Thank you for your question.

As volunteer Master Gardeners of the University of Minnesota, we strive to base our suggestions on scientific information derived from peer reviewed articles and publications. Inherent in these publications would be the results of experimental studies in which tomatoes would have been exposed to both the presence and absence of aspirin, keeping all other growing conditions the same. Comparison of the final results might then have some significance. In looking over most of the articles that assert that aspirin is effective against tomato blight, we find that none of these types of experiments were done. What is true is that in 2014 workers at the United States Department of Agriculture found that pure salicylic acid appeared to confer upon tomatoes some resistance against certain infectious agents. For whatever reason, that paper has been archived and removed from public distribution. Aspirin does contain salicylic acid along with numerous other compounds. If tomatoes are treated with an aspirin spray, it is impossible to determine if the final results are due to the salicylic acid and/or other compounds present. In short, the evidence appears to be very thin as to whether or not tomatoes benefit from an aspirin spray. U-tube videos and newspaper articles should not really form a sound basis for our gardening endeavors.

See:

https://www.gardenmyths.com/aspirin-spray-tomatoes-vegetable-garden/

https://blogs.ifas.ufl.edu/orangeco/2019/12/31/garden-home-remedies-fact-or-fiction/

Again, thanks for the interesting question.