Stressed out Key Lime? (w/pics)
Last spring I bought a Key Lime tree (Semi Dwarf Five Gallon) that was, I believe, 2-3 years old (4-5' tall). This is my first citrus tree so I wanted to start easy (e.g. not from seed). I live in Minnesota and kept it outside for the first summer then moved it inside in the fall and entire winter. While both outside and in the plant did great - it showed new growth and produced a 10-12 key limes over that first year. It looked, to my untrained eye, to be a completely healthy plant. Near the end of the winter, however, it started to look a little less healthy. It wasn't as green and dropped some leaves. Nothing too alarming, but a noticeable change. As luck would have it (or so I thought) we've had an unseasonably warm spring and being the rookie I am I thought "hey, I'll move it outside and the sunny 70 degree weather will perk it right up". Wrong. After moving the tree outside into direct sunlight (with no acclimatization) it has taken a turn for the worse (pictured below). Brownish spots on leaves, some leaves yellowish, leaves sagging more than usual and starting to fall off. After reading fairly extensively on this message board it appears I might have put it into shock by dramatically changing its environment. The weather has been pretty stable (50s-80s) some rain, plenty of sun - nice, but a lot different than its indoor sun exposure/temperature. I don't believe it's the watering, soil or nutrients alone as it changed so quickly after a year of being ok. I've looked for pests and cannot see any. I also checked the roots and they don't appear to have any rot (very slightly wet, white in color).
So if the experts out there take a look at the pictures do they look in line with environmental shock? Is it something else I should be worried about? The tree just looks so unhealthy right now it's deflating. If it is environmental do I simply move it into a shadier area to acclimate it better? Move it back inside? Any advice is greatly appreciated.