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Assistant Cook
Oct 1, 2004
Hey Everyone,

My oregano (organically grown) plants are showing white spots on the leaves...I have never had this happen before. Any ideas on why this is happening? Is this a fungus? Are the leaves still safe to consume? This is a new one to me...I have been growing and using my own organically grown herbs for years and have never had this occur before. We have had a very cold, and very wet year this year in my area and and wondering if this is the culprit. Thanks in advance for any advise!
I hope someone can help you!!!! I don't know anything about this. I used to grow a BUNCH of herbs but never had any kind of fungus on them. Sounds like it may be due to your wet weather.

If you call your local agricultural department they will probably be able to give you a natural rememdy. One time on my chives (we moved to a house with not much sunlight so everything stayed kind of wet under the trees) of water, dish soap, and garlic. I made this concoction and then sprayed it on the plants.
tootstl, if it is a fungus, or more likely powdery mildew, the safest way to get rid of it is to buy powdered sulfur and sprinkle it on the plants. this is the best organic way to control fungus and mildew in the garden, but you'll need to repeat the treatment each time it rains cause the sulfur harmlessly washes off. i have problems with powdery mildew cause i compost a lot of apples from my tree, which promotes the mildew. i should turn my compost over a few times a year and lime it, but i'm lazy.
Tootstl, I believe Buckytom hit the culprit.

Tell me: Are these spots you describe small in size (1/4" and less) and primarily located on lower or interior older leaves? If so, grab a magnifier and look for a fuzzy, cottony growth within these spots. Next step, if you rub the spots, does the white fuzz rub off and is the leaf surface beneath them darkened and mottled? Are the leaves with lots of spots turning yellow? If this is the case, you have a 95% likelihood of having powdery mildew, which is a fungal disease.

If this is not the case, please advise, because it changes everything!

My best advice, based upon my own plant survival tactics this year, is to judiciously clean the area beneath the plant -- remove all old plant material -- and remove as many infected leaves as you can. Routinely spray with Neem Oil or your fungicide of choice. (As mentioned above, I have been, but I still have problems...)

As far as cooking with this oregano is concerned, wash, wash, wash the stuff. As long as you bring the oregano to a boil in a sauce, for example, and retain the boil for a few moments, you wil kill any and all fungus that remains on the leaves, and you will kill any thing else, for that matter. I would suggest that you not use any but the best leaves (unaffected) for uncooked dishes and, even if they are perfect in form, I cannot stress enough the rinsing process!

But you're an organic gardener. You know that!
Still in a quandry with my Oregano

Thanks Buckytom and Audio for your responses! But, alas, I know for sure that powdery mildew is not the culprit. The white spots are inherent in the leaves, such as a variegated variety would be, but I have never heard of a variegated oregano and these are two year old plants...I can't figure out where the spots came from! I have found no pests, no mildew, I have kept my beds immaculate and am just plain stumped on this one! Thanks much for your help, it is truly appreciated. By the by, this oregano has supreme flavor and I have dried a sufficient supply to take me thru the winter, including the most intense dried purple blossoms I have been able to dry to date! I just need to get my @## in gear and get my Romas processed ;)

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