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Beach Park, IL.

So I've read that spraying the leaves with seaweed will cut down on the chances of powdery mildew. Is this true??

7/20/2006 2:18:20 AM

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It might cut it down some but it won't stop Powdery Mildew in my experience.

I tried relying on Neptune's Fish/Seaweed one year at my son's elementary school. The goal was to spray every 7 days. We did not get the Powdery Mildew suppression that was desired. This might be because I missed a couple sprays to rain or a hectic work schedule which stretched the interval to 10-11 days.

I never did find any published data to suggest that seaweed extracts control PM. I did find other non-chemical treatments.

If you're in need of a "natural" fungicide for PM, then consider a 10% Milk spray every 7 days. This treatment has been used & the published efficacy data looks pretty convincing. This is what I'm using at the school this year but it's too earlty to comment on the results yet.

http://www.backyardgardener.com/tv/mildew.html

Another "soft" treatment is a spray of 1% Stylet Oil (1.3 oz of oil per gallon) with 1.2 oz of Armicarb 100 (potassium bicarbonate) or even plain baking soda.. Only use the Stylet Oil if the temperatures are low (less than 85°F). Higher temps call for straight Armicarb 100.

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7493.html

All of these possible solutions must be applied to the leaf bottoms which is where Powdery Mildew gets it's start.

http://www.stylet-oil.com/

http://www.greenbook.net/docs/Label/L51420.PDF

7/20/2006 7:35:02 AM

Western NY

i think it helps a little, but fish would be the better option if you're looking to buy something. and i'd be spraying more than twice a week to be effective.

7/20/2006 8:19:12 AM

Colorado

I grew a plant at work last year in a raised concrete planter, next to twelve foot
high plate glass windows and an asphalt parking lot. Crap soil. Started to develop
PM in early November. Sprayed the bottoms and tops of the leaves with only
Neptunes fish and seaweed. PM disappeared within two days. Plant continued
to grow until November 14th when it was killed by a hard frost. Amazing
plant considering the bad soil and extreme heat. It should not have survived past
the 4th of July. The fish and seaweed is great stuff. ------LB

7/20/2006 11:06:22 AM