I have a lovely Golden Chain Tree, but every year around this time, after the blooms have ended, the leaves start to turn yellow and the tree looks “sick”. I saw tiny white insects just now on the underside of the leaves and suspect they may be the culprits. Do you have any idea whether that’s the case and if so, what are these insects and can you recommend a course of action to slaughter them? (The tree is way too tall to reach the top with a garden hose if I were going to try to blast them off with water.) Many thanks in advance?
Golden Chain trees (Laburnum spp.) are beautiful and I understand your concern about yours. They are subject to attack by aphids and mealy bugs. In your case, the photo you provided is almost identical to this picture of aphids, this time on tulip trees. You may notice the sticky “honeydew” they produce and see ants climbing the tree to eat it. Usually, aphids on trees will not cause the death of the tree, but the honeydew can contribute to the development of sooty mold which, in addition to the yellowing leaves you noted, can be very unsightly, However, a heavy infestation can cause premature leaf loss and thus weaken the tree. In addition, aphids can spread viruses.
And you are right that, normally, we would recommend a strong spray blast from the garden hose to wash off the aphids. We also recommend spraying with insecticidal soap. However, your tree’s size makes that difficult for you to carry out, yourself. For that reason, I would suggest that you contact a certified professional arborist to examine the tree, confirm the diagnosis and provide a solution. You can find a local certified professional arborist, through the International Society of Arboriculture here.
For further information, you might like to review the responses we provided other inquirers about aphids on their linden and aspen trees.
Finally, in terms of the overall health of the tree, note that they really prefer dry soil, especially in winter. If there is poor drainage or excessive moisture where the tree is growing, you may have an additional problem to discuss with the arborist.
June 29, 2024