Tomato Blossom End Rot – How to prevent it. A Frugal Garden tip that isnt included in the article is using Aspirin \u2013 Dissolve 3/4 of an uncoated asprin tablet in 1 gallon of water. Spray plants ever 2-3 weeks with the mixture to prevent fungus problems, including powdery mildew and black spot. It\u2019s also been found to help some plants yield more fruit than using commercial fertilizers.