Pesticides

Illustration of a spray insecticide instrument, with accompanying textSuccessful mass cultivation of plant species is dependent on the ability to tackle common sources of plant disease, whether by the development of disease-resistant strains, the use of protective barriers to shield plants from pests or the application of fungicides and insecticides.

By the late 19th century, as this publication shows, government-led research programmes had already led to the availability of cheap and effective chemical fungicides and insecticides.

The pages shown here, taken from a rare surviving copy of the bulletin of the Grenada Botanic Garden, reproduce text and illustrations from a United States Department of Agriculture circular, detailing a spray insecticide. As the text makes clear, the insecticide, which could be distributed from a knapsack pump worn on an agricultural worker’s back, was principally used in the USA for spraying apple trees.

The staff of the Grenada Botanic Garden were interested in its potential use in cocoa plantations and in orchards of citrus fruits, both of which were present on the island.

Kerosene (paraffin) and condensed milk formed the principal ingredients of most insecticides then in use. Kerosene, a flammable hydrocarbon produced from a distillation of bituminous coal and shale oil, was patented in 1854 by the Canadian geologist Abraham Gesner and is an effective insecticide, applied both in agriculture and in personal care, providing a common treatment for head lice.

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