Hawthorn Tree - Leaves stunted and browning
May 26, 2020. We have an issues with our Hawthorn tree (we moved 1 yr ago so we think it is a Hawthorn, it had small cluters of white flowers in spring and in the late fall/winter there were red berries). In the last several weeks it appears to be sufferring from some type of disease or insect infestation. The leaves closest to the trunk are stunted and turning brown. The leaves at the very end of the stems appear normal size and green. The berries might have the beginning of fire blight but this looks different than what happened to our asian pear tree that sufferred from FB at our old house. There are also weird small flat centipede-looking black & orange insects on some leaves and berries. The stunted and brown leaves are very pervasive - almost the entire tree except for the very tips of the branches. The trunk bark also appears to have damage with long verticle strips cracking, dry, and peeling.
Prince George's County Maryland
This does appear to be a Hawthorn (Crataegus, perhaps the commonly-used Crataegus viridis 'Winter King'). Hawthorns are prone to spring outbreaks of leafminer, an insect larva that tunnels inside the leaf tissue and leaves dead, dry pockets at their tips in its wake. While drastic in appearance, they cause little damage to the tree and do not significantly impact it's health. The leaves with normal growth likely emerged after the leafminer feeding began, since they cannot move from one leaf to the next. No control measures are necessary and the damaged leaves will eventually shed and be replaced by new growth.
The developing berries are showing signs of the fungal infection called rust. This fungus bounces back-and-forth between two host plants (the other is a Juniper) and can be more prominent in springs with wetter weather. Despite being unsightly, it too does not require treatment (in fact, at this stage, treatments are not effective). More information on this disease is detailed here: https://extension.umd.edu/hgic/topics/rust-diseases-trees.
Peeling/flaking bark on several Hawthorn varieties (including 'Winter King') is normal. We cannot clearly see the trunk, but no obvious issues are visible. It does appear that the lawn grows up against the trunk base, which is risky with regards to mowing and weed-whacking equipment damaging the trunk. Ideally, a wide disc of mulch should be used at the base of the tree to prevent the lawn care personnel from having to come so close to the bark. Injury to the sapwood underneath the bark on the trunk base could cause serious irreparable damage.
The black and orange insect pictured on the hand-held leaf is a juvenile (larva) ladybug (lady beetle). They are beneficial predators of pest insects and should be allowed to patrol the plant. https://extension.umd.edu/hgic/topics/predators-ladybird-beetles-ladybugs
Thank you so much for this information! You are wonderful