Yellow leaves on Ulmus 'Morton Glossy'
Hello, I have a 12' Triumph Elm that was planted about 2 years in its present location in a new home development in NW Rochester. Over the past few days, I've been noticing some of the leaves turning yellow. The yellow leaves are mostly on the interior of the tree, while the majority of the leaves look green and healthy. There is new, healthy leaf growth that is still forming. The tree is in my front lawn which is well irrigated. About 3 weeks ago, I noticed Japanese Beetles on the tree and about 10% of the leaves showed beetle damage which I treated with "Sevin" (Carbaryl) applied in hose sprayer. A week later, I applied some diluted Neem oil with a pump sprayer after seeing the beetles return. For the past week, I have not seen any Japanese Beetles. I'm wondering if the yellow leaves might be an indication of stress caused by the application of insecticide, or perhaps the beetles themselves. I'm hoping it is not a sign of "Elm Yellows" (Elm Phloem Necrosis) or Dutch Elm Disease. Triumph is supposedly a DED resistant cultivar, but I don't know how much it occurs notwithstanding. I am hoping this is just some type of superficial thing, but I'd appreciate any educated input you might be able to provide. Many thanks!
Olmsted County Minnesota