my lemon tree has been having some issues, its been dropping leaves all year at first i thought it might be a fertilizer deficiency and tried that. Been trying to rectify watering and soil conditioning but just not sure which way to go. Looking for any advice

Does it stay indoors all year?
Does the pot have a drain hole?

its outdoors in the summer, inside during the winter under a grow light. The pot has a drain hole in the middle. You think its root rot? Should i repot it you think its too far gone? Ive heard treating the roots with mycorhizzael fungus powder may be the way to go? Its just weird cause the other tree is doing pretty good and they were in the exact same situations. They get lots of sun in the summer almost like 10 hours they are in a wide open back yard and this year wasn't very wet so I augmented the watering like once every couple weeks with a deep soak, watering with a hose for like 2 mins a pot. The pots are kind of massive too 22'' wide and 28'' deep i think. Another issue i was having that I think after this batch of limes and lemons comes off the tree I need to prune the trees back and remove the support rod the trunks are too weak to support the weight of the trees.

Personally, I would want to keep the fruit on the tree...

I do think that it looks like it's been getting entirely too much water... and... bringing it indoors will always result some in leaf drop at my house.

I'm not sure that you'll be able to repot w/o losing lemons... How long has it been in that same pot?

At my house, I had one in the same pot for an ungodly length of time... 5 or 6 years, maybe longer... it was really suffering... set it out in the garden this last growing season... big improvement...

Personally, I'd stop watering for a month or two... see if that helped before doing too much else.

Edit:
just re-read your second post...
I wait until the end of winter before pruning... but autumn is my preferred time for repotting... I never do them together.

How long in the same pot and soil?
Soil can break down eventually, reducing aeration and drainage.
I have a distrust of big pots with one small hole. Really, almost don't like any pot with just one hole- they don't seem to drain/aerate very well for me.

I've had a lemon for a few years, it got scale and had a couple winters of losing about every leaf, then rebounding amazingly when back out for summer (I'm also in MD). So I don't think yours will die, but I'd be careful with water, and plan a rehab for early spring. My 2 cents.

If it was in essentially full sun all summer and you only watered it "every couple of weeks" when it didn't rain the problem isn't too much water, it was under-watered all summer. When I worked in nurseries we watered almost every day (we never had that 'rain' stuff). For a plant that big in that size pot, I would give it a good soak at least once a week if temps are 80 or above and it doesn't rain.
Sally's question about how long it's been in that pot is a great one. If it's brand new, then it can go longer between watering. If it's been in that pot several years, it will need more water until the leaves fall off (which they will). If it's in that window and getting supplemental lighting, once every 2 weeks would be about right. Of course, a deep probe before you water will let you know if it really needs it.

That plant has way too much fruit to support for it's size. You don't need to prune it, you need to let it grow more leaves, before you grow any more fruit. The tree is putting all it's resources into ripening those fruits, and not growing new leaves or roots.

Also no matter how large the pot is, you need to renew/refresh the soil at least once every year or two. Potting soil degrades and the organic elements in it are broken down and used up by the plant, or washed out by watering. The soil compacts and compresses the roots, as well as becoming much less water-retentive.

After the fruit is picked, I'd advise you to turn it on it's side and slide the whole root ball out of the pot. Wash off as much old soil as you can with the hose (maybe wait until the weather is warm) and then replace the soil with fresh, high quality potting mix being sure to fill in any air pockets.

Water thoroughly at least weekly, and about a month before it goes outside again, fertilize it with some citrus-specific fertilizer. It definitely needs water more often than every couple of weeks if it doesn't rain and the weather is hot, especially if it has fruit on it.