Hi Erin,

Thank you for contacting the UNH Cooperative Extension Infoline with your request  for advice about your aging pine tree which is dropping branches and needles.  You also mentioned that your home is in a shore land zone.

I have included a link to a book, Landscaping at the Water's Edge:  An Ecological Approach, prepared by UNH Extension that may be helpful.

https://extension.unh.edu/sites/default/files/migrated_unmanaged_files/resource004159_rep5940.pdf

As we discussed on the phone, I have also included a link to the NH Arborists Association webpage which includes a list of arborists certified by the association.

https://www.nharborists.org/

I neglected to ask which type of pine you have.  However I have included information about white pine needle cast that has become apparent this year.

We have received many inquiries recently regarding white pine tree issues - specifically that pine needles that are turning yellow/brown and shedding prematurely. What you are observing in your landscape is most likely known to as: white pine needle disease (WPND;) also referred to as needle blight or needle cast disease.

The dieback in needles is caused by fungal pathogens that favor moist, humid environments. Last summer, we received a significant increase in precipitation during the months of May - July, the same time when white pines are flushing new growth. A combination of increased rainfall and warming temperatures promotes an environment for disease development and spread. The fungal pathogens that primarily cause WPND are: Lecanosticta acicola (formerly Mycosphaerella dearnesii), Septorioides strobi, Bifusella linearis and Lophophacidium dooksii (formerly Canavirgella banfieldii). These pathogens rarely kill the pine trees themselves, but if the cycle of infection and other environmental stresses persist in consecutive years, trees can severely weaken over time.

White pine needles typically have a three-year cycle and seasonally shed their 2- and 3-year-old needles in late summer/early fall. The browning and premature drop of diseased needles that you are observing now are of one-year-old needles emerged from last year (NOT emerging needles this year,) with the peak occurring around mid-June. If your tree(s) show any other signs of stress or have experienced needle blight frequently, their overall health could be impacted. If this is the first exposure to this disease, the tree should be able to counter the effects of WPND this year and recover.

Here are a few resources to read more:

UNH Extension - White Pine

https://extension.unh.edu/resource/dieback-eastern-white-pine-pinus-strobus-pathogens-pests-changing-climate

NH Bugs - Native Insects and Diseases

https://www.nhbugs.org/damaging-insects-diseases

Society for the Protection of NH Forests - White Pine

https://www.forestsociety.org/blog-post/forestry-focus-whats-wrong-tree

UMass Extension - Dieback of Eastern White Pine

https://ag.umass.edu/landscape/fact-sheets/dieback-of-eastern-white-pine

To address the white pine needle cast issue, we also recommend sending a sample into the plant diagnostic lab at UNH Extension for a positive diagnosis. The link below provides the homepage, including the address to send the sample. The submission form link provides best practices for submitting the plant sample as well as other resources.

Link to homepage: Plant Diagnostic Lab Homepage

https://extension.unh.edu/agriculture-gardens/pest-disease-growing-tools/plant-diagnostic-lab

Link to the submission form for a plant diagnostic sample: UNH Plant Diagnostic Lab

https://scholars.unh.edu/cgi/viewcontent.cgi?article=2506&context=extension

You may also consider reporting your observations to NH Bugs: Reporting Form

Here are also a few fact sheets about pines.

https://extension.unh.edu/blog/2019/10/why-are-my-evergreens-shedding-yellow-brown-needles

https://extension.unh.edu/blog/2021/10/fall-pines-too