Aspirin Spray for Plants

The Plant Protection Process

• In 2003, scientists at Cornell University announced the discovery of a gene that responds to an increase in salicylic acid in plants. When levels of the chemical increase, the gene acts as a traffic controller by directing the compound to parts of the plant that need it the most. The gene also triggers cells infected by the disease to self-destruct, and it activates a plant-wide immune response against that disease. In 2009, scientists at Washington State University found another piece of the puzzle when they learned that calcium binds to the plant protein calmodulin when a plant is under attack. That binding process signals the plant to produce increased amounts of salicylic acid.

Aspirin Treatment Research

• Armed with the information that plants fend off attacks by producing salicylic acid, botanists experimented with a solution of aspirin and water, which they applied to plants stressed by disease. When master gardeners at the University of Rhode Island sprayed tomato plants with the solution, those plants produced more tomatoes than plants that were commercially fertilized. The tomatoes from aspirin-treated plants were, however, smaller. The stunting effect is a byproduct of the immune response, which diverts nutrients from the growth process to the battle against disease.

Commercial Treatments

• Because salicylic acid slows plant development, manufacturers have worked to create man-made chemicals with properties similar to salicylic acid but without its toxicity. Novartis developed a substance they called Actigard, which was effective in protecting some plants against a limited number of diseases. Stunted development remained an issue, however. Further research resolved the growth slowdown, and Actigard is now available under the Syngenta trademark. It is considered effective in controlling certain diseases in tomato plants, leafy vegetables and tobacco without slowing plant growth.

Homemade Aspirin Solution

• Some gardeners have had success with a homemade aspirin solution. To discover if aspirin can be effective in your garden, conduct an experiment. Plant four or more specimens of the same vegetable. Mix a test solution by dissolving 1 1/2 uncoated aspirin tablets in 2 gallons of water. Spray the foliage every two weeks. The other half of the plants will be your control group. Apply plain water to those plants on the same schedule. Keep track of the overall health of both groups and record the size and quantities of the yields. At the end of the season, you should have a good idea whether applying a solution of aspirin and water works for your gardens.