My aloe vera plant is having black and brown spots. Help me figure it out .
Aloe, Gasteria and Haworthia can all get black spot like black spot you find on roses. Black spot is growing on your plant because the conditions are perfect for the disease. If water is allowed to get the foliage wet. If not that then it is probably air circulation. The area is too humid. You need to get a fan in the area where you grow the plant. Make sure the plant is not jam packed against other plants or in the corner of the room. Sometimes black spot is caused because the plant is stressed. Black spot does not tend to attack otherwise healthy plants. Unless the conditions are perfect. I can tell from the colour of your Aloe that is not getting enough sun. If it is winter where you are (Northern Hemisphere) it should be in a window facing south. In summer it also should be in a window with lots of sun or outdoors in the sun. In summer, still Northern Hemisphere, it can be East, South or West location, but never North. In Southern Hemisphere it should be in the West, North or East location in summer and a Northern window in winter. The more sunlight you can provide will be the best. If you plant is healthy it is less likely to get black spot.
You also need to water less in winter. The plant should be watered then allowed to dry completely out, letting it stay dry until is start to show stress then water again. Some people will let it dry out and stay dry for awhile, but not long enough to show stress. Whatever you do. Water less in winter.
Remove any leaves that are more black spot than green leaf. You can also trim the end of the leaves off. All of these cuts need to stay dry as the heal over. They need to stay out of the rain or get water in those open wounds you will be creating. As the plants gets large continue to remove the infected leaves until all the leaves are removed.
You could cut off all the black spot leaves, keep the plan clean and health and it will grow back new clean leaves soon enough.
Do either of the above and spray with a a fungicide. If you are planning on using this Aloe as a treatment for cut and burns, you should be careful on what you spray.
I personally would spray & do number one of the above, remove the most infected leaves and try to trim off as much as I possibly can. I would not remove all the leaves, but I would treat all the black spot with a fungicide. You need to kill the black spot to keep it from spreading. and keep it healthy.
In the best case senerio if you keep the plant healthy the black spot will not spread, but if the factor at all are not ideal, the black spot will spread if not sprayed. You can use something safe like copper. You do not need to use non-natural fungicide. There are options.