Q.What Are the Brown Scaly Patches on the Underside of My New Lemon Tree
My 4 ft lemon tree was delivered 6 days ago to me in Maryland. It was indoors for 2 days and outdoors for 2. Brought it back in because the weather turned a little chilly. The tree is in the same container in which it was delivered. After 2 days inside again, it has developed light brown scaly spots, some 2 inches long, on the underside of leaves. A few of the leaves seem a bit curled, and one or two show the scales, but still green, on the leaf surface. I need advice as to what this problem is and how to stop it in its tracks. It has only been with me a short time, but I fell in love with the tree at first sight.

Since you've had the plant about a week, I would ask the shop from which it came. I truthfully don't know what would have developed that quickly. At first, I thought you might be describing the insect, scale. But you said it was 2'' long. Scale is about 1/4'' long. Are you putting it outside in sun for more than a couple hours at a time? If so, there is a chance it's sunburned. Remember the plant hasn't had direct sun for at least 2 weeks or longer. Here is a link to an article about growing lemons: https://www.gardeningknowhow.com/edible/fruits/lemons/growing-lemon-trees-containers.htm