Sad Basil

Angela5237 · Mon Jul 14, 2014 11:30 am

Hey everybody!

So out of nowhere my basil is turning brown and is looking very sickly. Here on Long Island, I have a few neighbors whose basil is doing the same thing. Within two days there is a dramatic difference in the way that they look. I attached some photos of what the once green, delicious, vibrant plants looked like. Does anyone know what's going on? Can it be the heat and humidity that we've had constantly these past few weeks?

rainbowgardener · Mon Jul 14, 2014 11:38 am

No, basil should thrive on heat and humidity unless overwatered. Have you also been getting a whole bunch of rain?

Unfortunately it might be some disease. Are there dark spots on the undersides of the leaves:

https://1.bp.blogspot.com/_W_anctqLk3A/T ... ation3.jpg

That would be downy mildew, a relatively new disease that basil growers especially in the Northeast are having a lot of trouble with.

Angela5237 · Mon Jul 14, 2014 11:45 am

Yes there is, I just checked

What can I do now?

rainbowgardener · Mon Jul 14, 2014 4:29 pm

Yes, I'm afraid you may be right. Yellowing and wilting of the leaves is the first symptom of it. Unfortunately it is really really bad news.

There's not really a cure for it. Usually what they say is bag up the plant to keep the spores from escaping and trash it.

Then don't use the soil they are in for basil ever again (if it is only a small amount of potting soil, you might just want to trash the soil also). The spores can remain in the soil for up to 8 years.

You can start over with new plants and new soil (having bleached the pots first). Green/ sweet basil is the most susceptible. Now that you know you have the the disease around, you would be better off to grow red or purple basil, lemon basil, lime basil, cinnamon basil, etc. Make sure there is plenty of air circulation around them. Don't water the leaves, only the soil. And use fungicides preventatively. The fungicides don't really cure the disease, but they can help prevent it. That would include baking soda solution or hydrogen peroxide.

Here's an article about it: https://vegetablemdonline.ppath.cornell. ... Downy.html

ElizabethB · Mon Jul 14, 2014 5:23 pm

DITTO RBG. Another thing I noticed is that you plants are crowded. One - no more than 2 per bucket. Over crowding encourages downy mildew. What about drainage? Basil likes well drained soil.

I agree that you need to start over.

So sorry.

imafan26 · Mon Jul 14, 2014 8:13 pm

You can report the basil downy mildew on the Cornell site.
I could not plant basil for two years after getting downy mildew. The spores hang out in the air as well.

I was told to try planting in summer when it is drier, plant farther apart to improve air circulation, and to check sage which may also be a carrier of the disease.

Most fungicides don't work. I have tried neem and sulfur and it did not help. I am going to try milk and hydrogen peroxide next. If I can find a fungicide that works, I am hoping to get the basil to live long enough for it to breed with a more resistant basil.
https://vegetablemdonline.ppath.cornell. ... Downy.html
https://www.extension.umn.edu/garden/yar ... ny-mildew/

mattie g · Tue Jul 15, 2014 9:20 am

I didn't need to go past your first picture before I identified that as downy mildew.

I'll piggy-back on what others have said. Unfortunately, your basil is done. I'm really sorry about that. There's nothing you can do about it, and there's no known treatment for it, nor is there a good way to keep from getting it if the spores are around. You can probably hold it off for a bit, but it'll eventually get at your basil. I'm just waiting for the first fuzz to show on mine this year, because I know it'll happen sooner or later.

It's a devious disease, and I hope some smart people come up with a treatment for it soon...

Angela5237 · Tue Jul 15, 2014 10:37 am

Thank you so much to everyone who participated in diagnosing my poor basil and for the great words of advice! It was so sad pulling the plants out of the pots and throwing them out. I bought new baby plants yesterday and they are planted in different pots and near my tomatoes in the garden. Now we hope for the best!

I hope you all can steer clear of this disease.

Thank you all again!

rainbowgardener · Tue Jul 15, 2014 11:03 am

True that there is no treatment so far, but as noted there are preventatives, including growing more resistant varieties than the sweet basil. I love purple basil and it is not very susceptible to the downy mildew. And you can start from the beginning treating with fungicide such as baking soda solution, diluted milk, or hydrogen peroxide. Treat every week or two or after it rains. That should help keep your new plants from coming down with it. But I would start right away, since you know the spores are around.

imafan26 · Tue Jul 15, 2014 11:46 am

There are efforts being made to develop a more resistant strain of sweet basil. It is not so much not being able to find a cross, but to make the basil resistant without changing the flavor.

Other basil that are resistant are cinnamon, lemon, lime, and African basil. African basil has been crossed with purple basil to produce the African blue basil. I have been able to cross cinnamon and Thai basil to get a more resistant Thai basil. It is not 100% resistant, but it survives to be harvestable. I was told to keep the most resistant basil and keep crossing them.

JC's Garden · Tue Jul 15, 2014 11:52 am

Downy mildew is something I've not encountered. I'm sure I'll see it one day. Right now I'm growing Sweet, Italian and Thai. Question. How resistant is the Italian?

mattie g · Tue Jul 15, 2014 1:31 pm

JC's Garden wrote:Downy mildew is something I've not encountered. I'm sure I'll see it one day. Right now I'm growing Sweet, Italian and Thai. Question. How resistant is the Italian?

Since you make a distinction bewteen Sweet and Italian Basils, my guess is that your "Italian" is actually Genovese Basil*. If that's the case, then its susceptibility is similar to that of Sweet Basil.

* Italian Basil isn't a separate cultivar. It's a term used to refer to the basils generally used in Italian cooking - either Sweet or Genovese.

JC's Garden · Tue Jul 15, 2014 2:00 pm

mattie g wrote:
Since you make a distinction bewteen Sweet and Italian Basils, my guess is that your "Italian" is actually Genovese Basil*. If that's the case, then its susceptibility is similar to that of Sweet Basil.

* Italian Basil isn't a separate cultivar. It's a term used to refer to the basils generally used in Italian cooking - either Sweet or Genovese.

I did not know Italian also included Sweet. You are right, it is Genovese that I have been calling Italian. I appreciate you taking the time to answer. I learned something.

mattie g · Wed Jul 16, 2014 7:40 am

JC's Garden wrote:I did not know Italian also included Sweet. You are right, it is Genovese that I have been calling Italian. I appreciate you taking the time to answer. I learned something.

Not a problem at all. Good luck!

Msek59 · Mon Aug 24, 2015 1:49 pm

I just joined this forum. I have suffered through the issues described herein, and have wondered what strains or names of basil are more hardy. I've heard of purple basil, red basil, and the like, but all I can ever find for sale near me in Austin, Texas is sweet basil. Where can I order clean basil plants? Should I order Thai, red, etc?

imafan26 · Mon Aug 24, 2015 2:08 pm

Holy basil and African blue basil are resistant. Lemon, lime, and cinnamon basil are moderately resistant but will get the disease when spore counts are very high and the basil are under stress.
Sweet basil and Thai basil are the most susceptible with thai basil hanging in there a little longer than sweet basil
The sweet basil cultivar Eleonora is supposed to have some resistance although like thai basil not complete. It tastes different and it is sold by Johhny seeds. They are out of stock.

I could not plant basil for 2 years because the spores are in the air. Getting rid of the plants are not enough, you have to wait long enough for the spore counts to drop. I had to spray the basil preventively weekly and I used neem and alternated with hydrogen peroxide. This year I am having luck with my last batch of basil. But, if Walmart which is less than a mile away from me starts selling sick basil, mine will be infected within a couple of weeks.

I try to plant basil in summer when their isn't going to be much rain and usually less humidity. Didn't happen this year with El Nino, it has been a wet and very humid August. I plant my basils in full sun with lots of air space around them and in a place where the air will not be blocked by other plants.