I was chatting to some allotment holders yesterday and, worried about the prospect of late blight on their potatoes and tomatoes they were talking about treating the plants with an aspirin.
I honest though I had misheard, and yet there is some very sound research that points to aspirin being a new, and rather unusual ally to vegetable gardeners.
James Wong, of Kew Gardens fame, has been discussing this very matter and explains that the aspirin triggers the plant to develop what is called “systemically acquired resistance” a state where the plant is prepared for a pest or disease attack and is therefore more able to overcome it.
The Independent Newspaper reported (11th May 2014) that “Scientists at the US Department of Agriculture (USDA) found that salicylic acid – the active ingredient in aspirin – primes plants in the nightshade family, including potatoes and tomatoes, against microbial or insect attack, according to a study published in the Annals of Applied Biology.
Rebecca Brown, a professor of plant sciences at the University of Rhode Island, who has conducted trials on tomatoes, recommended adding 250 to 500mg of aspirin to around 4.5 litres of water and spraying this on plants two or three times a month.
However, Professor Brown told Fine Gardening magazine that this solution was only effective “before the first sign of disease”.
For organic gardeners, she suggested using willow water made from fresh-cut trees. “Willows are naturally high in salicylic acid,” she said.
This concept of “systemically acquired resistance” is becoming more important as we develop a new concept in crop protection chemicals.
Some plants are use this concept of “systemically acquired resistance” naturally, for example when a plant under pest attack releases hormones which “warn” other plants in the area of an attack. These plants respond, for example by increasing the tannin concentration in their sap, thus producing what is known as an antifeedant effect.
I strongly suggest that this is not the last time we will be reading about “systemically acquired resistance.”