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Location: Ferndale, WA

Black spots on sunflowers, neem oil NOT helping.

Anybody have any ideas or experience this before? I believe this is a velvet queen sunflower (if it's not, it's an appolos ring, or talk border mix of some type),these are all I started.

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Joined: Wed May 21, 2014 9:26 pm
Location: Upstate, SC

Re: Black spots on sunflowers, neem oil NOT helping.

Sounds fungal. I can't really see much from your photos, but they are generally prone to fungal infections. Baking soda and milk, neem oil, peroxide, copper fungicides. Any of those will help with prevention, but once the damage is done, the plant won't heal. The spots will persist. I'd remove what you can of the worst of the spotted leaves, and then do regular (you have to be consistent) treatments weekly to prevent.

I am getting good results with 1/4 cup neem oil extract and 1 heaping tablespoon of baking soda in 2 gallons of water weekly.
Upstate, SC
USDA Zone 7b/ Sunset Zone 31

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Joined: Tue Jan 01, 2013 8:32 am
Location: hawaii, zone 12a 587 ft elev.

Re: Black spots on sunflowers, neem oil NOT helping.

Most fungicdes work better is you start them before the problem shows up. Fungicides should be preventively used whenever wet humid weather prevails.
Make sure the plants are not planted too close together and they get plenty of air circulation in full sun.

Taking off the leaves are a good idea as it will also open up the plant more.
Happy gardening in Hawaii. Gardens are where people grow.

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