Gardening: Homemade concoction could protect tomatoes

Nancy Szerlag
Special to The Detroit News

If you’re a tomato lover, there’s nothing sadder than watching your homegrown tomato plants wither and die from the bottom up before you even get a chance to harvest a luscious red orb.

This year, I’m growing tomatoes in a community garden where tomato diseases run rampant. Issues include over-crowding as well as over- and under-watering and growing heirlooms that are not disease resistant.

Those issues won’t go away, but here’s a homemade potion that may make it possible to make a fabulous BLT with a homegrown tomato. This baking soda recipe is said to have been developed by Cornell University – not true.

It was tested at Cornell University but never endorsed. However, folks have been using it for years and swear by it because the homemade baking soda recipe is a cheap spray that often works for disease prevention and early control of many tomato diseases and can also be used on other edibles and roses. Just mix together 1 tablespoon baking soda, 1 tablespoon oil and a drop or two of dishwashing liquid in a gallon of water and spray away.

I use blue Dawn – if it’s good enough for washing oil soaked ducklings, it works for me.

The best oil to use is horticultural grade dormant oil or lightweight summer oil but many folks use vegetable oil, including canola and safflower. I only have a few tomato plants so I cut the recipe in half. As with all recipes, measure carefully.

To prevent leaf burn and harming beneficial insects, use this and all insecticides and pesticides (even those OMRI listed), in the very early morning or at sundown when the good guys are in bed.

Begin treating tomatoes and other vulnerable plants before any signs of disease appear. And spray the undersides of the leaves and the surface of the soil or mulch. Reapply weekly or after a rain.

If your tomatoes already display signs of disease, carefully cut off any leaves that show yellowing or brown spots and put them in the trash. These diseases are soil-borne, so mulching around the tomato plants will prevent more disease spores from splashing on to the leaves.

If this homemade brew is not working, take the next step and use one of the newer biological fungicides, such as Serenade or Natria Disease Control, that contain bacillus subtilis. Both products are OMRI listed and are safe to use on edibles when applied as directed: https://www.bayeradvanced. com/serenadegarden.

Nancy Szerlag is a master gardener and Metro Detroit freelance writer. Her column appears Fridays in Homestyle. To ask her a question go to and click on Ask Nancy. You can also read her previous columns at