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Wanted to go Organic: soapy water makes leafs brown HELP

Hello, I wanted to grow my 2 tomato plants organically. The only problem I had so far were aphids, CDC have recommended spraying leafs with soapy water. I used 7th generation liquid dish soap (is in it earth friendly). It worked on aphids, OK (I still found few stubborn ones) however the next day leafs got covered in tiny black spots and turned brown color in some places. Did I use too much soap? the areas to be most affected seemed to be on the back side of the leaf, where I sprayed the most. PLEASE HELP




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Mod Emeritus
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Welcome to the Helpful Gardener forum! :)

Pure soap, in the ratio of 1 tsp per quart of water, is usually okay. Detergents, however, will burn leaves. Did you use dishwashing liquid? Many of them are actually detergents, which have greater grease-cutting abilities than pure soap.

Read the label on the container of whatever it was that you used for "soap."

If you find that you used a detergent, just don't use any more of it on the plant. You might want to hose the plant off, as well, which might help prevent more damage.

I think the best treatment for aphids is just to wash them off the plant with a stream of water from the garden hose. :)

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Joined: Tue Jul 07, 2009 6:11 pm

Thank you so much, it was a detergent and I did go wild with it :oops: . Hosing off aphids seems to work but there is a lot of rain in my area and I am afraid to over water my tomatoes.
but now I have a really stupid question: where do you get plain soap? everything is with moisturisers, antibacterials, fregnances and who knows what else.

Super Green Thumb
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Location: El Cerrito, CA

Liquid Ivory is one liquid soap. It has no specific virtues other than I was able to remember its name just now! :lol:

You can also make your own "liquid soap" by saving those little bits at the end of bar soap (non-fragranced, etc., like a castile soap) and putting them in a jar. Add some warm water and swish it around until the bar end has dissolved.

Et voilá! Use 1 tsp. (or maybe 2 tsp. depending on your experience) per quart of water. Metric: 5 mL per Liter.

Cynthia H.
Sunset Zone 17, USDA Zone 9

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I like Dr. Bronner's liquid soaps -- I get them from Whole Foods and some from Trader Joes. WF has the full selection -- baby/unscented, peppermint, lavender, eucalyptus, citrus (used to be lemon but now it's orange, I think), almond, tea tree oil, rose. I regularly buy peppermint and tea tree oil so I tend to use one or the other, but when I have it, I've also used eucalyptus.

Green Thumb
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Joined: Sat May 31, 2008 3:37 pm

Get yourself a bar of soap, and grate it with a cheese grater. Add a handful to an empty dish detergent bottle and fill with warm water. Now you have liquid soap and it costs almost nothing!

The Helpful Gardener
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The Dr. Bronner Mint soap is famous as it chases bugs away too... :D


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