I am guessing its a fungus. Use fungicide. I don't know of one so you'll need to google it.

Steve

Hi Chelsey, the brown is definitely fertilizer burn and the white is sunburn. When you go from greenhouse or houseplant to outdoors you need a few weeks of shade for the plant to adjust to the hot sun. For an action plan I would scrape off the top inch of soil and remove as much fertilizer as possible. Put the plant under an umbrella and water daily. The combination of heat, repotting, and fertilizer are not a good combination. Not sure the composition of the "soil" but most prepared soils/potting mixes have ample nutrients already in them. Also avoid putting the fertilizer to close to the crown next time. I grow sweet oranges and use a Blue Lab pulse meter to check soil EC before adding more fertilizer. Anything above 2.0 EC and my plants will show the same symptoms.

The cacti also appreciate the shade as many recently came from a greenhouse.

Thank you so much for the reply! Just moved the calamondin to a shadey part of my deck. She'll get sun in the am. I will look into the Blue Lab pulse meter! Question, do I need to remove the sunburnt leaves or should I leave them for now? I don't want to disturb the tree more than I already have and it's 80-90s during the summer days here in upstate NY... Thank you

I am in Toronto Canada so very similar weather. I would leave the leaves on. I water at least once per day in this heat. Infrared thermometer also helps identify if the roots are too hot.

Very helpful TY just saw you photo, so wonderful. I should have known better my 40 year old aloes that I took out recently all got a sunburn too, I am learning and fast! Ha.

Record temperatures today. Another option is to use a piece if burlap as shade cloth. With a tree planted in the ground the ambient air temperature and soil temperature are similar. With PVC and clay pots they can easily reach 20-30F hotter than the air if left in the direct sun. Some of your leaves are starting to curl. The plant does this to conserve moisture and slow down photosynthesis.

Removed a few aloe vera pups and replanted a month ago. They didn't have enough root and they burned up.

Ooo good idea on the burlap. I noticed I got more white on my leaves but not more yellow/brown spots.. hoping I can cure the sunburn, will these white leaves regain color?.. it's in afternoon shade now, I will make sure to water..