Saturday, July 19, 2014

Downy Mildew on Sweet Basil!

Leaf of "Organic" Sweet Basil with Downy Mildew
Underside of Same Leaf with Downy Mildew
A Whole Mess of Sweet Basil Seedlings with Downy Mildew! :(
I Really Don't Know Why This Basil is Doing OK!
The Experiment of Keeping the Sweet Basil Inside Has Not Helped the Downy Mildew!
I'm Encouraging The Herbal Husband to Get Rid of It!

Well, I can finally take a break from picking raspberries and making jam.  Never had this many great raspberries this early!  I did want to address this topic because it could be devastating to your sweet basil plants.  It is called downy mildew.  It exists in some vegetables, perennials and in the cruelest choice possible for herb lovers to sweet basil.  The good news is that at the moment the disease does not seem to affect other basils varieties, lemon, Thai, cinnamon, etc.  As Dr. McGrath calls them the fruit and spice varieties.  The other good news is that you can eat the diseased leaves and not die!   The Herbal Husband and I are living proof of that.  Also, in an ironic twist, the sweet basil that The Herbal Husband saved last fall from being dried by another local garden center was planted in the herb garden just recently and is doing fine at the moment.  Leaf moisture and humidity and limited air circulation are catalysts for downy mildew and we are having all of those at the moment!  So I will let you know if this basil gets the disease!  Fingers crossed!  The one big symptom of this disease is yellowing of the leaves which is a sign of a nutrient deficiency.  You can put a leaf that is showing symptoms but no spores in a plastic bag with a wet paper towel in the dark overnight to see if the spores will appear.  Good air circulation and sunlight will help keep your basil plants healthy.

The Herbal Husband has moved the seedlings in the container from outside to an inside western windowsill.  So as an experiment, he is still harvesting the leaves and the seedlings still have the disease.  A postscript to this story.  The downy mildew on the basil hasn't gotten better inside.  I keep gently nudging The Herbal Husband to get rid of it.  Surprisingly, the sweet basil from last fall that was inside until recently has done well outside now that the downy mildew is inside!

This is one of those diseases that you have to start spraying from the start.  Click on the link above for solutions and to participate in Dr. McGrath's study at Cornell University.  One solution for organic gardeners would be Neem oil.  Unfortunately we thought we were buying organically grown at a local garden center.  I think we will have to wait for a resistant strain of sweet basil and they are working on that.  The use of light in greenhouse situations for commercial growers has been found to be effective in limiting growth of the disease.  In any case you need to destroy your plants and preferably on a sunny day so that "the disturbed spores are killed by UV radiation."

It has really been rainy here!  We had almost 3 inches last week and an inch overnight!  I wish we could share it with the western states that need it so badly.  Hopefully you are having a great weekend.  Our thoughts and prayers go out to all those who lost their lives recently.  I will try to be more present and showing you what has been going on in the herb garden!  Talk to you later.


PeggyR said...

We are getting rain today, but at least the heavy downpours have stopped. Yes I wish we could send it out west!

lemonverbenalady said...

Thanks for stopping by Peggy! xo

Barbara said...

Oh no ! not a basil mildew!! I'll be devastated if my basil doesn't do well this year. I missed my basil harvest last summer due to illness and other issues at harvest time. I have some yellowing on the bottom leaves of a few plants. I am heading out there right now to check on my basil babies!!

lemonverbenalady said...

Yes, can you believe it, Barbara? I hope your basil babies are OK! xo