Substance On Ginkgo Tree Bark

Question

Does anyone knows what are these grey colour substance on the ginkgo tree?

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Answer 1

That is one of many Scale insects. You will have to remove what you can, manually, then spray with an insecticide.

Since they seal themselves to the plant, insecticide alone will not suffice.

Here are some articles for more information:

https://www.gardeningknowhow.com/plant-problems/pests/insects/control-plant-scale.htm

https://www.gardeningknowhow.com/plant-problems/pests/insects/what-is-armored-scale.htm

https://www.gardeningknowhow.com/plant-problems/pests/insects/what-is-soft-scale.htm