What is up with this tomato leaf?
This is one of the two potted plants on my friend Catherine's deck in Minnesota, and while the plants appear to be generally healthy, they're nowhere near the size of the monsters I wrote about a few days ago, which were all in the garden proper. Only one of the potted plants shows this curious purple-bronze discoloration.
Want to see it again? Closer up?
Does anyone out there recognize this bronze color? I've been through about every diagnostic site I can find, checked out numerous forums, and nothing matches. There's a lot of stuff on the web about phosphorus deficiency causing purple leaves, but that's primarily the undersides and veins, and this is exactly the opposite: the upper side of the leaf, and everything but the veins. Furthermore, this is a very bronze purple. I've considered sun scald and cold damage, nutrient deficiency and fertilizer burn, and just to be thorough, alien invasions.
Here's a picture of a tomato leaf suffering from phosphorus deficiency:
Source: Aggie Horticulture (Texas A&M) extension
Not the same. In the course of my research (or bumbling around on the web) I discovered a brand new problem for tomato growers to worry about, and at first it seemed a perfect fit. 
BREAKING NEWS: In the midst of writing this post, while trying to find something about TPLD for 2010 (no success there) I found this photo:
Source: Citrus and Vegetable, 10/09/2009–cropped.
It's overexposed and has those weird dashed lines across it, but my gosh, does it look like Catherine's tomato or what? In the photo above, note that the the upper right portion of the leaflet has remained green. Vicki Boyd, author of the Citrus and Vegetable article, says that "Any part of the leaf that is shaded by other leaves or fruit remains green, while the portions in the sun will turn purple."
In my second snapshot above, the closeup clearly shows this phenomenon: parts of the leaf that are shaded by another leaf remain green. Okay, that's it: I've got to put these two photographs next to each other:
Anyone who read this post in its first hour up would have been treated at this point to a possibly libelous series of insinuations about big box stores and their probable role in spreading TPLD. I won't go so far as to disown those sentiments, but I do want to add that according to Boyd, researchers at the University of Florida believe that whiteflies transmit TPLD. So now I'm wondering about the life cycle, range, and longevity of white flies.
Does anyone out there know of something else that could produce the symptoms seen on this plant? If the leaves on Catherine's tomato look familiar–or if you're an experienced tomato grower and they don't–please weigh in. I'd greatly appreciate it.
Thanks.
(Edited and expanded.)
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I had my husband take a look, but he is stumped. Sorry!
Purple leaves usually means there is a phosphorus deficiency. However, since this is interveinal, I think that it may be magnesium deficiency. Check the fertility.
The leafs look very much like magnesium deficiency to me.
We had a similar problem two years ago. We used a magnesium fertilizer and the tomato plant made it through the whole summer. See in the second part of this post and in this post on our (german) blog.
Thanks anyway, Michelle. As The Clueless Gardeners, at least you're staying in character! And this way I got to visit your blog.
Thanks so much for stopping by, Toby. You and Heiner seem to agree that I'm looking at a magnesium deficiency. I have to say, though, that most photographs I've seen of that problem, including the ones you link to, Heiner, show splotches or lesions that I see no sign of in Catherine's tomatoes.
I have a question for both of you: would Mg deficiency lead to sun sensitivity? Would the shaded parts of the leaf stay green, as these do?
I will check the fertilizer that we used; it was formulated specifically for tomatoes, and I think it did include magnesium, but I'm not sure.
Thanks again for your suggestions.
–Kate
From how the leaves looked like, I really think that those tomato plants are suffering from phosphorus deficiency. The best way to deal with this is to find a fertilizer that has an adequate amount of phosphorus in order to help your plants survive and grow healthy.
If there has been a lot of rain then heat in Brugmansias (related to tomatoes) the leaf traps the water in some areas causing thinning of the tissues over the trapped water causing a weird sort of sun burn like that.
Just a thought.
Well, blossom enhancer, you’re certainly with the majority on this.
This is one I haven’t heard before, Chrissy. Thank you.
–Kate
Tomato plant gets distorted and changes into pale green. The veins of the fresh leaves become thinks and purple and these leaves attain a bronze color which is the symptom of Tomato spotter wilt virus and it is caused by aphids and thrips due to this, fruit gets infected with ringspots and distorts. So control them with an insecticides like malathion or neem.
Well, it is very common disease in tomato plants. I read in one blog, that Any part of the leaf that is shaded by other leaves or fruit remains green, while the portions in the sun will turn purple. Same issue I also seen in my tomato plants also.
The web site has only just been registered and the site will start construction shortly. In answer to your problem, I think I know what your problem is. I live in Guernsey in the Channel Islands and was famous for its tomato growing industry which has since died. BUT, I and a few friend who grow our toms outside have all suffered a very similar problem. It seems to occur after a long dry spell followed by heavy rain and a few days of prevailing damp moist air. It is an air borne fungal disease, You can cut out the diseased leaves if you still have a lot of fruit on the plant, but don’t compost the leaves and don’t compost the plants either. There is also a school of thought that you shouldn’t grow toms in the soild for at least two years. I may be wrong, but the colouring is very very similar. Do the leaves curl up?
Thanks for your excellent description. I am having the exact same difficulty with my tomato plants, which I keep in Earthboxes on my porch where they get good sun and steady water from their reservoirs. We have had a long drought here in Kentucky, followed finally by some rain, though not too much, and my plants were quite quickly taken over by exactly the purple/bronze leaf discoloration you described.
Because of the Earthboxes they’ve never had to struggle with cold soil, and right now they are fully mature, so I was not sure about the Phosphorus deficiency. I thought from the look of it that it was fungal in nature, as Mr. Womersley suggests (and the leaves DO curl up), so I sprayed them as soon as possible with a general fungicide Serenade. I also fertilized them with some liquid fertilizer for good measure, but they still seem to be hating it.
I was wondering what you attempted after gathering your information, and whether any of it worked??
Thanks very much!