Good morning,

We are so very sorry about your Mugo pine; it's always distressing to see a valued plant struggle. We suspect there could be several issues affecting it. 

It appears there may be a type of scale on your mugo. Plants are like people, in that when they're otherwise stressed, they're more vulnerable to insects and/or disease. Here is some information regarding different types of scale to consider:

https://extension.colostate.edu/topic-areas/insects/scale-insects-affecting-conifers-5-514/

Another consideration is the fact we had a very, very dry winter until our late-winter snows came. This information from the Univ. of Minn. is relevant to our area as well, and is good general information to have:

https://extension.umn.edu/planting-and-growing-guides/protecting-trees-and-shrubs-winter 

One simple way to check for adequate irrigation is to insert a screwdriver into the soil completely around any plant you're inspecting. If it slides in easily, there is adequate moisture. If you have to exert some force, you may want to increase irrigation.

As to whether or not your mugo pine will survive, we can't really say at this point. We would, therefore, highly recommend that you contact an ISA (International Society of Arboriculture) certified arborist to inspect it to see if there is an infestation of scale, as well as to  inquire about its survivability. Here is a list of recommended arborists:

https://bouldercolorado.gov/sites/default/files/2021-05/licensed-arborists-1-13-2021.pdf

If we can be of any further assistance, please don't hesitate to contact us.

Best regards, Boulder County Master Gardener Diagnosticians