If you currently have or are looking to add lemon trees to your garden or landscaping, you want to make sure that you know how to properly care for and protect them. The leaves die and fall from the tree, which increases the tree's chances of being damaged by cold or attacked by other pests or diseases. Even citrus trees aren't immune to disease. As the fungus develops, the spots become visible on the leaf top. 3 years ago . Can you diagnose my potted Meyer lemon tree, which is now indoors over winter? Citrus trees are absolutely beautiful and one of the most popular is the Meyer lemon tree. Meyer Lemon Leaf Spots. This year the tree has black leaves and a few black lemons. Shelter lemons from cold winds with plastic, a screen or a hedge. When the tree is cold its roots are unable to absorb enough nutrients to keep the leaves green so they turn yellow. On the upper leaf surface, yellow spots turn into greasy-looking, raised dark brown blisters. Greasy spot is a fungus, known as Mycosphaerella citri, that affects the leaves of citrus trees and thrives in tropical and subtropical climates. The leaves have developed dark blotches that appear to begin on the underside and spread through to the top, along with some yellowing. HOPELR, May 27, 2007 #1. skeeterbug Active Member. Some leaves have dropped. Messages: 826 Likes Received: 10 Location: Pensacola, USA. Lemon trees prefer a warm subtropical climate, but grow in cooler climates if sheltered from cold winds and cold winter conditions. You probably have sooty mold--keep the leaf litter cleaned up and spray with a copper fungicide. Aphids consume the Meyer and leave behind honeydew (sticky, black soot) which then feed the ants. Greasy spot fungal spores germinate on the lower leaf surfaces and create blisters in the spots where they attack the leaf tissue. The tree grew well and we had many big & juicy lemons. They chew up entire branches of leaves and can leave your Meyer tree bare. If you notice huge chunks missing at a time, it could very well be a rodent or animal like a deer. There stood a small, sad looking tree that was pretty hard to spot as being a Lemon tree, because it was absolutely covered in a thick, black, sticky coating on all of it’s leaves. Skeet skeeterbug, May 27, … Michael. They work together to feast on your tree. This is why you may encounter pairs. (There is also a fungus gnat problem—not sure if that’s related.) Hello, I have a several year old potted Meyer Lemon that has developed some sort of ailment. Over the last couple weeks, it has gone from developing yellow spots on some of the leaves to dropping leaves. What happened and what should I do? Discover some of the most common Meyer lemon tree diseases below. Meyer Lemon Yellow Spots/Blotches on Leaves, Dropping. The fungus appears as yellow, dark brown, or black lesions that initially occur on the underside of mature citrus leaves. Asked January 19, 2018, 4:47 PM EST.