Leaf cupping in a mulberry tree

Asked August 17, 2018, 1:09 PM EDT

We have a few mulberry trees in our yard, and lately we have noticed that two of them have leaves that seem to be cupping. One of them is only partial, while on the other the whole tree seems to be affected. Is this an insect or disease? If so, how do we treat it (if necessary) I have attached a picture of the affected tree. Thank You!

Ramsey County Minnesota shrubs diagnosis of plant problems

1 Response

Thank you for the question. Diagnosing plant problems requires that the entire plant be thoroughly inspected. Check trunk, branches, tops and bottoms of leaves to look for signs of insects or diseases. Examples of what you might find are webs, lots of one kind of insect, sticky honeydew substances, insect droppings or maybe disease signs like fungal spores (powdery or fuzzy structures). Spider mite or aphid infestation can cause cupping of leaves but you might also see some webs in the case of spider mites and sticky honeydew in the case of both. Plant damage can occur for non-living reasons too, like herbicide injury, drought, lawnmower or weed whip and so forth.
If you don't find anything suspicious when you inspect your trees and you have been caring for the plants properly, a possibility is herbicide damage. Products used to fertilize, control weeds or insects in lawns can "drift" onto your plants from your yard or even neighboring yards and have unintended consequences. The fact that some plants are unaffected and others only 1/2 damaged, and the uniform cupping of the leaves lead me to think it might be a chemical injury.

This type of damage is difficult to diagnose. We don't know how your trees will recover. If it is herbicide damage, continue to water them well until the ground freezes and hope for recovery next year.

If you find other signs of problems and don't think herbicide injury is possible, please submit your question again with good, closeup photos of insects or signs.

Thank you for contacting Extension.