulfur cure was failing. Here and there, the San Jose scale returned