A monthly e-newsletter from UMass Extension for landscapers, arborists, and other Green Industry professionals, including monthly tips for home gardeners.
To read individual sections of the message, click on the section headings below to expand the content:
Hot Topics
Spring Kickoff for Landscapers: UMass Extension's Landscape Education Day
When: Tuesday, March 29, 2022 - 8:30am to 12:15pm
Wednesday, March 30, 2022 - 8:30am to 12:15pm
Where: Online
Sustainable landscaping uses multiple management strategies that seek to reduce negative impacts on the environment while maintaining aesthetically pleasing landscapes. Join us via GoToWebinar to learn management strategies and practices that you can implement to provide beautiful, functional and environmentally friendly landscapes for your customers. Attendees can choose to attend either of these half-day sessions, or both days.
Click here for full agenda and registration.
Pesticide credit:
For Tues. March 29, 2 pesticide contact hours for categories 29, 36, Dealers, and Applicators License.
For Wed. March 30, 2 pesticide contact hours for categories 37, Dealers, and Applicators License.
Association credits: 1 MCH, 1 MCA, and 1 MCLP available for each day. ISA credit requested.
Management of Eastern White Pine (Pinus strobus) in the Landscape: What does the future hold?
April 5, 2022, 6:30 - 7:30 pm, virtually via Zoom
Eastern white pines (Pinus strobus; EWP) have been suffering from serious health issues for over a decade now. Most importantly, changes in our regional climate have facilitated severe outbreaks of needle blight diseases. As one of the most common and largest tree species in our urban and suburban landscapes, direct management of EWP pathogens and insect pests may be necessary to maintain tree health.
This webinar will summarize the latest research findings from the USDA NE1601 working group that is focused on EWP health throughout its natural range. The group comprises University researchers, state and federal forest health professionals and management foresters. The underlying causes of EWP health issues will be reviewed along with cultural and chemical management options for trees in urban and suburban settings. 1 pesticide contact hour for categories 36 and Applicator's License.
Pesticide credit: 1 pesticide contact hour for categories 35, 36, 48, and Applicators License requested.
Association credits: 1 MCH, 1 MCA, and 1 MCLP available. ISA, SAF, and CFE credits requested.
To register, go to https://ag.umass.edu/landscape/events/management-of-eastern-white-pine-pinus-strobus-in-landscape-what-does-future-hold
Featured Plant
Salix discolor and S. caprea, Pussy willow
A harbinger of spring, pussy willow catkins have long been a popular cut stem to bring indoors to help celebrate the arrival of warmer days ahead. The “furry” catkins provide the common name, given to multiple Salix species including S. discolor and S. caprea. Male plants should be selected when planting for the fuzzy winter catkins.
Salix discolor, a native to North American, is most commonly found as a large multi-stemmed shrub (6-15’ tall) but can be a small tree (up to 30’). Leaves are lanceolate, up to 5” long, and a dull medium green. Fall color is a greenish yellow. Female plants have small greenish catkins whereas male plants have the fuzzy, gray catkins (1-1.5” long) prior to leaf emergence that the plants are known for.
Salix caprea is a fast-growing, short-lived deciduous, multi-stemmed large shrub or small tree native to Europe and Asia. It grows to 12-25’ tall and 8 -15’ wide with an upright habit and an almost oval outline. Stems are yellowish brown to dark brown in color. Leaves are alternate, 2 to 4 inches long, lanceolate, dark green above and gray-hairy beneath. Pussy willows are dioecious (male and female catkins appear on separate plants). Male plants produce a showy display of fuzzy, grayish catkins (1-2 inches long) in March (late winter). Female plants produce smaller greenish catkins. Salix caprea ‘Pendula’ is a weeping form, often grafted on a standard.
Salix discolor and S. caprea are hardy in USDA zones 4-8. They grow best in medium to wet soil in full to part shade, preferring full sun. They do better in drier soils than other Salix species, but are intolerant of dry soil. Pussy willows make a good addition to rain gardens and low wet areas. Rejuvenation pruning every 3-5 years helps to maintain a smaller shrub with better form. Both species are susceptible to several insect and disease problems. Aphids, scale, borers, lacebugs and caterpillars are potential insect pests. Potential diseases include blights, powdery mildew, leaf spots and cankers. Wood is weak and branches may be damaged by ice and snow.
Pussy willow is the featured plant for March in the 2022 UMass Garden Calendar.
Geoffrey Njue, UMass Extension Sustainable Landscapes Specialist
Trouble Maker of the Month
Springtime Preparation for Common Diseases of Landscape Trees and Shrubs
Late winter is a good time to think about preventative treatments for a variety of landscape tree and shrub diseases. Dormant season management can reduce or eliminate the overwintering inoculum source that initiates infections on new growth in the spring. In addition, cold temperatures prevent most pathogens from growing, limiting the risk of spread at this time. Pervasive and damaging diseases like fire blight, fungal stem and branch cankering, black knot of Prunus, and foliar anthracnose are examples where preventative care can make a difference in successful management.
Fire Blight: The bacterium Erwinia amylovora is responsible for fire blight. While the potential host range for this pathogen spans many rosaceous trees and shrubs, apple and pear are the primary landscape hosts. Preventative management should focus on the removal of dead branches and last season’s fruit. Branches, stems and fruit diseased by E. amylovora will often (but not always) appear black in color (as if blackened by fire, hence the name). Fire blight infections mostly occur in May when trees are in bloom. However, after the damage takes place, opportunistic cankering pathogens (described below) can often establish on diseased tissues, furthering the dieback. For proper identification of fire blight, samples should be collected early in the growing season. Pruning and removal of blighted stems and fruit when temperatures are below 40o F is ideal. Remove approximately eight inches of the branch away from the transition zone between diseased and healthy tissue (if possible) or remove the entire branch at the collar.
Stem Cankering/Blight: Numerous fungal pathogens that are widespread in the environment are responsible for stem cankering diseases on landscape trees and shrubs. A few of the most prominent and destructive include Botryosphaeria s.l., Phomopsis, Cytospora and Nectria. These fungi can overwinter within active cankers on live branches and on dead material lingering in the canopy. Again, when temperatures are below 40º F, these fungi will be dormant and there is little risk of spread. Removing infected and dead parts substantially reduces the overwintering inoculum these fungi use to produce infective spores when temperatures warm. Newly flushed shoots and leaves are highly susceptible to infection in the spring season before the protective bark is fully formed. Just as with fire blight, prune several inches away from the transition zone between diseased and healthy tissue to ensure removal of the pathogen. If trees and shrubs with persistent stem cankering infections are growing near lawns that receive overhead irrigation, redirect the spray away from these plants. While the supplemental water is helpful during prolonged dry periods, irrigation that regularly wets the canopy provides the necessary moisture required by cankering pathogens to initiate new infections and readily spread throughout the canopy once established. If drought stress is a threat, drip irrigation or soaker hoses should be utilized instead.
Black Knot: The fungal pathogen Apiosporina morbosa is responsible for black knot. All species in genus Prunus are susceptible, but cherry and plum typically suffer from the worst infections in this region. The dormant season is the best time to scout for black knot before the cankers and galls become concealed by foliage. The early stages of black knot can be difficult to identify without very careful scouting. The cankers appear as circular to oval-shaped swellings on small diameter stems. These cankers may quickly girdle infected stems or the stems remain alive and perennial cankers develop. When perennial cankers are present in the canopy, the symptoms appear as enlarged, splitting/cracking, black-colored galls. The galls are a mixture of fungal and host tissue and these infected stems and branches can persist for many years. However, when the disease is widespread throughout the canopy, decline is inevitable. The pathogen thrives on trees in shaded settings, so ensure that cherries and plums receive full sun. Prune out interior canopy stems and branches that are heavily shaded, ensuring that all branches are receiving ample direct sunlight. Removing interior canopy stems and branches will also improve air flow, limiting the time that moisture persists. Black knot can co-occur with brown rot (caused by Monilinia spp.). Once the two pathogens become established, it’s very challenging to maintain a tree with any aesthetic value or sufficient fruit production. Prune infected branches with knots or one-year-old stems with evidence of cankering (discolored or sunken bark, oozing sap) at least four inches away from visible symptoms. This sanitation pruning can coincide with structural pruning to improve light and air flow. Dispose of the debris off site to ensure the pathogen doesn’t sporulate from stems and branches piled nearby.
Foliar Diseases of Deciduous Hardwoods: Late winter and early spring interventions aid in the management of leaf spot diseases such as apple scab, black spot on rose, tubakia leaf blotch of oak, tar spot of Norway maple, and foliar anthracnose diseases. Foliar disease fungi overwinter in discarded leaves nearby or by lingering in the canopy. Some of these pathogens also overwinter underneath bud scales or within dead stems. Reduce immediate sources of inoculum by removal of leaves on the ground around susceptible trees and shrubs. A fall and spring removal may be required, especially when trees are in beds with dense shrubs or groundcover plants. While this action may not render the tree free of the disease, it does remove the most immediate source of infection and can significantly reduce the overall buildup of the disease as the season progresses.
Rhizosphaera needle cast: The fungal pathogen Rhizosphaera kalkhoffii is primarily responsible for infections on spruce in the landscape. In the northeast, Colorado blue spruce (Picea pungens) and white spruce (P. glauca) are most susceptible to severe disease, while Norway spruce (P. abies), Oriental spruce (P. orientalis) and Serbian spruce (P. omorika) are more resistant. Drought stress increases susceptibility to needle cast, along with other common landscape stresses. There are several other species of Rhizosphaera that attack true fir (Abies), true cedar (Cedrus), pine (Pinus), hemlock (Tsuga) and Douglas-fir (Pseudotsuga). However, on these hosts the disease is typically of little concern. Infections are initiated on newly emerging needles that remain wet for roughly 48 hours at temperatures near 75o F. However, the spores can survive for several weeks on dry needles until conditions become optimal. Most infections are initiated during late spring but autumn is another important time for infection. Scout trees for symptoms of infection, especially in the lower canopy. Specifically, purple to brown-colored needles, premature needle shedding and interior branch dieback. Severely diseased trees may have only the current year’s foliage. Remove lower canopy branches that are badly diseased to reduce inoculum and improve airflow. Mulching over discarded needles under the tree will also reduce inoculum by preventing spore production and dispersal from dead foliage. Preventative fungicide applications as new growth is emerging may help to slow disease progression. However, in most cases, the best case scenario will be to maintain the tree’s current appearance. Provide supplemental irrigation during extended dry periods.
Nick Brazee, UMass Extension Plant Pathologist
Q&A
Q. Which vegetables might be appropriate to grow in my fairly shady yard?
A. Virtually all vegetable crops perform best in full sun, i.e., a minimum of 6 hours of direct daylight. However, all is not lost with a less than ideal site. In areas receiving at least 2 to 4 hours of sun, you should be successful with crops such as leafy greens and scallions, as well as parsley, chives, and basil. If the yard gets only dappled sunlight, consider such selections as endive, leeks, leaf lettuce, spinach, radishes, turnip greens, and small-headed cabbage varieties.
Another option may be container gardening in any sunny patch of yard, patio, deck, or doorstep you have. Seed catalogs abound with compact varieties of just about any vegetable you might wish to grow. There are even container varieties of sweet corn on the market. Containers appropriate for growing vegetables are limited only by the need for drainage holes and non-toxic composition, and by your imagination. Use a soil mix designed for containers, or create your own by combining screened compost with coarse sand and coir fiber. It’s best to avoid using unamended garden soil in containers because of its tendency to compact; packed soil hinders drainage and aeration, which results in poor plant growth. Container vegetables will need a bit more attention than garden-grown vegetables. Regular watering, sometimes twice daily, is critical to prevent pots from drying out. A slow-release, natural fertilizer incorporated into the potting mix prior to planting will buffer against nutrient loss from frequent watering.
Q. Is there a rule of thumb for which vegetables to direct seed into the garden and which to start indoors for transplanting?
A. Whether you transplant versus direct sow a particular crop can depend on a variety of factors, including the plant’s growth rate, how well the plant tolerates root disturbance after germination, and your particular preferences and site conditions.
Direct seeding works well for fast-growing, cool-season crops such as spinach and lettuce, and is recommended for vegetables that are grown for their roots such as carrots, radishes, beets, and turnips and crops that generally don’t tolerate the disturbance caused by transplanting such as peas and beans. Direct seeding is also the common method for establishing sweet corn.
Starting (or purchasing) transplants of warm-season crops with a long growing season is effective for our northern climate. Crops such as tomatoes, peppers, eggplants, pumpkins, melons, cucumbers, and squash benefit from an early start indoors with ideal temperature, light, and moisture conditions; conversely, direct sowing in cold garden soil exposes warm-season seeds to potential rot prior to germination and slow growth as well as pressures from weeds and diseases if seedlings do emerge.
Many plants can be handled either way, depending on your site conditions and harvest intentions. While direct seeding works for a range of vegetables, including lettuce, broccoli, cauliflower, cabbage, chard, and kale, using transplants of these varieties can result in an earlier harvest for succession cropping, or provide more reliable use of limited garden space.
Q. I’ve had issues with seedlings damping off in the past. What can I do to manage the problem this year?
A. Damping off, a general term for seedling decline, is commonly caused by fungal and mold pathogens, such as Rhizoctonia spp., Fusarium spp., and Pythium spp., which attack seedlings in the early stages of their development. These pathogens thrive in cool, wet conditions. Symptoms of damping off can include the wilting or sudden collapse of a seedling, a thinning or constriction of the seedling stem as well as stem discoloration at the soil line, and fuzzy white growth on infected plant parts. Damping off can spread rapidly throughout a seedling tray.
Give your seedlings the best chance to avoid the problem by adhering to these practices:
- Wash with soapy water any previously used seed starting containers, then wipe or spray them with hydrogen peroxide.
- Use a sterile seed-starting mix.
- Avoid crowding seeds when sowing, and thin out crowded seedlings.
- Guard against overwatering and excessive humidity: use containers with drainage holes, avoid standing water under containers, let soil surface dry somewhat between waterings, and remove plastic covers from trays after germination to reduce humidity.
- Transplant seedlings carefully, handling them by the leaves, not by their fragile stems.
- Maintain adequate air flow, warmth, and light around seedlings.
- At the first sign of damping off infection, discard the infected seedlings with their container to prevent spread.
Jennifer Kujawski, Horticulturist
Garden Clippings Tips of the Month
Feburary/March are the months to . . . .
- Be prepared. Supply chain issues are likely to continue and result in costly delays and labor inefficiencies. Plan ahead as much as possible to secure supplies, materials, parts and plant material.
- Brush up on the newest plants and cultivars. Take the time to check out various plant trials from universities, botanic gardens, and arboretums. These resources can help identify the top performing plants for the landscape.
- Fix and maintain equipment. Take the time now to work on tools and equipment. Fix broken handles, sharpen shovels and hoes. Make sure equipment with wheels are greased and tires hold air. Pruning tools like hand pruners, loopers and saws should be sharpened and oiled.
- Structurally prune. The lack of foliage makes it easy to observe tree structure and make structural pruning cuts. The ideal structure for most (not all) trees is a central leader with a system of scaffold branches that are larger in the lower portion and progressively get smaller toward the top. Scaffold branches should be well spaced vertically and horizontally around the trunk. Remove leader competition in the top of the tree. Remove or reduce branches that are larger than half the diameter of the trunk.
- Prune (some) shrubs. Shrubs like blueberry, elderberry, spirea, viburnum and winterberry should be pruned by removing a couple of the oldest stems near the ground. This will help maintain vigor in the shrub and promote new young vigorous growth from the bottom. For shrubs that don’t readily produce new shoots from the base, use removal and thinning cuts to open the canopy and promote sunlight penetration. The practice of removing no more than one third of the canopy is a good rule to reduce weakening the plant or promoting excessive regrowth. Wait to prune spring flowering shrubs that bloom on old wood except for selective pruning until after they flower.
- Take a couple woody stems inside to force. Crabapple, flowering quince, forsythia, magnolia, pussy willow and serviceberry are all fairly easy to force indoors.
- Avoid compaction. Late winter and early spring are times when soils are often saturated and therefore susceptible to soil compaction. Compaction destroys soil properties and may result in poor drainage, poor water infiltration, impediment of root growth and can cause anaerobic conditions. Compaction is difficult to fix, so prevention is the best option. Utilize sheets of plywood to help distribute weight when moving heavy materials or equipment over wet soils. For areas with frequent traffic over a long period, consider using a coarse mulch such as arborist chips 8” deep. Don’t forget even foot traffic and light equipment can compact wet soils.
- Start transplants indoors. March is a good time to start many annual vegetables and ornamentals inside. Use a sterilized seed starting mix to start seeds. Start seeds in small trays or pots and transplant into larger pots as they grow. When using supplemental light, set lights on a timer for 12-16 hours and keep the lights close to the foliage (about 6 inches). Vegetable transplants to start in March include spring brassicas (broccoli, cauliflower, cabbage, kale, etc), swiss chard, lettuce, and other cool season crops. Ornamental annuals to start in March include ageratum, celosia, coleus, impatiens, and petunias.
- Beware of ticks. Black-legged tick (deer tick) adults will be active any time the temperatures are above freezing. Keep yourself protected by wearing permethrin treated clothing and doing vigilant tick checks when done working outside for the day.
- Fix damaged turf. The end of March is a good time to fix damaged turf before the grass starts to grow. Fix areas that were damaged by snow removal equipment. Use a landscape rake or leaf rake to fix areas damaged by voles and moles. A vigorous raking is helpful to remove turfgrass foliage that has become matted or damaged by snow molds.
Russ Norton, Agriculture & Horticulture Extension Educator, Cape Cod Cooperative Extension
Street Trees and Pedestrian Safety: An Exploratory Study
Despite a growing body of research reporting the benefits of street trees, important knowledge gaps remain about their impact on pedestrians. How are street trees perceived as residents age? Do characteristics such as gender, socioeconomic status, or neighborhood impact how trees are viewed? Overall, how do trees make people “feel”?
Our recently published study in Urban Forestry & Urban Greening investigated the relationship between pedestrian perceptions of safety and the presence of street trees in several mid-sized U.S. cities. In this research, we explored the role of street tree density and preferences relative to pedestrian safety perceptions. This summary presents background information on the role of street tree plantings in transportation planning campaigns, especially in mid-sized post-industrial cities. Then, we outline our approach to the study and, lastly, report the findings. We close this article by briefly discussing major highlights.
Background
U.S. transportation planning as a tree planting partner
Increases of vehicular and pedestrian traffic in many urban areas have propelled the need to improve roadway safety conditions for motorists, pedestrians, bicyclists, and other transit users. Over the past several decades, transportation planners have discouraged street tree plantings from city public rights-of-way, out of concern that distracted motorists would be more likely to hit trees. However, researchers and practitioners now contend that these assumptions are based on rural and suburban roadways, and that urban streets have a different impact on driving behavior (Marshall, Coppola, and Golombek 2018). In other words, vehicle drivers in mixed-use city streets are likely to respond more positively to street trees and drive at slower speeds, whereas the opposite has shown to be true on rural roadways. Combined with many other livability benefits, trees are critical components of urban street design (Massengale and Dover 2014).
For example, in the United States, Complete Street policies and designs reallocate the entire right-of-way to people walking, biking, driving, riding transit, and moving actively with assistive devices (Smart Growth America 2021a). This approach often narrows the vehicle traffic lanes to accommodate multiple lanes of transportation and prioritizes slower traffic speed, which ultimately increases safety for anyone using the road. As of June 2021, Complete Streets policies have been adopted by 35 state governments, the Commonwealth of Puerto Rico, and the District of Columbia (Smart Growth America 2021b). Uniquely, the Massachusetts Department of Transportation is providing technical assistance and construction funding to municipalities with a Complete Streets policy and prioritization plan. Adding street trees as a performance standard in a Complete Streets policy is encouraged and grant applications that are doing so receive extra points (MassDOT 2016).
A similar long-standing program run by the U.S. Department of Transportation - Safe Routes to School - supports infrastructure improvements for school-aged children. Safe Routes to School design standards also promote the use of street trees to help narrow the roadway and encourage slower driving speeds. This creates more appealing walking and cycling environments, and it is believed to create a buffer between pedestrians and roadway traffic while discouraging other dangerous driving behavior (Safe Routes to School n.d.).
Additionally, the National Association of City Transportation Officials (U.S.) incorporates green infrastructure into street reconstruction guidelines. As part of their Urban Street Stormwater Guidelines (NACTO 2013), the strategic installation of green stormwater infrastructure - including street trees - is promoted to capitalize on benefits such as stormwater runoff interception and reduction of flooding, as well as shade for walking.
Complexities in “legacy” cities
“Legacy” cities of the United States are often designated as historic hubs of business and manufacturing that, in a post-industrial era, have experienced job loss, depopulation, and shrinking resources as a result of a decreasing tax base (Mallach and Brachman 2013). When compared to other mid-sized U.S. municipalities, legacy cities tend to face unique challenges: fewer adults with college degrees, higher rates of racial segregation and income inequality, and worsened public health outcomes (Berube 2019).
In turn, pedestrian perceptions of safety can also be impacted by neighborhood socioeconomic conditions. Over-policing, higher rates of fatal crashes in black and brown neighborhoods (MilNeil 2021), concerns for gender-based harassment, and insecurities based on immigration status (McDonald 2019) have been cited as chronic issues on many U.S. city streets. And those who experience public spaces from a disadvantaged position are not often incorporated into the decision-making processes that inform street redesign campaigns (Thomas 2020); thus, their concerns for personal safety may not be fully acknowledged.
Related programmatic challenges have also surfaced in tree planting campaigns in U.S. legacy cities. In Detroit, Michigan, about 25% of residents that were offered a free tree submitted a “no-tree request”; those residents who lived in the city through its recent economic decline took charge of outdoor stewardship when the city did not, and they assumed the same thing would happen again (Carmichael and McDonough 2019). Another case in Holyoke, Massachusetts revealed that, following a major tree planting initiative, the local municipal public works department was intended to be the primary caretaker of the new trees; however, the department was unable or unwilling to do so because of a lack of funding and misaligned program goals (Breger et al. 2019). Since street trees need to remain alive and survive in order to provision ecosystem services, this can be challenging for small legacy cities, whose underlying management capacity may be limited.
Approach
We designed a field study with the above-mentioned complexities of city streets in mind. The purpose of the research was to investigate the ways in which street tree density and preferences for street trees influence pedestrian safety perceptions.
Pedestrians from several western Massachusetts (U.S.) post-industrial cities were surveyed from neighborhood streets with a mix of commercial and residential buildings, and different street tree densities. Our participant pool was representative of post-industrial cities in the United States and Massachusetts, characterized by below-average annual household income, educational attainment, and capital asset ownership such as homes and cars (Commonwealth of Massachusetts 2016). The Cities of Chicopee, Holyoke, and Springfield were chosen due to high proportions of environmental justice neighborhoods, commitments to transportation safety and improvements, and proactive green infrastructure planning (Figure 1). For example, each city is registered with the Massachusetts Department of Transportation’s Complete Streets Funding Program, and two of three cities (Holyoke, Springfield) have approved municipal policies and prioritization plans that expedite Complete Streets implementation (MassDOT 2021). Additionally, each city takes part in the state-funded Greening the Gateway Cities initiative and, in community open space plans, has also indicated that street trees and urban forestry are essential components of green infrastructure.
Participants were asked to take a survey and rank a series of questions relating what they felt to be safe and unsafe about each street; this included features of the built environment such as crosswalks and sidewalks, features of the social environment including crime and crowding, and features of individual perception such as visibility and comfort. Participants were also asked to expand on what they appreciated about each street, then they were shown several images of streets with and without trees in the same neighborhood (Figure 2). The images also prompted participants to rank how much they liked the street shown and how safe they felt on those streets.
Prospective participants were recruited from three different types of streets in each city, including those with: (i) sparse amounts of street trees, (ii) abundant mature street trees, and (iii) new tree plantings. Using the Google Street View user interface and ground-truthed field visits, a length of approximately two city blocks was chosen as the unit of analysis after evaluating the streets of interest. To control for extraneous factors, study areas had approximately the same traffic volume, speed limit, sidewalk width, shoulder width, mixed-use land areas, and socioeconomic composition.
To isolate the impact of street trees on pedestrian perceptions of safety, we primarily looked to see if participant survey responses on streets with sparse amounts of street trees were different from responses on streets with mature street trees or new tree plantings.
Findings
Pedestrian concerns and indifference towards streets and trees
There are several ways in which street trees can reduce pedestrian perceptions of safety on a street. Previous research suggests that low, dense vegetation can obscure pedestrian lines of sight to nearby traffic or criminal assailants (Hur and Nasar 2014); on the other hand, too many mature street trees may increase opportunities for concealed street criminals (Fisher and Nasar 1992)). Additionally, the aesthetic value or comfort provided on a street may be devalued by pest invasion, hazardous tree limbs, damage from storm events, or pollution produced by tree care (Roman et al. 2020)
In our study, we largely found that perceptions of safety were modest or low regardless of street trees, averaging around 3 when ranked on a scale from 1 (very unsafe) to 5 (very safe), although the more a street was liked (aka preferred) a participant felt significantly safer (p< 0.001). Importantly, perceptions of safety did not statistically significantly improve on streets with trees, for neither mature trees nor new plantings (p=0.19). As alluded to earlier, there may be a range of socioeconomic and landscape variables beyond trees and the built environment that impact pedestrian perceptions of safety.
From the open-ended responses, only a few participants connected street trees with pedestrian safety, citing both positive (n=7) and negative (n=5) implications. Street trees could provide a barrier between traffic or inclement weather, e.g., “Bigger [create greater] obstacles for cars… safer for pedestrians to hide behind in case a car [is] out of control,” and street trees help to “escape from weather.” But, reduced visibility was the leading negative perception of street trees and safety (n=4). These insights are illustrated in Figure 3, showing how street trees–if not properly selected and managed–can impact pedestrian line of sight.
In spite of these concerns, we also found that neighborhood residents experienced fewer ‘concerns for safe walking conditions’ while on streets with mature trees compared to sparse trees (p= 0.04). Survey responses about ‘concerns for safe walking conditions’ included fear of crime, crowding, and traffic speed. Since many of our participants do not own a car and use local study area streets everyday, this finding could indicate important differences between pedestrians that live in an area versus those that commute into an area on a regular basis.
Pedestrian perceptions of safety
Pedestrians are afforded many benefits from street trees, including shade and pleasant aesthetics (Lovasi et al. 2013), improved conditions for physical activity (Lovasi et al. 2012), and contact with nature (Hartig et al. 2014). As reported by the American Society of Landscape Architecture (2018), such benefits elevate street trees as a health and safety intervention that can not only benefit pedestrians, but also roadway drivers and the surrounding environment.
As reported, when we first assessed the survey responses about ‘safe walking conditions’, organized by elements of clear sightlines, safe crossings, and streetscape amenities, we found that the amount of street trees did not significantly reduce pedestrian perceptions of safety across sociodemographic groups. An exception was found relating to household size; pedestrians living in houses with more people felt significantly safer on streets with mature street trees than on streets with fewer or newly planted trees (p<0.01).
Survey results also showed that older-aged pedestrians (p=0.03) felt significantly safer on any street - regardless of the presence or absence of street trees - when compared to younger pedestrians. This was a counter-intuitive finding, but our small sample size limited further investigation. Nonetheless, this is an important consideration when planning and designing for aging communities, which has been described as a mega-trend for the 21st century (Postone et al. 2019).
Regardless of street conditions, a clear majority relayed positive feelings toward trees. As seen in past research, beauty and aesthetic appearance were the most valued attribute of street trees followed by shading/cooling and providing a net positive for environmental protection. Studies about the values attributed to urban trees have found similar findings in New Haven, Connecticut (Locke, Roman, and Murphy-Dunning 2015), Porto, Portugal (Graça et al. 2018), Sapporo, Japan (Todorova, Asakawa, and Aikoh 2004), and beyond.
Conclusion
Incorporating tree planting into city redevelopment projects is often encouraged and incentivized (US EPA 2015). In light of increasing demand for safer streets as well as growing interest in urban greening via tree planting initiatives (Eisenman et al. 2021), our research team developed a field study to better understand how street trees affect pedestrian perceptions of safety in several mid-sized U.S. cities. Our primary conclusions are as followed:
- Perceptions of safety were modest or low regardless of street trees, which was surprising considering that many of our participants do not own a car and use local study area streets everyday.
- But, older-aged pedestrians felt significantly safer on any street - regardless of the presence or absence of street trees - when compared to younger pedestrians.
- Residents experienced fewer ‘concerns for safe walking conditions’ while on streets with mature trees compared to sparse trees, perhaps showing differences between those who live in an area versus those who commute regularly.
- While streetscape preference and perceived safety did not significantly vary across streets with mature tree density, new tree plantings, or sparse tree density, respondents identified street trees as an important element to walking through open-ended responses.
Literature Cited
ASLA (American Society of Landscape Architects). 2018. “Transportation: Street.” https://www.asla.org/ContentDetail.aspx?id=53815.
Berube, Alan. 2019. “Small and Midsized Legacy Communities: Trends, Assets, and Principles for Action.” Brookings (blog). November 13, 2019. https://www.brookings.edu/research/small-and-midsized-legacy-communities-trends-assets-and-principles-for-action/.
Breger, Benjamin S., Theodore S. Eisenman, Madison E. Kremer, Lara A. Roman, Deborah G. Martin, and John Rogan. 2019. “Urban Tree Survival and Stewardship in a State-Managed Planting Initiative: A Case Study in Holyoke, Massachusetts.” Urban Forestry & Urban Greening 43: 126382. https://doi.org/10.1016/j.ufug.2019.126382.
Carmichael, Christine E., and Maureen H. McDonough. 2019. “Community Stories: Explaining Resistance to Street Tree-Planting Programs in Detroit, Michigan, USA.” Society & Natural Resources 32 (5): 588–605. https://doi.org/10.1080/08941920.2018.1550229.
Commonwealth of Massachusetts. 2016. “General Laws, Part 1, Title II, Chapter 23A, Section 3A.” The 190th General Court of the Commonwealth of Massachusetts. https://malegislature.gov/Laws/GeneralLaws/PartI/TitleII/Chapter23A/Section3A.
Eisenman, Theodore S., Tamsin Flanders, Richard W. Harper, Richard J. Hauer, and Katherine Lieberknecht. 2021. “Traits of a Bloom in Urban Greening: A Nationwide Survey of U.S. Urban Tree Planting Initiatives (TPIs).” Urban Forestry & Urban Greening, February, 127006. https://doi.org/10.1016/j.ufug.2021.127006.
Fisher, Bonnie S., and Jack L. Nasar. 1992. “Fear of Crime in Relation to Three Exterior Site Features: Prospect, Refuge, and Escape.” Environment and Behavior 24 (1): 35–65. https://doi.org/10.1177/0013916592241002.
Hartig, Terry, Richard Mitchell, Sjerp de Vries, and Howard Frumkin. 2014. “Nature and Health.” Annual Review of Public Health 35 (1): 207–28. https://doi.org/10.1146/annurev-publhealth-032013-182443.
Hur, Misun, and Jack L. Nasar. 2014. “Physical Upkeep, Perceived Upkeep, Fear of Crime and Neighborhood Satisfaction.” Journal of Environmental Psychology 38 (June): 186–94. https://doi.org/10.1016/j.jenvp.2014.02.001.
Locke, Dexter H., Lara A. Roman, and Colleen Murphy-Dunning. 2015. “Why Opt-in to a Planting Program? Long-Term Residents Value Street Tree Aesthetics.” Arboriculture & Urban Forestry 41 (6): 324–33.
Lovasi, Gina S., Michael D.M. Bader, James Quinn, Kathryn Neckerman, Christopher Weiss, and Andrew Rundle. 2012. “Body Mass Index, Safety Hazards, and Neighborhood Attractiveness.” American Journal of Preventive Medicine 43 (4): 378–84. https://doi.org/10.1016/j.amepre.2012.06.018.
Lovasi, Gina S., Ofira Schwartz-Soicher, Kathryn M. Neckerman, Kevin Konty, Bonnie Kerker, James Quinn, and Andrew Rundle. 2013. “Aesthetic Amenities and Safety Hazards Associated with Walking and Bicycling for Transportation in New York City.” Annals of Behavioral Medicine 45 (S1): 76–85. https://doi.org/10.1007/s12160-012-9416-z.
Mallach and Brachman. 2013. “Regenerating America’s Legacy Cities”. http://bibpurl.oclc.org/web/81053, http:/ti.org/pdfs/LegacyCities.pdf.
Marshall, Wesley E., Nicholas Coppola, and Yaneev Golombek. 2018. “Urban Clear Zones, Street Trees, and Road Safety.” Research in Transportation Business & Management, Special Issue title: [RE]EVALUATING HOW WE VALUE TRANSPORTATION, 29 (December): 136–43. https://doi.org/10.1016/j.rtbm.2018.09.003.
MassDOT (Massachusetts Department of Transportation). 2016. “Complete Streets funding program guidance”. https://www.mass.gov/doc/complete-streets-funding-program-guidance/download
MassDOT (Massachusetts Department of Transportation). 2021. “Massachusetts Complete Streets Funding Program Participation”. Massachusetts Complete Streets Funding Program Participation
Massengale, John, and Victor Dover. 2014. Street Design: The Secret to Great Cities and Towns. John Wiley & Sons.
McDonald, Terrence T. 2019. “Bike Lanes Aren’t Just a White Thing.” Shelterforce (blog). December 9, 2019. https://shelterforce.org/2019/12/09/how-do-we-truly-make-streets-safer-for-everyone/.
MilNeil, Christian. 2021. “Data Confirm That More Fatal Crashes Happen in Commonwealth’s Black Neighborhoods.” StreetsBlogMASS. 2021. https://mass.streetsblog.org/2021/01/12/data-confirm-that-more-fatal-crashes-happen-in-commonwealths-black-neighborhoods/.
NACTO, (National Association of City Transportation Officials). 2013. Urban Street Design Guide. Washington, D.C.: Island Press.
Roman, Lara A., Tenley M. Conway, Theodore S. Eisenman, Andrew K. Koeser, Camilo Ordóñez Barona, Dexter H. Locke, G. Darrel Jenerette, Johan Östberg, and Jess Vogt. 2020. “Beyond ‘Trees Are Good’: Disservices, Management Costs, and Tradeoffs in Urban Forestry.” Ambio, October. https://doi.org/10.1007/s13280-020-01396-8.
Safe Routes to School. 2018. “Slowing Down Traffic”. http://guide.saferoutesinfo.org/engineering/slowing_down_traffic.cfm/
Smart Growth America. 2021a. “What are Complete Streets?”. https://smartgrowthamerica.org/program/national-complete-streets-coalition/publications/what-are-complete-streets/
Smart Growth America. 2021b. “Policy Inventory”. https://smartgrowthamerica.org/program/national-complete-streets-coalition/publications/policy-development/policy-atlas/
Thomas, Destiny. 2020. “‘Safe Streets’ Are Not Safe for Black Lives.” City Lab. 2020. https://www.bloomberg.com/news/articles/2020-06-08/-safe-streets-are-not-safe-for-black-lives.
Todorova, Assenna, Shoichiro Asakawa, and Tetsuya Aikoh. 2004. “Preferences for and Attitudes towards Street Flowers and Trees in Sapporo, Japan.” Landscape and Urban Planning 69 (4): 403–16. https://doi.org/10.1016/j.landurbplan.2003.11.001.
US EPA (Environmental Protection Agency). 2015. Green Infrastructure Opportunities that Arise During Municipal Operations.
Richard W. Harper, Extension Associate Professor of Urban & Community Forestry, UMass Amherst, Alicia F. Coleman and Theodore S. Eisenman, Department of Landscape Architecture and Regional Planning, UMass Amherst
Upcoming Events
For more details and registration options for any of these events, go to the UMass Extension Landscape, Nursery, and Urban Forestry Program Upcoming Events Page.
- Invasive Plant Certification Program - live via Zoom
- Mar 10, 2022 - State Regulations Pertaining to Invasive Plant Management (A2)
Two pesticide contact hours in categories 29, 36, 37, 40, 48, and Applicator's License. - Mar 17, 2022 - Principles and Fundamentals of Weed Science (A1)
Four pesticide contact hours in categories 29, 36, 37, 40, 48, and Applicator's License. - Mar 24, 2022 - The Invasive Plant Issue and Invasive Plant Identification (A3)
Three pesticide contact hours in categories 29, 36, 37, 40, 48, and Applicator's License. - Apr 7, 2022 - Developing an Invasive Plant Management Program (B)
Four pesticide contact hours in categories 29, 36, 37, 40, 48, and Applicator's License.
- Mar 10, 2022 - State Regulations Pertaining to Invasive Plant Management (A2)
- Mar 29 & 30, 2022 Spring Kickoff for Landscapers: UMass Extension's Landscape Education Day. For Tues March 29, 2 pesticide contact hours in categories 29,36, Dealers and Applicator's License. For March 30, 2 pesticide contact hours for categories 37, Dealers and Applicator's License.
- Apr 5, 2022 Management of Eastern White Pine (Pinus strobus) in the Landscape: What does the future hold? live via Zoom, 6:30-7:30 pm
One pesticide contact hour in categories 35, 46, 48, and Applicator's License requested
Pesticide Exam Preparation and Recertification Courses
These workshops are currently being offered online. Contact Natalia Clifton at nclifton@umass.edu or go to https://www.umass.edu/pested for more info.
InsectXaminer!
Episodes so far featuring gypsy moth, lily leaf beetle, euonymus caterpillar, imported willow leaf beetle, and spotted lanternfly can be found at: https://ag.umass.edu/landscape/education-events/insectxaminer
TickTalk with TickReport Webinars
To view recordings of past webinars in this series, go to: https://ag.umass.edu/landscape/education-events/ticktalk-with-tickreport-webinars
Additional Resources
For detailed reports on growing conditions and pest activity – Check out the Landscape Message
For professional turf managers - Check out our Turf Management Updates
For commercial growers of greenhouse crops and flowers - Check out the New England Greenhouse Update website
For home gardeners and garden retailers - Check out our home lawn and garden resources.
Diagnostic Services
Landscape and Turf Problem Diagnostics - The UMass Plant Diagnostic Lab is accepting plant disease, insect pest and invasive plant/weed samples . By mail is preferred, but clients who would like to hand-deliver samples may do so by leaving them in the bin marked "Diagnostic Lab Samples" near the back door of French Hall. The lab serves commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. See our website for instructions on sample submission and for a sample submission form at https://ag.umass.edu/services/plant-diagnostics-laboratory. Mail delivery services and staffing have been altered due to the pandemic, so please allow for some additional time for samples to arrive at the lab and undergo the diagnostic process.
Soil and Plant Nutrient Testing - The lab is accepting orders for Routine Soil Analysis (including optional Organic Matter, Soluble Salts, and Nitrate testing), Particle Size Analysis, Pre-Sidedress Nitrate (PSNT), and Soilless Media (no other types of soil analyses available at this time). Testing services are available to all. Send orders via USPS, UPS, FedEx or other private carrier (hand delivered orders cannot be accepted at this time). Please plan for the fact that date of receipt in the lab is affected by weekends, holidays, shipping time, and time for UMass Campus Mail to deliver samples to the lab. The lab provides test results and recommendations that lead to the wise and economical use of soils and soil amendments. For updates and order forms, visit the UMass Soil and Plant Nutrient Testing Laboratory web site.
Tick Testing - The UMass Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing options at: https://ag.umass.edu/resources/tick-testing-resources.
