A lot has been said about use of Epsoms Salts, magnesium sulphate, as a fertiliser and it is widely used. I've heard also that you can't over do it as high amounts won't have any adverse effects.

On the other hand, I've never heard of MSG being used as a fertiliser. As far as minerals go, it only contains sodium, and not a lot of that is needed by plants. What the glutamic acid would do for plants I don't know. But for people there is a widespread belief that it's harmful. I won't eat food that's got MSG as an additive (not knowingly, that is). But I've never asked any of my plants how they feel about it.

Hi
you made me realize how the MSG works
it is a very simple carbohydrate that breaks down very easily.
guess thats why people use it as a foliar spray, it will melt in water for the sprayer.

i just read an article about epsom salt, but about sugar also...
http://www.vegetariat.com/2013/01/gardening-secrets-epsom-salt-sugar/

sugar, probably works similar to MSG, a simple carbo...

MSG is actually used by big growers.
EPA has approved a crop spray called Auxigro
contains L-glutamic acid, an amino acid found in protein;
MSG has some other stuff in it i think, mostly D-glutamic acid, but to me, these are just amino acids, something your body needs and uses.
Some people hate the idea that (grocery) plants are being sprayed with it.
but it obviously works, otherwise the big growers wouldnt spend money on it.

in the heat, i think my papayas not only have a hard time taking up water fast enough, but i think the easy carbs in the MSG give them energy also.

good to know the epsom salts isnt toxic to them, ive been very careful, maybe too much so, to not use too much.

I don't know whether ".... otherwise the big growers wouldnt spend money on it" is a good recommendation. They tend to go for quick results rather than concern for long term consequences. I do use molasses, but only as a soil conditioner. It really gets the micro-activity in the soil going. And a little bit goes a long way. Don't know how it would go as a foliar spray, but it's great for cleaning engine parts, LOL.