On keeping your trees healthy
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| URI’s Plant Diagnostic Laboratory assesses symptoms of beech leaf disease and other plant issues. (URI Photo / Keiddy Urrea-Morawicki) |
A forestry extension specialist at the University of Rhode Island, Christopher Riely works with faculty and students across campus, and off-campus partners, to help improve Rhode Island’s forests and the wildlife they support. A certified arborist and forester, Riely answers some questions about local trees for Arbor Day which was on April 24.
Do you have any tips for tree safety for residents — things to check for tree weakness after the winter, or safety tips for home yard work as people start getting out in their yards more?
The early spring before trees have fully leafed out is a
good time to check for damage that trees may have sustained over the winter.
However, as bark is more easily damaged during this time of higher sap flow,
pruning at this time can make trees more susceptible to disease. The dormant
season is the best time for pruning, especially the late winter when cuts will
heal soon thereafter when trees start growing again.
April and May are good months for planting trees and shrubs so they can start to get established before the hot summer months that usually bring drought stress. Planted trees should be watered regularly at least through their first growing season in a new location. While it’s best to avoid planting during the summer months, larger trees, such as those that come from nurseries balled and burlapped, can be also planted in the early-to-mid fall.
Is there anything homeowners can do to help protect trees from pests such as the emerald ash borer and/or spotted lanternfly?
Exotic invasive insects and diseases are an ever-increasing
threat to forest ecosystems and trees. Long-present pests such as the spongy
moth (formerly known as gypsy moth), chestnut blight, and Dutch elm disease are
still with us. Hemlock woolly adelgid (an aphid-like insect whose egg masses
are visible on the underside of needles during the winter months) has become
well established in Rhode Island and the emerald ash
borer (a tiny, brilliant green wood-boring beetle) is leading to the
mortality of many ash trees.
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| URI’s Biocontrol Lab partners with the RI Department of Environmental Management to monitor and research forest health pests such as the spotted lanternfly. (Photo courtesy R.I. DEM / Alana Russell) |
Within the past several years, almost all of the state’s beeches have become affected by beech leaf disease and some of them are impacted by beech bark disease as well. The brilliantly-colored spotted lanternfly moth has now been found in all counties in the state, although populations are still concentrated in the Providence metropolitan area. Primarily an agricultural pest, its preferred host is the common invasive tree known as Ailanthus or “tree of heaven.”
The Southern pine beetle, which has migrated northward into
Rhode Island due to warmer winters, is one of the newest forest pests to look
out for. It is a tiny black bark beetle which primarily attacks pitch pines
locally; one of the telltale signs of an infestation is popcorn-like patches of
sap on the bark of the tree. Meanwhile, sassafras trees are susceptible to a
disease called laurel wilt transmitted by another beetle; it was found in the
Northeast for the first time last year.
One of the best things that landowners and homeowners can do is to be aware of and learn to recognize these forest pests and diseases. URI’s Plant Diagnostic Laboratory and Biocontrol Laboratory are working with the Rhode Island Department of Environmental Management Forest Health Program and USDA Forest Service to monitor and research strategies for managing them; the specifics are different for each individual insect or disease.
In general,
there are often treatments (some of them experimental) that can be appropriate
for small numbers of trees, such as in a yard, but are impractical or
cost-prohibitive at a forest scale. For Southern pine beetle, thinning pitch
pine stands has been shown to be an effective method of preventing or
mitigating infestations.
Are there places in Rhode Island you recommend to enjoy
spring blooming trees?
Some of the best places to see spring blooms are in public
park spaces, where communities have intentionally planted blooming trees that
people find beautiful and appealing. Many of these trees are non-native (but
not invasive species), with ornamental apples, cherries, and pears being among
the most popular with their pink and white blossoms.
Here at URI, one of the best places to see blooms and a
variety of different types of trees is in the Botanical Gardens located
near the northeast corner of campus (on Greenhouse Road, off Upper College
Road). Although there are fewer trees, another good spot is the Youngken
Medicinal Garden located adjacent to Avedisian Hall that is part of
the College of Pharmacy. It contains nearly 300 species of medicinal plants,
including a seating area with river birch trees.
White-blooming dogwoods can be found in the understory of
forests all around the state. The tulip tree or tulip poplar is one of our
tallest native trees, so its blossoms are often far overhead, but it has large,
distinctive yellow-green flowers with an orange band at the base that appear in
May and June. Tall mountain laurel and rhododendrons (admittedly shrubs) are
common in some areas of western Rhode Island such as the scenic Long and Ell
Pond area in Hopkinton where there are popular hiking trails.
While it’s located in a more remote part of the state,
Rodman’s Hollow at the south end of Block Island is known for shadbush that
grows to the size of trees as there is little competition from other trees. The
white blooms in May there are quite striking!
For more tips on tree selection or care, contact URI’s
Cooperative Extension Gardening and Environmental Hotline (401-874-4836 / gardener@uri.edu) or visit Rhode Island Woods,
an online resource for information on Rhode Island forests, maintained at the
University of Rhode Island.
