Plum tree bug

Hello,
I think i have a European plum tree but the new leaves are turning yellowish and turning in on themselves. On the underside of the leaf along the stem looks like white silk. What is it and can i help my tree
I think i have a European plum tree but the new leaves are turning yellowish and turning in on themselves. On the underside of the leaf along the stem looks like white silk. What is it and can i help my tree

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