Trees and shrubs aren’t the only plants you need to protect in winter. You also need to protect your houseplants. While houseplants aren’t subject to the same harsh elements your trees and shrubs are, the winter still impacts them. Even your year-round houseplants will feel winter’s bite. So, you’ll need to treat these plants differently during winter than at other times.

But first, do some research on your plants.

Find out their winter needs. Some species will require more specialized care than others during winter. Knowing your plants’ special needs enables you to provide the care they need to survive the cold. In general, try to imitate the winter conditions of the plants’ native areas. Mimicking their native habitats boosts their chances of surviving dramatically.

Simple Steps to Help Your Plants Survive the Winter

Plants get less sunlight in winter than in the other seasons. Less sunlight triggers a plant’s natural dormancy, so it uses less water and grows less. This process can stress plants. Taking the simple steps listed below will keep your greenery healthy in winter:  

1. Adjust your watering schedule. Water your plants deeply, but only when the top inch of soil is dry.

• Move your plants to a brighter spot. Move your plants to a south- or west-facing window where they’ll get direct sunlight for at least 6 hours daily. Use a grow light if necessary.

• Increase the humidity. The air in our homes is often drier in the winter than at other times, which can stress plants. So, group your plants together to increase the humidity around them. You can also use a humidifier.
• Avoid drafts and cold air. If possible, keep your plants away from cold drafts, radiators, and air vents. Sudden temperature changes can shock plants, causing them to drop leaves.
• Fertilize less often. Many houseplants don’t need to be fertilized in the winter. If you decide to fertilize your houseplants, use a half-strength solution monthly.
• Look out for pests and diseases. They’re more common in the winter when plants are stressed than at other times. Inspect your plants regularly for signs of pests or diseases. Treat them immediately if necessary.

• Be patient with your plants. Houseplants will lose some leaves in the winter. Don’t be alarmed if your plants look less lush in winter.  

Following these tips can help your plants survive even an extreme winter. With extra care and attention, they’ll emerge from winter ready for spring.

Plants that Thrive in Winter

Plants aren’t all the same, however. Some do better in winter than others. So, another consideration is having houseplants that thrive in this season. Below are several plants that can add interest and color to your garden or home during a cold, snowy New England winter.  

• Winter aconite: This yellow flower blooms in late winter or early spring. It will even bloom through snow. It’s a low-growing, easy-to-care-for perennial.   
• Snowdrops: These delicate white flowers bloom in late winter or early spring. They’re a good option for naturalizing in woodlands or meadows. 
• Snowdrops flower
• Pansies: A versatile annual plant that can be grown in pots, borders, or hanging baskets, pansies bloom in various colors including white, purple, yellow, and orange.
• Violas: Violas are similar to pansies but smaller and have more delicate flowers. They bloom into early spring.

Violas in bloom

• Cyclamen: A popular winter pot plant, cyclamen produces heart-shaped leaves and delicate flowers in shades of white, pink, purple, and red.

• Witch hazel: Witch hazel is a large shrub that blooms in late winter or early spring, producing clusters of fragrant, yellow flowers.

• Hellebore: Hellebore, also known as Christmas rose or Lenten rose, is a perennial that blooms in midwinter. It produces cup-shaped flowers in shades of white, pink, and purple.

New England winters can be tough on greenery. It’s a time when plants go dormant. That can stress a plant. But taking the simple steps described above gives your houseplants a good chance to survive the winter. Choosing a houseplant that’s native to the area in winter is another option that many people take.

For more information on steps you can take to keep your houseplants surviving and thriving in winter, contact RITree.

Are your young trees all set for winter? Winter in New England is hard on trees—especially young ones. So, late fall is the perfect time to start preparing young trees for the harshness of winter. This process includes protecting the bark of young trees. It often splits in the winter and can leave young trees vulnerable. Splitting is typically more severe on young trees’ south and west sides than on the north and east sides.

This splitting process is called sunscald. It occurs when the sun’s heat damages tree bark. That creates a temperature difference between internal sapwood under the bark (hot) and the external environment (cold). That, in turn, causes the sapwood to desiccate, shrink, and die. The bark eventually cracks along the dead sapwood’s fault line. Young, thin-barked ornamental and fruit trees. like birch, stewartia, red maple, London planetree, and beech are especially susceptible to sunscald. 

This red maple is showing signs of sunscald, which can devastate a young tree in winter.

Sunscald occurs in summer and winter, but it is much more common in the winter. Hence, the need to start protecting young trees in the fall from this winter increases. Symptoms of sunscald include:

• Dead or discolored bark
• Vertical cracks in the bark
• Bleeding from the affected area
• Sapwood (the layer of wood just beneath the bark) that is exposed

Young trees can survive sunscald. But even if they survive it, sunscald can weaken young trees, making them more susceptible to other problems, such as pests and diseases.

Young Trees are More Susceptible

Cold weather, snow and ice, drought, salt spray, pests and diseases can severely damage trees. So, can sunscald. It can devastate them. Here are a few reasons why young trees are more vulnerable than older ones to sunscald:

• Thinner bark: Young trees have thinner bark than older trees. That’s because the tree bark thickens over time as the tree grows and ages. Thinner bark is more susceptible to damage from the sun’s heat.
• Less developed canopy: Young trees have less developed canopies than older trees. That means they have less foliage to shade the bark of the trunk. Less protection increases the chance of sunscald.
• Less experience with sunlight: Young trees have less time to adapt to sunlight than older trees. That makes them more susceptible to damage from the sun, especially if they are suddenly exposed to more sunlight than usual.

• More exposure to direct sunlight: Young trees are more susceptible to sun scald if planted in an area where they are exposed to direct sunlight for most of the day. That’s especially true in wintertime when the sun is lower in the sky than at other times, and the tree’s bark is more likely to be exposed to direct sunlight.

Protecting Young Trees from Sunscald

Tree owners can do a lot to prevent sun scald from occurring—even in the harshest New England weather. To protect young trees from sun scald, you can:

1. Wrap the young tree’s trunk with a white tree wrap or plastic tree guard during the winter. The wrap reflects the sun and keeps the bark at a more constant temperature.
2. Plant young trees where the elements protect them from the winter sun. The site could be in the shade of a building or another tree, or on your property’s north or northeast side.
3. Water young trees regularly, especially during the first few years after planting. Watering helps them to develop a robust root system and withstand winter stresses.
4. Mulch around the base of young trees. This step insulates the roots and protects them from the cold.
5. Prune your trees in the late fall or early winter. This action will help to remove any dead or diseased branches that could be more susceptible to sunscald.
6. Plant young trees in a location that protects them from the sun and wind, in the shade of a building or another tree, or on your property’s north or northeast side.
7. Look out for pests and diseases. If you see signs of them, contact a certified arborist or RI Tree for advice.

Following these tips on combating sun scald can help protect your young trees from this sunscald and ensure they thrive for many years.

For more information on sunscald or tree care contact RITree by e-mail at ritree@ritree.org.

The American chestnut tree thrived in eastern North American forests for thousands of years. It comprised about 25% of the trees in the natural range. A large, fast-growing deciduous beech species, this tree was a boon to the local ecosystem. Native Americans used the wood for building, the nuts for food, and the bark for medicine. The nuts were also a staple food for early European settlers in North America. Put another way, the American chestnut tree was among the most significant forest trees throughout its range.  

Today, the American chestnut is all but extinct in the wild thanks to a blight accidentally introduced to America in the early 1900s. Cryphonectria parasitica is the name of the parasitic fungus that causes chestnut blight. It devastated the existing chestnut trees. Native to East Asia, it also devastated European chestnuts. Once introduced in the U.S., the fungus spread rapidly and caused significant tree loss. The fungus destroyed about four billion American chestnuts in the first half of the 20th century.

Protecting the American Chestnut

There’s no cure for chestnut blight, but there are several things you can do to manage the disease and protect chestnuts if you love the tree species. One is to plant resistant chestnut hybrids. These hybrids are developed by crossing American chestnut trees with Asian chestnut trees, which are more resistant to the fungus.

Something else you can do to help chestnut trees is to support the growing number of organizations working hard to restore the species to its former range. These organizations are breeding blight-resistant chestnut trees and planting them in forests throughout the eastern United States. These organizations include:

• American Chestnut Foundation
• American Chestnut Research & Restoration Project at SUNY ES
• American Chestnut Cooperators’ Foundation (ACCF)
• National Park Service (NPS)
• US Forest Service (USFS)

The organizations are making a difference. The American chestnut is slowly but surely returning to its native range. One of the highlights of the Tree Council’s 2023 Summer Workshop at Goddard Park was a chance to see years of work by the American Chestnut Foundation come to fruition. The summer workshops held by R.I. Tree, along with our annual Tree Stewards Course, are among our most popular tree care programs. Look for more information on these workshops in the spring.

Proven Tips on Managing Plant Diseases

Prevention is the best defense against plant diseases. Site preparation and plant selection are critical steps to prevent plant diseases. But diseases can occur despite our best efforts. Below are some tips for managing plant diseases:

1. Remove diseased plant parts to prevent spreading.
2. Water your plants properly.
3. Prune away dead or diseased branches to improve air circulation and reduce the amount of inoculum in the plant.
4. Apply fungicides according to the label directions to help control the disease.
5. Keep your tools clean. Disinfect your pruning shears and other tools. Use a solution of bleach and water after each use.
6. Be aware of the weather conditions. Some diseases are more likely to develop under certain weather conditions than other diseases. Then, take steps to prevent the disease’s development.
7. Contact RITree. Its experts can provide information on common plant diseases in your area and recommend strategies for managing them.

By following these tips, you can help to protect your plants from disease and enjoy it. The best approach is to use a combination of cultural practices and chemical or biological controls to manage diseases effectively. Remember, there’s no silver bullet for managing plant diseases.

Fall is incredible in New England. The leaves change from green to rich rusts, ruby reds, and glittering golds as summer gives way to fall. Many trees look their best at this time. The fall is a great time to prepare your trees for the ravages of winter. Giving your trees some TLC now before winter protects them from harsh winter weather and helps boost spring growth. Below are seven things you should do before winter sets in to help your trees continue to grow and thrive.

1.      Soil care 

Chances are good that the soil in your yard isn’t as rich as that in the forest. That’s because the forest’s fallen leaves and organic matter enhance the soil, enriching it with nutrients. But you can boost your soil’s richness by doing three things. Apply a slow-release fertilizer in the fall. Freshen up the mulch before the ground freezes. And reduce irrigation to avoid flooding the soil. Trees get a lot of moisture in the winter.

2.      Prune your trees

Pruning is a wise annual practice. Prune dead, diseased, and unsafe branches from your trees. This strategy not only protects you and your home. It also influences a tree’s structure and shape. Trim lifeless branches. Cut cracked, loose, and diseased-looking trees near the trunk. And call an arborist for help with trimming large branches. Trim branches without leaving stubs and leave wounds exposed so they can heal.

3.      Prepare for winter

Winter takes a toll on trees. So, you must prepare them in the fall for the winter’s snow, frost, ice, and cold temperatures. Start by Inspecting your trees for weak branches that may need added TLC to survive the winter. Cable and brace these limbs. Cabling and bracing trees support poor or weak branch unions and reduce the strain and stress damage from high winds, heavy ice, and snow build-up.

4.      Water your evergreens

Give your evergreens a healthy gulp of water before winter. They’ll be well-hydrated throughout the cold winter. Harsh winter weather can cause water loss in an evergreen’s needles and freeze its roots. Water regularly throughout the fall. You want to moisten the soil, not saturate it. Weekly deep root watering with slow soaking is an ideal tree care strategy. It’s an efficient way to get your tree the right amount of water.

5.      Inspect trees and shrubs

The fall is a good time to inspect your trees and shrubs. Look for pests and diseases that might have settled in. You don’t want them getting out of control. Conspicuous damage, early fall color, and other signs of stress could indicate a deeper underlying problem.

Start by identifying the disease or pest. Then, determine how to treat the pest or disease.

Identifying a pest or disease can be a challenge. So, if you’re unsure what the pest or disease is, consult a local arborist for help. Or, contact the Rhode Island Tree Council for help. They can provide a trained eye to help you identify the problem and suggest the best way of eliminating it. Consulting an expert saves you time and money.

6.      Look out for Root Decay

Pay attention to the mushrooms growing at the base of your trees. They may appear for only a few days at a time. Some mushrooms can eat at and decay a tree’s roots, creating an unstable tree. Prevention is the best way to eliminate root decay.

So, don’t over water your trees, encourage healthy mycorrhizal fungi by enhancing soil organic matter and avoiding soil compaction, and protect trees from damage by mowers, trimmers, and construction, which can kill roots and weaken trees.

Fall is an excellent time of year in New England. The change in color of the leaves is something to look forward to every year. Some think it’s the best season of all. Fall is also a time to prepare your trees for winter.

The cold, snow, and ice can damage them beyond repair, so you should have a plan to protect your trees before winter comes. The six steps we suggest you do above are a good place to start. Implementing them will not only protect your trees but also promote greater tree health come next spring.

John Campanini is the technical director of the Rhode Island Tree Council (RITree). A graduate of the University of Rhode Island, he was city forester for Providence for more than twenty years before retiring.

A highlight of the Tree Council’s 2023 Summer Workshop at Goddard Park was a chance to see years of work by the American Chestnut Foundation come to literal fruition.  Since the American Chestnut demise in the American landscape (A fungal blight has left the trees stunted), people concerned by the absence of this tree in our forests, have assembled a team, and concocted a scheme, whereby these wonderful chestnut trees may be rescued from a future of understory inadequacy.  Through breeding selection, resistance to this fungus has been sought. The project is looking fruitful. 

It is a wonderful story of science, passion, and hope.

Pursue the link below to see more.

Are you thinking of planting a tree? Fall is the best time to do that. It gives the tree plenty of time to root itself. A tree starts growing the second it’s planted. It will continue to grow as long as the soil temperature stays above 40°F (4°C). By the time spring comes, the tree will be established and growing.

Another reason to plant in the Fall is the soil. It’s a better fit for digging plant holes than in the Spring. Plus, the summer’s warmth still lingers in the soil. That keeps the soil moist enough for digging, making it perfect for planting.

Some people worry that winter will kill a tree planted in the Fall. No so. Trees go dormant in the winter so they can withstand the cold. In other words, they “hibernate,” like animals do in the winter. So, if you plant a sapling early enough in the Fall, it will have plenty of time to establish itself before the winter.

The tree will also have two growing seasons before the summer heat arrives and a healthy enough perception to survive. Ideally, you want to plant a tree at least six weeks before freezing temperatures arrive. Use October as a deadline for planting a tree.

Spring is also a Good Time to Plant

Spring is also a good time to plant a tree. But doing so then is risky. It might be too rainy for the soil to become stable enough for the tree to grow. That could prevent the tree from establishing itself enough before the summer heat arrives. Intense summer heat can kill a tree.

Spring, however, has one significant advantage over the Fall when planting a tree. Many local nurseries stock up on inventory in the Spring. So, you have more trees to choose from in the Spring than in the Fall. You may also have a better-quality tree to choose from in the Spring.

The time of the year you plant your tree, however, will only matter if you plant it in the right spot. Location is as critical as the time you plant it. Make sure you don’t plant the tree too close to existing structures. You’ll also want to research how much sun, wind, and water the tree prefers.

Knowing that information means you’re better able to pick a spot compatible with those conditions. And remember to call the free 811 Service to ensure there aren’t any underground utilities where you plant the tree. The tree’s roots could become a real problem for the utilities in time.

Finally, give your tree plenty of water—roughly one gallon of water per inch of diameter on the trunk. Mulch will help keep the tree moist and happy. Use up to 4″ and keep space between the trunk and the mulch. 

Crabapples: A Good Choice to Plant

Plenty of beautiful flowering trees are available when planting a tree. The Crabapple (Botanical name: Malus spp.) is an excellent choice if you are looking for a compact tree that brings year-round interest. Gorgeous spring buds, handsome summer foliage, and excellent fall color are among the Crabapple’s main draws. The Crabapple’s growth rate is moderate. It grows to about 15-20’, with a spread of about 15-20’.

The Crabapple blooms in mid-to-late Spring and features fragrant white, pink, magenta, or red blooms that typically last 1-2 weeks. Crabapple fruit ripens from late summer to mid-fall. Most cultivars have red fruit, but you can find yellow, maroon, and orange. Crabapples come in all shapes and sizes, including spreading, weeping, dwarf, vase-shaped, and columnar.  

The tree’s flowers bloom at slightly different times depending on the cultivar. One design consideration with Crabapples is whether to plant multiple types of Crabapples that bloom for a more extended period or plant the same type that provides an explosion of fragrance and color simultaneously.

A Crabapples’ fruit, however, is more than just ornamental. It also provides much-needed wildlife value, but its fruit is too sour to enjoy. The fruit comes in various sizes and colors depending on the cultivar. Some cultivars, such as the Malus ‘Guinevere,’ shown below, provide winter interest with the fruit.

If you’re thinking of planting a tree in the Fall, visit the RI Tree website at www.ritree.org to view small and medium-sized tree selections for residential landscapes. Or talk with a  member of RITree’s staff.

John Campanini

Technical Director, RI Tree Council

RI Tree recently announced that registration is now open for its fall Tree Stewards course, which will be held at the Barrington Public Library, 281 County Road, Barrington, RI 02806. The course’s lecture sessions will be held on September 7, 14, 21, and 28 from 6:30 p.m. to 8:00 p.m. The course’s planting session will be held on October 7^th from 10:00 a.m. to 12:00 a.m. Seating for the course is limited.

“The Tree Stewards course provides an in-depth look at the basics of tree care and growth and covers various tree-related topics,” says John Campanini, RITree’s technical director. “It’s always been our most popular course, so seating fills up quickly. It’s only one of RI Tree’s many activities in its efforts to educate the public about trees and their benefits.”

The Tree Stewards Course is held in the fall and the spring at locations throughout Rhode Island. The course reviews the basics of tree care and tree growth, including the following topics:

• Tree Biology
• Tree Identification
• Tree Health
• Planting & Pruning
• Urban Forestry
• Soil

The course also reviews insect and disease diagnosis, common invasives, and plant stressors. Attendees should bring a lunch to the Saturday workshops.

For more information about the courses or to register, call Robin Enos at RI Tree at 401-764-5885 or visit its website: www.ritree.org. People also can register by emailing the organization at ritree@ritree.org.

Stop Girdling from Squeezing the Life Out of Your Trees

Girdling roots is a more serious tree care problem than many think. Girdling is like wearing a belt about your waist that keeps getting tighter and tighter and tighter. It can strangle the life of a tree. Girdling occurs when a tree’s lateral roots at or just below the soil’s surface encircle or cut into a tree’s trunk, restricting the flow of water and nutrients and weakening the tree dramatically.

Girdling is as bad a problem in tree care as volcano mulching and poor pruning. It needs to be addressed as soon as possible. What causes it? The USDA-FS recently published a list of the major causes of girdling root problems.

At the top of the list is container-grown plants. When a tree stays in its container too long, its roots can become problematic. With nowhere else to go, they encircle the tree’s ball. If they aren’t loosened during planting, they can become girdling roots.

Below are additional causes for girdling:

• Soil obstructions (i.e., hard-pan)
• Improper root cutting (either during nursery harvesting or construction activities)
• Burial (too deep planting)
• Volcano mulching
• Berms and saucers (built too high or too low during plant installation)
• Multi-stem plants (too little room between stems for roots to grow)
• Nearby trees (competition from other roots and stems)

Leaving pieces of the planting container in the planting hole can lead to girdling roots. So, can planting a tree in heavily compacted soil and proximity to foundations, curbs, and other obstructions.

Fortunately, griddling is easy to spot. The most obvious sign is abnormal trunk flare. Instead of the tree trunk flaring where it meets the ground, it appears straight or narrower. Additional signs of girdling include roots circling the tree above the soil line and early leaf drop, as well as small leaves and canopy dieback.

Treating and Preventing Girdling

Digging the right-size planting hole is the best way to prevent girdling. Contrary to what many people think, digging the hole deeper isn’t necessarily better. In fact, it’s one of the worst things you can do when planting a tree. Digging a planting hole with a width of about twice the size of the root ball—no deeper than the root ball is ideal.

Additional steps you can take to prevent girdling include keeping the soil you put back below the root flare and mulch away from the tree’s trunk. Also, break up any roots encircling the root ball before planting the tree. Water the plant consistently initially and inspect the roots for defects occasionally.

Removing the girdling roots is an option. But talk with a certified arborist first before doing so. He or she can help you avoid cutting the tree’s main stem. In the severest cases, you may have to remove the tree. If you need help with what to do, RI Tree can help you find a certified arborist.

RI Tree is again hosting its free tree workshops—one of the organization’s most popular education sessions. We started these workshops a few years ago, and they have caught on with people. The two-hour workshops review the knowledge, skills, and equipment you need to conduct safe and rewarding interactions with trees, landscapes, and community forests. 

These workshops generate increased awareness and a better understanding of the beauty, benefits, and concerns associated with trees and a healthy canopy. The workshops also offer a chance to explore local trees and discuss critical tree issues. RI Tree staff conduct the sessions, which run from 1:00 pm to 3:00 pm. The locations and topics of information, explanation, and discussion are below. 

• Champion Tour (Westerly @ Wilcox Park) July 18th

Visiting some Champion Tree specimens, we will present the program’s history and the process of nominating, scoring, and calculating a Champion tree’s score. The Helen Walker Raleigh Tree Care Trust, managed by the Rhode Island Foundation, generously supports the Walker Raleigh Champion Tree Program with a special grant.

• Preservation of Forest (Powder Mill) July 25th

These visits to the urban fringe forest will discuss preservation strategies and forest health issues. 

• Reading the Landscape (Newport @ Morton Park) August 8th

This visit to Morton Park will focus on the efforts of sustaining canopy in an urban park. These discussions will also focus on how correct planting, large tree maintenance, and physical infrastructure plays a role in providing well-canopied recreational spaces.

• Preserving Elder Trees (E. Greenwich @ Goddard Park) August 15th

A park stroll looks at tree structure and its relationship to health, maintenance, and performance. How a tree is treated in its formative years determines the capacity and need for future maintenance. If you have developing or established landscapes, this session can help determine appropriate care.

• Tree & Ornamental Training (Johnston @ RITree) August 22nd

This session focuses on pruning practices and strategies for fruit trees and young nursery stock.

You can register for these workshops at the RI Tree website, which features some of the other events, programs, and workshops we offer, as well as our tree care videos and blog.

Proper Planting Techniques Boost a Tree’s Survival Chances

Thinning crowns. Stunted leaves. Dying branches. These signs indicate a tree’s slow and steady decline over the years. But even dead trees have stories to tell. A closer look at a dead tree’s trunk often tells you what caused the tree’s demise.  Healthy tree trunks have solid, continuous bark. Ding tree’s tree’s bark, on the other hand, is broken or has sections missing. it’s a sign that something is wrong.

Bark defects are instructive if you know how to interpret them. They tell you that the tree’s sapwood—its “plumbing”— has died. Sapwood contains millions of rectangular tube-like cells stacked one on top of the other. They feed nutrients and water to the tree. That, in turn, supplies the leaves, stems, and roots with the nourishment they need to survive.

When a plant’s sapwood fails, however, the channeling of these vital plant elements slows. Eventually, it stops. That isn’t good for the tree. Bark defects suggest the tree has suffered from malnutrition and water loss for years. While that information is helpful, it doesn’t explain the tree’s ultimate demise. So, what caused that?

The tree’s trunk or root flare tells you what happened. If there’s no flute-like shape at the flare, someone may have planted the tree too deeply, damaging the tree’s root system and stopping vital nutrients from getting to the tree. That, in turn, set in motion a series of events that weakened the tree’s primary functions and internal structure. Eventually, it leads to its death.

If whoever planted the tree had used the proper planting techniques, the tree might have lived a long time. In other words, the tree’s death was avoidable. Unfortunately, losing a tree because of improper planting techniques isn’t uncommon. That’s why you need to plant a tree using the correct techniques. That boosts its survival chances and ensures the tree gets all the nutrients it needs to survive and thrive.

See our section on tree care tips to learn how to plant a tree correctly and how to ensure it survives during the early stages of growth.

Spring is a great time of the year. With life emerging from its long winter sleep, it’s among nature’s most active seasons. But spring is also a time when plant pests emerge. These pests can ravage your trees and kill them. Basically, you can divide tree pests into three broad categories—sap-sucking insects, wood borers, and defoliators.

Pests invade trees when they’re under great stress. Pests introduced from outside their native range can severely impact crops and natural tree populations, generating billions of dollars of economic and ecological damage. However, what insects you’ll need to watch out for this summer depends on your location.

Tree pests cause tremendous to natural and managed land annually. Most tree damage is caused by 20-22 common insect pests. These pests can devastate a tree if left untreated and cause extensive economic damage by destroying landscape trees that has to be removed and replaced. The impacts of pests are often made worse by climate change, which may allow additional pest life cycles per annum.  

Not all pests are deadly, however. Some play critical roles in natural and managed systems, contributing to carbon cycling and forest regeneration. They may even contribute to shaping patterns of global tree diversity. Below are five pests to look out for and descriptions of telltale signs that they have invaded your trees:

1.      Arborvitae leafminer

If you see brown foliage now on your “Green Giant” and “Emerald Green” cultivars, it’s a sign that these pests are feeding on your plant’s leaves. This leafminer pest is a small caterpillar, green or brownish, with a dark head and a spot just behind its head. Mature caterpillars generally appear between April and June. While this pest likes all arborvitae varieties, they prefer American pyramidal, globe, and golden arborvitae.

2.      Cedar Rust

Cedar apple “rust” can affect the health and vigor of your apple trees by causing early defoliation and reducing fruit quality. They present as orange gelatinous spheres and indicate the presence of fungal spores from the Gymnosporangium family, which can later infect Malus species. Cedar rust is especially harmful to Junipers. Severe infections of this disease, which first appear on leaves as small greenish spots and then gradually enlarge and change color, can kill a tree.

3.      Holly Leafminer

As the name suggests, it feeds on English, American, and Japanese hollies. If you see tiny green blisters on a lower leaf’s surface, chances are good the female of this pest has laid eggs there. The Holly leafminer “causes the presence of yellow, brown, or reddish mines on the leaves. In the beginning, the mines are narrow and winding. But they then become large blotches as the larvae overwinter in the leaf. The upper and lower surfaces of leaves remain after feeding and are easily separated. Larvae are yellowish and about 1/16″ long. The adult is a small black fly.

4.      Boxwood Leafminer/Blight

These pests are among the most destructive—and deadly— of the boxwood insect pests. The larvae feed on the tissue between the leaves’ outer surfaces, producing blotch-shaped mines in the boxwood leaves. Circular leaf lesions are a crucial symptom of boxwood blight, as are leaf yellowing and leafminer injury blistering. Infested leaves appear blistered from late summer through the following spring. New leaves, however, don’t show signs of mining until deep into summer, when the larvae are larger. Premature leaf drops may result from heavy infestation by fall or early spring.

5.      Pine Needle Blight

A common fungal disease among pines, especially mugho and Japanese white pines, pine needle blight attacks pine needles, causing spots, blights, and premature defoliation. Initially, spots emerge in summer or late fall. It’s a group of diseases. Cyclaneusma needle cast symptoms appear as light green to yellow spots on infected 2-year-old or older pine needles. Dothistroma needle blight causes yellow to tan spots in the fall. Lophodermium needle cast appears in late fall to early spring. It presents as brown spots with yellow margins on young needles. Brown bands form later.  

These five pests are common in the Northeast. But don’t panic if you see one or more of them on a tree’s leaves or something foreign on its bark. Instead, get to work diagnosing the problem and deciding on the best treatment for the pest. Treatment for these pests, however, varies. So, if you need help treating them, contact the RI Tree Council as soon as possible. We’ll help you eliminate these pests and boost your tree’s health.

John Campanini is technical director of the Rhode Island Tree Council (RITree). A graduate of the University of Rhode Island, he was city forester for Providence for more than twenty years before retiring.