Hello and thank you for contacting Ask Extension. Have you had a soil test done? If not, that should be your first step. It’s not a good idea to put nutrients in your soil if your soil doesn’t need them. You can contact your local Extension Service office to see if they have soil test kits available or if you want to purchase one online, here is the website. https://homesoiltest.msu.edu/ The phone number for the Otsego County Extension service is<personal data hidden>. Their address is 800 Livingston Blvd, Suite 4A-2, Gaylord, MI 49735. It also looks like there is a MSU Extension office in Boyne City (319B N Lake St). Their phone number is<personal data hidden>. The soil test will tell you what nutrients and how much you should put on your red pine.

Do your red pine have some kind of a problem that you think is due to an insect? Without knowing what the problem is I can’t recommend something to fix it. According to MSU there are about “100 insects that are known to feed on red pine, but few represent major health issues. Several sawflies, the Saratoga spittlebug (Aphrophora saratogensis), Zimmerman pine shoot moth (Dioryctria zimmermani), red pine shoot moth (Dioryctria resinosella) and mound ants (Formica exsectoides) can sometimes cause problems. High densities of white grubs (several genera) can damage seedling roots. Several diseases occasionally damage red pine, especially Scleroderris canker (Gremmeniella abietina), Diplodia tip blight (Sphaeropsis sapinea) and Sirococcus tip blight (Sirococcus conigenus). Young trees are more vulnerable than older trees to rust, root rot and a number of other fungi.” If it’s an insect problem some kind of insecticide would be the recommendation. If it is a disease, some kind of fungicide would be the recommendation.

If you want to send in pictures I can try and diagnose what the problem is.

Here is a link to a couple articles about growing red pine.

https://www.canr.msu.edu/resources/forest_types_of_michigan_red_pine_e3202_9

https://extension.umn.edu/managing-woodlands/managing-red-norway-pine-forests