Asked December 07, 2020, 4:20 PM EST
Eaton County Michigan
The first management strategy for any concerned homeowner is to hire a licensed, certified arborist to view the trees.
To Find an Arborist, click on this link: https://www.treesaregood.org/findanarborist/arboristsearch
Cultural management of eastern white pine should focus on increasing light, particularly to lower canopy branches. White pine requires full sun to thrive and if branches are shaded by overstory or neighboring trees, they will decline over time. Needle blight fungi prefer wet and shaded environments and often develop on interior sections of lower canopy branches. Direct sunlight will dry needles and branches faster and reduce the time needle blight pathogen spores have to germinate and invade.
Additionally, light-stressed branches can be preferentially attacked by opportunistic pathogens and insects. If white pines are growing in a dense grove, consider thinning to allow the residual trees a chance to grow outward, which can improve vigor.
Chemical management may be helpful in select cases, such as young trees that were recently transplanted and suffering from establishment stress or white pines planted and pruned as a screen. However, many white pines in the landscape are too large to effectively treat with fungicides and harbor such high levels of inoculum (diseased plant parts that harbor a pathogen, allowing it to overwinter and sporulate) that no amount of fungicide will control the disease. If needle blight from a fungal pathogen has been confirmed, the following fungicides are recommended for use against the four most prominent needle blight pathogens (Lecanosticta acicola, Lophophacidium dooksii, Bifusella linearis, and Septorioides strobi) and are registered for use on ornamentals in Massachusetts (In Michigan, check the label):
Your tree service and arborist should also know this information - READ THE LABEL - THE LABEL IS THE LAW
Azoxystrobin • Chlorothalonil (Restricted Use) • Chlorothalonil + Thiophanate-methyl (Restricted Use) • Copper Salts of Fatty and/or Rosin Acids • Copper Hydroxide • Copper Hydroxide + Mancozeb • Mancozeb • Phosphorous acid • Thiophanate-methyl For larger trees, a lower bole drench with Phosphorous acid + Pentra-Bark may help to slow the decline. This broad-spectrum fungicide is highly systemic but the thick bark scales of eastern white pine may prohibit penetration into the vascular tissue. As mentioned above, environmental stresses are a likely contributor to the current decline. In addition to needle blight, there are many other potential insect pests or fungal pathogens that could be responsible for the current symptoms. Therefore, numerous factors must be considered to create an effective management strategy for declining eastern white pine. (That is why you should consult with an arborist)
Reference: Management recommendations for eastern white pine (Pinus strobus) with symptoms of canopy decline Nicholas J. Brazee, Ph.D. University of Massachusetts Extension Plant Pathologist Click on this link: https://ag.umass.edu/sites/ag.umass.edu/files/content-files/alerts-messages/white_pine_management_recommendations.pdf
Other resources and references:
Dieback of Eastern White Pine (Pinus strobus): Pathogens, Pests and a Changing Climate - University of Massachusetts
Click this link: https://ag.umass.edu/print/20482
Pine Diseases- Penn State University - Link: https://extension.psu.edu/pine-diseasesMassach
Hope this helps!!