View Single Post
Old March 21, 2018   #59
bower's Avatar
Join Date: Feb 2012
Location: Newfoundland, Canada
Posts: 6,793

Originally Posted by Tiny Tim View Post
bower, I'm seeing the same poor results with my new shop light LED. It's NOT the same as my full spectrum LED's. Maybe the plants just need more time to adjust, or I'm expecting to much from a 40 watt fixture.Like you mentioned, mine is also in a cooler room and it puts out very little heat.
Well this morning I decided to get to the bottom of it. Took pics, took off leaves checked undersides, didn't find an insect cause so I did a google for tomato leaf edema (the term "intumescence" is also applied to this physiological condition) and guess what. Light spectrum issues came up right away.

"..Recent research indicates that light quality, specifically ultraviolet-B (UVB) radiation is directly related to preventing or minimizing intumescence symptoms on ornamental sweet potato and tomato,.."
Far-red and Blue Light Synergistically Mitigate Intumescence Injury of Tomato Plants Grown Under Ultraviolet-deficit Light Environment
Yes, the text refers specifically to LEDs

Attached below, a graphic of research results from:

And pics of the edema on my tomato leaves. One interesting thing, they say susceptibility varies by cultivar and for me, there were more-less-and not affected plants in each group of F3, F4 etc so I could make this a point to select away from that susceptibility.
I'm satisfied that the LED shoplights are good enough for greens. I could probably make them usable for tomatoes by hanging the light in one of my window spaces, so they get natural light as well. Will have to look at my plant shuffle options and decide what to do...
Attached Images
File Type: png tom-edema.png (100.9 KB, 140 views)
File Type: jpg leaf-edema.JPG (427.0 KB, 142 views)
File Type: jpg leaf-edema2.JPG (318.5 KB, 144 views)
bower is offline   Reply With Quote