Help heirloom tomatoes resist disease by using aspirin in the soil or dissolved in water for a leaf spray. Be sure not to overdose the plant, though. (Todd McInturf / The Detroit News)
Heirloom tomatoes are all the rage with today’s gardeners because of their superior flavor, but sadly many lack the disease resistance needed to get through the summer. Southern Californian tomato maven Steve Goto (gotomato.us.com), who grows more than 900 varieties of heirloom tomatoes, recommends the use of aspirin to help keep his tomatoes disease free.
Researchers at the University of Florida and the USDA have confirmed that salicylic acid, the active ingredient in common aspirin, activates and boosts the natural SAR (Systemic Acquired Resistance) in plants against bacterial, fungal and viral diseases.
The original formula calls for dissolving 1½ (325 mg) uncoated aspirins in 2 gallons of water mixed with 2 tablespoons of a mild dish soap that acts a surfactant. The surfactant lowers the surface tension of the aspirin and water solution so it spreads evenly on the leaves of the plants and sticks to them rather than beading up. An anti-transpirant, such as Wilt-Pruf, is another option. Spraying the plants every three weeks will improve their resistance to disease and insects and also will increase their yields. Be sure to hit the undersides of the leaves, too.
For large plants such as tomatoes, Goto suggests inserting 2 aspirins 2 inches deep in the soil, one each on opposite sides of the plant. This treatment will last the entire season.
More is not better as far as the number of liquid applications or aspirins stuck in the soil. Too much salicylic acid may damage the plants. So if you stick the 2 aspirin in the soil, do not use the liquid spray on the tomatoes. And if you use the liquid spray, be accurate with your measurements and timing. Mark the spray dates on your calendar.
Along with my tomatoes, I plan to use the aspirin spray on cucumbers and squash plants. Beans, kale and Swiss chard are also on my list to spray. To prevent sun damage, use the spray at sundown or early in the morning.
This protocol also works on roses and other flowering plants. I’m going to see if this aspirin solution will extend the life of my cut flowers.
Appearances: Join me on the Grosse Pointe Garden Walk on June 21. From 2-4 p.m., I will be with perennial expert Susan Martin in the garden of Peter and Kelly Oliver to answer your garden questions. Garden walk tickets are $12 pretour and $15 on tour day. For information, call the Grosse Pointe War Memorial at (313) 881-7511.
Nancy Szerlag is a master gardener and Metro Detroit freelance writer. Her column appears Fridays in Homestyle. Email her at Szerlag @earthlink.net. You can also read her previous columns at detroitnews.com/homestyle.