Powdery Mildew - my organic experience

veronica_p8(6/7 Pittsburgh)August 15, 2010

Ok, I know this disease has been talked about a lot, but I just wanted to quickly share my experience in my first year garden. I've found a lot of talked-about cures or treatments (I'm trying to be organic) so I've tried a few different ones over the past couple of weeks.

1. I've been using neem oil once or twice a week on almost everything in my garden ... I'm not sure if it was slowing the spread of PM down, but it definitely still continued to grow. This problem for me is mostly on my monsterous pumpkin vines, and in the 4x4 cucurbit sq ft garden bed.

2. When the neem wasn't doing what I wanted regarding the PM, I tried the milk treatment. I saw no relief and the PM advanced. I tried two different concentrations over a couple of days ... probaby 20 % and then 40%. I'm sure it works for some people ... it didn't work for me :(

3. So, I kept researching ... I read that cornmeal water was an effective fungicide. I decided to give it a try. No luck. My pumpkin and squash leaves just kept looking worse and worse, and the white spots kept getting bigger and in more placeson the leaves. I was definitely bummed out.

4. So TODAY ... I decided to try the baking soda in water spray. Omg. It was like magic. I can't wait to get up tomorrow morning and have a look. You know how tilex kinda kills all the ugly fungus in bathroom water areas (shower, around faucets, etc) ... (that is, if you don't scrub religiously and it actually NEEDS tilex ... let's just say I'm a big tilex fan :) )...

So, I sprayed pretty heavily ... I think my concentration was a little high (so I hope I don't find a pile of dead pumpkin leaves all over my backyard tomorrow). I used about 1/2 - 1 teaspoon per spray bottle of water. Back to my tilex analogy, I swear I could see the mildew disappearing just after I sprayed. It wasn't just because the leaves were getting wet. Some leaves that were hard hit by PM still looked yellowed with some brown spots where the white mildew had been heavily concentrated, but ... the white disappeared! That did not happen with any of my previous attempted treatments.

If this is a false alarm, and it's all back within the next couple of days, I'll post my depressing news, but right now, I'm THRILLED!


Happy pumpkining.


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Baking soda is an good fungicide and so is garlic water.

Whirl 5 or 6 cloves of garlic with a little water in a blender until they are basically mush--or--put them through a garlic press Put it in a jar and add a pint--2 cups of water and let it sit for 24 to 36 hours. Strain into a spray bottle and spray away. Your yard will smell like a pizzeria for a day or so but it works. Both these things work best when used at the first sign of mildew

    Bookmark   August 16, 2010 at 12:02AM
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Using Baking Soda to control various fungal plant diseases has been talked about since at least 1933.
Most often I find if someone has a problem with milk controlling Powdery Mildew it is because they used the wrong milk (I've had good success with fat free milk) or too weak a mixture (I've had best success with a 50/50 mixture of milk and water).
Garlic is a well known fungicide, but I've not seen much about using garlic in the garden for that.

Here is a link that might be useful: Baking Soda

    Bookmark   August 16, 2010 at 7:27AM
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rhizo_1 (North AL) zone 7

Veronica, thanks for the comprehensive report about some of the things you've tried for PM. Keep us posted about the baking soda results in future days.

Are you tending to the 'housekeeping' aspects of PM control, as well?

    Bookmark   August 16, 2010 at 1:36PM
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veronica_p8(6/7 Pittsburgh)

rhizo: Housekeeping, as in, removing diseased dying leaves? I have been for pumpkins, not so much for my cucurbits because they are very dense. I remove what I can, but there are some dead leaves pretty buried within the vines. I am not sure the cause of the dead leaves (is there a natural amount of leaves that die on a vine from "natural" (i.e., non disease/pest) causes?

I'm going to post another problem today with photos. Some of my butternut squash leaves are VERY chlorotic, and some dying, and I can't tell the cause, as others are healthy and green. (I don't think it's PM, but who knows?) I look forward to your expertise(s).

rhizo ... if there's something else I'm missing as far as "housekeeping" is concerned, please let me know! :) Thanks for taking the time to be concerned and answer.


    Bookmark   August 16, 2010 at 2:23PM
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