User avatar
MoonShadows
Senior Member
Posts: 150
Joined: Mon Dec 11, 2017 9:50 am
Location: Stroudsburg, PA - Zone 6a

Black Spots on Spinach Leaves

On Sunday afternoon while picking some spinach for salad, I found some small, what looked like, black bugs on the underside of some of the spinach leaves in my greenhouse. They seemed to be localized to one or two plants. I pulled the plants and disposed of them outside the greenhouse. Yesterday, I only found 1 leaf with a couple of those black "bugs". I picked it, and after looking at it through my 30x magnifying lens decided it is not a bug at all. I took a pin and easily opened it up. It was soft and black throughout. Not sure what it is. Any guesses?

Here's pic I found on the internet of it on a basil leaf.
KQar5Vf.jpg
Here's another one (ignore the powdery mildew in this picture)
12508153_f520.jpg
https://MoonShadowsFarm.com Good Eats & Treats from the Pocono Mountains
"Go confidently in the direction of your dreams. Live the life you have imagined." ~Henry David Thoreau

User avatar
applestar
Mod
Posts: 27805
Joined: Thu May 01, 2008 11:21 pm
Location: Zone 6, NJ (3/M)4/E ~ 10/M

Re: Black Spots on Spinach Leaves

From your description, I thought those must be the sporebearing body (mushroom) of the fungus that is already affecting the leaf.

I found a reference to it in this googlebook which I can’t access to copy the text, so I took a screenshot (attached below). I think the highlighted reference is regarding Pea mildew. There IS “spinach anthracnose” mentioned in the out of frame list, but I don’t think that is related.

Annual Report of the Ohio State Horticultural Society for the Year ... - Ohio State Horticultural Society - Google Books
https://books.google.com/books/about/An ... NQAQAAMAAJ
EA8D007E-5D97-4041-8D4A-D63028A17F6C.jpeg

... here’s a more modern reference ...

Identification of Powdery Mildew Fungi
https://www.apsnet.org/edcenter/intropp ... ildew.aspx
At the end of the growing season, powdery mildew fungi produce sexual spores, known as ascospores, in a sac-like ascus (pl. asci) enclosed in a fruiting body called a chasmothecium (pl. chasmothecia) (cleistothecium is a former term for this structure that is still widely used). The chasmothecium is generally spherical with no natural opening

Image
Epiphytic hyphae and chasmothecia on leaf surface. (Courtesy W. Gärtel)
Learning never ends because we can share what we've learned. And in sharing our collective experiences, we gain deeper understanding of what we learned.

User avatar
applestar
Mod
Posts: 27805
Joined: Thu May 01, 2008 11:21 pm
Location: Zone 6, NJ (3/M)4/E ~ 10/M

Re: Black Spots on Spinach Leaves

...what do you use for fungal issues in the greenhouse?
Learning never ends because we can share what we've learned. And in sharing our collective experiences, we gain deeper understanding of what we learned.

User avatar
MoonShadows
Senior Member
Posts: 150
Joined: Mon Dec 11, 2017 9:50 am
Location: Stroudsburg, PA - Zone 6a

Re: Black Spots on Spinach Leaves

Let me see if I am understanding correctly ....you (and the reference) are saying these black dots are the spores that will produce powdery mildew?

I have a container of Bonide 811 Copper 4E Fungicide which will treat powdery mildew, but since I don't expect this crop of spinach to be around much longer (the greenhouse is going to be getting too warm for spinach). I may just pick any leaves I find it on unless it starts to spread from those isolated plants.
4025b8a6-3583-468c-b634-93c672d68109_1.8773d473fe4445bc70c5836837edc44a.jpg
4025b8a6-3583-468c-b634-93c672d68109_1.8773d473fe4445bc70c5836837edc44a.jpg (25.76 KiB) Viewed 2295 times
https://MoonShadowsFarm.com Good Eats & Treats from the Pocono Mountains
"Go confidently in the direction of your dreams. Live the life you have imagined." ~Henry David Thoreau

Return to “Vegetable Gardening Forum”