Ms. Black,

Without seeing your trees, it is difficult to make a correct diagnosis of the problem that is troubling you.

Would you please send us 3 photos of your plant: one closeup of the affected needles, one of branches and then step back to show your tree in its environment.

Your trees may be infected with any number of problems, including scale, which can be quite serious. (Source: Manual of Woody Landscape Plants, pp. 735 ff. by William Derr.) You can see what scale looks like here: https://extension.colostate.edu/topic-areas/insects/scale-insects-affecting-conifers-5-514/

However, you may have nothing to worry about. The secret to the survival and success of coniferous trees, including your Mugo pines) is the waxy coating of their needles. Also coniferous trees (unlike deciduous trees) do not shed their leaves (needles) annually, but only every few years. See https://ssec.si.edu/stemvisions-blog/closer-look-fall-foliage (A Smithsonian publication).

But we cannot make a correct diagnosis and, perhaps, suggest a remedy, without seeing your photos. We look forward to seeing your photos soon.

One other thing to consider as a reason for the browning: Water. Here in Colorado, life is tough for trees—what with our drying Colorado winter winds, lack of snow cover, wildly fluctuating temperature (two weeks ago!) and low soil moisture. Read more about it here: https://planttalk.colostate.edu/topics/weeds-cultural-problems/2129-winter-desiccation-evergreens/

We look forward to seeing your photos, so we can make an accurate diagnosis and make suggestions for treatment, if necessary.

Thank you for contacting the “Ask Extension” program.

Sue, Weld County Colorado Master Gardener

Heather

Thanks for sending photos of your tree.

After reviewing the photos, it appears your tree has Pine Needle Scale. It also appears to be under stress, which may be caused by environmental conditions such as lack of water and weather conditions. You shared the link (: https://extension.colostate.edu/topic-areas/insects/scale-insects-affecting-conifers-5-514/) to CSU Extension fact sheet on Scales Insects affecting conifers. The section of the factsheet titled Pine Needle Scale Control provides information on natural and insecticides which may be used to control scales. The natural methods (minute lady beetle (Coccidophilus atronitens) or parasitic wasps) may not be preset in your area. If you choose to use an insecticide, be sure to apply it at the appropriate time of year.

I hope this information is helpful.

Linda, Weld County Colorado Master Gardener