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Joined: Fri Jul 02, 2010 8:53 pm
Location: fresno, california

Will fish oil/baking soda harm praying mantis or lace wings?

Hi There!

New to forum so forgive me if this is addressed elsewhere. I read extensive postings and searched internet generally to no avail.

I've always landscaped with native, problem resistant plantings, and never used chemicals. However, I just moved into a new home and have powdery mildew / a few aphids on multiple rose bushes. Know I should probably just pull up bushes and plant something more resilient, but I hate to take the shovel to anything if there's an alternative.

Plentiful praying mantis / lace wings are keeping aphids controlled, but I still need to cure PD. I've picked off the worst damage, and was planning to spray product called Organicide (fish oil and lecithin) mixed with baking soda. Not confident about efficacy of this "fungicide", so I hate to risk killing beneficial mantis and lace wings. Anyone know if oil or baking soda is harmful to these little creatures?

Thanks so much for any feedback, Shana

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Super Green Thumb
Posts: 25279
Joined: Sun Feb 15, 2009 6:04 pm
Location: TN/GA 7b

any oil tends to be harmful to insects, that is the principle of Neem oil. You can control aphids also just by spraying salad oil on them. Clogs up their spiracles. But the same is true for the beneficials you want to save.

You could try a baking soda solution without the oil for your powdery mildew. Or a milk solution. Neither should be harmful to your beneficials.

Milk solution:
Dilute milk 50:50 with water. Add a tablespoon of yoghurt with active cultures and let it sit at room temperature for a few hours to culture the lactobaccillus. The lactobacillus is a fungicide that destroys the blight/ wilt /mildew fungi. Strain and spray on the affected plants, being sure to get the underside of leaves, leaf axils, etc.

If you have nearby unaffected plants, particularly of the same variety), I would dilute the solution down more and spray it on them preventatively.

Baking soda solution:
1 tablespoon of baking soda
½ teaspoon of liquid soap
1 gallon of water

Newly Registered
Posts: 2
Joined: Fri Jul 02, 2010 8:53 pm
Location: fresno, california

I tried oil, baking soda and castille soap before I got your advice. I found a report posted by an entomologist claiming beneficial insects that fly, or have longer legs (like mantis) will leave while you're spraying and come back later. Report also stated that once they return, mantis have long enough legs that they "walk over" oils with no ill effects.

However, I think you're right because, though I don't see mold now, I also haven't seen a mantis since I sprayed. Sad. I'll just use baking soda and soap next time.

Thanks so much for your response.

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