How can I treat the blistering and curling oh my hydrangea? Appears on both lacecap and mop head plants?

Question

Leaves appear to have major blisters on the leaves with slight curling. One is in side yard, other in back yard. No insects appear under microscope. Thank you!

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Answer 1

The presence of pests may actually be a sign of another problem that is causing your plants stress. Insects that may trouble the hydrangea include aphids, leaf tiers, rose chafers, scale and four-lined plant bugs. Aphids distort the new growth and coat the leaves with sticky honeydew.

I would treat with Neem Oil, treat every 3 to 4 days for 2 weeks.

https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm