Why are the leaves turning brown on my Sunburst Locust tree?
Question:
Some branches of leaves are turning brown on my Sunburst Locust tree. There are no webs so I’ve kind of ruled out the webworm. What could be causing the problem?
Answer:
There are a number of reasons why tree leaves can brown, both biotic (e.g., pests and pathogens) and abiotic (e.g., environmental such as serious drought or heavy soil compaction), and we may not be able to diagnose the problem from your photo, but I will run through some of the possible culprits.
For pests and/or pathogens, if we rule out webworms (I agree, I don’t see any evidence of webbing), my first thought is locust leafminer–the brown, crispy tissue on the foreground leaves isn’t exactly the way the damage typically appears, but the stipling on the greener leaves has me wondering about some kind of foliar feeder. Also, though I don’t see any evidence of canker damage, the photo isn’t showing much stem tissue, so I would check the branch crotches and trunk for signs of cankers or root collar rot, which can exhibit dying foliage as an early symptom. If you see any clear evidence of insect activity or stem/trunk damage, you can send in more photos and we can try to identify/diagnose.
For environmental issues, I’m less concerned, as honeylocusts are tough trees that can weather just about any conditions . That said, having your soil tested periodically and maintaining consistent watering can help keep the tree vigorous and healthy.
Happy gardening.