failing led floodlight killing grass

[chillinn]

That's plausible, except for the oval shape, which suggests something more traumatic, because why would only the grass in the oval die from missed rest cycles, but not the grass outside the oval, which also must have missed rest cycles. It's a floodlight not a spotlight, right? The purple tint is also a little too interesting to me, because I've seen LED shift to purple before, also.

But because I believe it was UV from a wavelength shift due to phosphor deterioration, and because I strongly supported my argument as the simplest explanation by the meager evidence given, and because nearly everyone here just can't handle the fact that I'm not always right but never wrong... then that definitely can't be the reason or we'll upset the children.

So it was possibiy missed rest cycles, because even though that is somewhere between unlikely and wrong for reasons and evidence i've provided, CPF's favorite son bykfixer suggested it, and he's far more well liked than I am, and I wouldn't have it any other way. People should get what they need, and if they need to be supported at all cost, then let them. To be clear, I could be correct, and bykfixer could be wrong, but because of feelings, science dies. Feelings are important, to be sure, but it'd be a better world if everyone stopped allowing their butt to be hurt anytime someone looks at it crosseyed, iow, don't hurt anyone is a good rule of thumb, but don't get hurt is complementary.

Also, there is a strong bias here towards LED never having any problems, so if the reason is a problem with the LED, that is also impossible for some here to accept. It's easier for them to believe it was a problem with the grass and biology.

At any rate, I stand by what I said, do not look into the light, turbodog. Hope you get a replacement soon and that your grass grows back, and in so doing exposes a large hidden cache of Spanish gold doubloons, and you have a big party to celebrate your good fortune and new ridiculous wealth, and invite everyone but me, so that I may remain a free thinking individual unswayed by fallacies of popular opinion and crowd think, and we all lived happily ever after.

 

[knucklegary]

Did someone mention purple spectrum?

 

[electrolyte]

What is the intensity of this light compared to sunlight? If a lot lower, there is less chance of any effect at all.

First, I really don't see how purple light would mess with the plants.

Second, note that mixing two colors to make a third is not the way it works. Plants use pigments at two different wavelengths to fix carbon and make sugar which is used to make everything that they make along with nutrients from the soil.

Chlorophyll a and chlorophyll b absorb light between 400 and 500 nm and 650 and 700 nm (two peaks for each, one in each range). Then, however, there are accessory pigments that fill in the gaps, B carotine being one. They must absorb photons and release them to chlorophyll at a lower energy. I don't remember the details. Off from those 400-500 and 650-700 efficiency is way lower. Consequently, light would have to be very bright to make any difference.

I like the way some of you are thinking. I am with kerneldrop, set up an experiment, move the light. Light attracting other things that are killing the grass, I like that, very probable.

I don't believe that turf grass plants need a rest period. This is also a testable hypothesis (science). Put a grow light out on the grass at night, you will obviously need to put it close to the grass. See if that kills it with the wavelengths that are known to stimulate growth. Here is another possibility that is also testable: if the light stimulate growth significantly,(but I don't believe it does) maybe the plants are using up the water in the soil there and drying out (live fast die young).

Meantime, contact your local land grant university, the plant scientists there, and tell them your observations and what you plan to do to test the various hypotheses. They may know some things that none of us know and have seen this before. If they have no idea, they should be interested enough to pay attention. This is not likely a revolutionary observation in plant science, but it could be. There is likely an extension office concerned with residential horticulture.

Hmm, Turbodog, Southern USA. I drink beer, local beer. How about LSU? Start here:
Horticulture Extension Personnel (lsuagcenter.com)

I am not a plant scientist, but I am a laboratory biologist who has worked in a lot of diverse fields over the years giving me exposure to that discipline. (As an example, I trained in a plant science institute for three years working on insect viruses, but I hear things and I ask questions of my peers.

 

[turbodog]

The world will never know...

Light has been replaced. Will see if grass fills back in. Good ideas though, although my interests are in non-biosciences.

 

[chillinn]

First, I really don't see how purple light would mess with the plants.

First of all, it wasn't purple light, because purple is not a spectrum color; it is additive, created from mixing blue and red in the RGB color space. turbodog used "purple" colloquially. It was violet light. Since the light is not a laser, it is not emitting a single wavelength of light, instead it is emitting a range of frequencies in a bell curve with violet at the peak (we presume, as it is possible light was peaking beyond the range of human vision and violet is just bleeding out at the edge of the curve, but for argument's sake, let's assume the curve was peaking in violet). Where is violet on the color spectrum? What are violet's close neighbors? Can excessive amounts of any of violet's close spectrum neighbors, even at low intensity, damage plants? Can you smell what the Rock was cooking?

The world will never know...

I am satisfied with my explanation. My curiosity exhausted, I have moved on.

 

[knucklegary]

Like Kitro said.. Photos?

 

[chillinn]

Like Kitro said.. Photos?

Here is a pretty good example of what bykfixer described

If I posted the images I have of turbodog's property, he'd probably get a little paranoid and stop strutting around shirtless in his skivvies, and I don't want to kill the golden goose.