Description
The health of many white pine trees across the northeast U.S. is declining due to a combination of poor environmental conditions, insect pests, and diseases. These factors can lead to symptoms such as yellowing needles, needle drop, branch death, oozing sap, and thinner canopies.
Many of New York’s white pines grow on land that was once used for farming and livestock grazing. These open spaces provide good conditions for white pine seeds to establish, allowing many white pines to sprout densely together. However, these sites do not provide ideal conditions for white pine trees as they grow. Past farming activities created poorly drained, compacted soils, which are difficult for white pine roots to grow through. In addition, densely packed white pines can become stressed as they compete for resources. These conditions make trees more vulnerable to pests and diseases, such as white pine needle damage (WPND), Caliciopsis canker, white pine blister rust (WPBR), and rot pathogens.
White Pine Pests and Diseases
White Pine Needle Damage (WPND)
WPND is caused by one or more of four native fungi. It can cause mature needles to turn yellow and brown in spring and drop by mid-summer. This can impact the tree’s health and slow growth; however, some trees can live with WPND for decades. In the past, WPND did not cause significant forest health issues. More severe WPND outbreaks were first documented in New England in 2006 and New York in 2013. These recent outbreaks are due to wetter springs and intense fall droughts caused by climate change.
Caliciopsis Canker
Caliciopsis canker is caused by a native fungus, Caliciopsis pinea. Spores from the fungus enter a tree through wounds or thin areas in the bark. Once infected, the tree develops cankers—or dead areas—on its trunk that ooze white streaks of sap, and branches begin to die starting from the bottom of the tree. Climate change may make Caliciopsis canker more severe because of increased rainfall in spring. A damp environment with little sunlight or airflow can increase the fungus’s ability to reproduce, worsening the effects of Caliciopsis canker.
White Pine Blister Rust (WPBR)
WPBR is a disease caused by Cronartium ribicola, a non-native fungus from Asia. The fungus was introduced to North America in the early 1900’s through infected white pine nursery stock from Europe. The fungus begins its life cycle on plants in the Ribes family, such as currants and gooseberries, before being carried by wind to infect nearby white pine trees. WPBR can be identified by yellow, blister-like fruiting bodies on the branches and trunks of white pine trees. These fruiting bodies, called aecia, emerge for a few weeks in spring before darkening in color and then disappearing. Other symptoms of WPBR include cankers; roughened, discolored bark; dripping sap; and needles that turn yellow and red. Cankers located on the trunk can cut off nutrients to the rest of the tree, causing the top of the tree to die. While older white pine trees can live with WPBR, it can be fatal to young trees.
Rot Pathogens
There are several rot pathogens that can affect white pines, including fungi such as procera, armillaria, brown cubical rot, and red ring rot. These fungi enter a tree through wounds in the roots, which can be caused by lawn equipment, construction, soil disturbance, and soil compaction. The fungi kill the tree’s roots, impacting its ability to uptake water and nutrients. Symptoms of rot pathogens can include yellowing needles, branches dying starting from the top of the tree, white mats or black shoestring-like growths beneath loose bark, and visibly decaying wood. Mushrooms growing on the trunk, on branches, or at the base of trees can sometimes be a sign of rot pathogens. However, not all mushrooms growing on trees are harmful or come from rot pathogens. Rot pathogens tend to be more noticeable and have more severe effects when the tree is already stressed from other impacts, such as drought, flooding, or construction.
Management
White Pine Forests
Since poor environmental conditions can lead to white pine decline, actively managing forests to create conditions that support strong, healthy trees can lessen its impacts. Removing individual trees to make a forest less dense, called thinning, can make white pine forests more resilient. Thinning reduces competition between trees for water, nutrients, and sunlight. This helps them grow faster and become more resilient to stressors like drought, extreme weather, pests, and diseases. Increasing airflow and allowing more light into the forest also reduces the ability of fungi to infect trees, making forests more resistant to diseases.
White Pine Trees in Yards and Neighborhoods
White pine trees planted in yards, neighborhoods, and community parks can also be affected by white pine decline. White pine trees need space and sunlight to thrive. Planting trees too closely together can create shade and moisture between branches, making fungal infections more likely. To improve the health of white pines in your yard:
- Consider thinning densely planted groups or rows to provide enough space so that branches of different trees do not overlap;
- Prune out dead or diseased branches regularly; and
- Avoid planting white pines in wet, poorly drained soils, as these conditions make root rot more likely.
If you are looking for recommendations on improving white pine health or if you notice problems with your trees, consult a certified arborist for management advice.
White Pine Research in New York State
White Pine Health Monitoring Plots
Since 2018, DEC has participated in a regional effort alongside researchers from Massachusetts, Maine, New Hampshire, Rhode Island, and Vermont to monitor the health and conditions of white pine. Funded by the U.S. Forest Service, this project will help us:
- Understand the extent of white pine decline across the northeast U.S.;
- Examine trends and areas of concern; and
- Identify new pests or fungi that affect white pine.
DEC collects data from 29 plots across New York on white pine growth, crown health, and severity of diseases affecting white pine. So far, this study has found that the severity of WPND and Caliciopsis canker has varied across New York each year, likely due to differences in precipitation at each site. In addition, white pine growth at these plots has been slow because of crowded growing conditions.
Demonstration Forests
DEC has established two demonstration forests to study how thinning can improve the health and regeneration of white pine. In Middle Grove State Forest, about 20 acres of white pine were thinned to remove about half the trees in one harvest. While forests are typically thinned more gradually to reduce the risk of trees falling over in strong winds—known as blowdown—this larger harvest will allow DEC to learn more about blowdown and regeneration after thinning. So far, blowdown at the site has been minimal. The second demonstration forest, consisting of 30 acres of white pine in Balsam Creek State Forest, was thinned using a more typical management approach. Rather than a single large harvest, half of the trees in the plot were removed in two stages. DEC will monitor both demonstration forests over time and compare outcomes, especially related to the trees’ wind vulnerability. The results will be used to inform landowners and forest managers about effective strategies for maintaining healthy, resilient white pine forests.
How You Can Help
DEC is collecting reports of poor health in white pine trees to better understand white pine decline. If you see symptoms such as yellowing needles, needle drop, branch death, oozing sap, and thinner canopies in white pines, please report them to DEC’s Forest Health Research Lab. Please note that some color change and needle drop is normal for white pines. In fall, a portion of older needles—those closest to the tree’s trunk—turn yellow or brown and fall off to conserve energy for next spring’s new growth. However, if a pine tree loses young needles or loses needles in spring or summer, it could be a sign of declining health.
To make a report to the Forest Health Research Lab:
- Take photos of the symptoms, as well as the tree's leaves, bark, and the entire tree.
- Email photos and location information to us at [email protected]. You may also call DEC’s Forest Health Information line at 1-866-640-0652.
