The Drought Deepensby Drew Zwart, PhD

Most areas of California are entering the third straight year of extreme drought conditions, and many trees and shrubs are paying the price.

Early effects of drought include wilting or discoloration of foliage, shedding of leaves or needles, and reduction in growth. As drought stress continues, plants become more susceptible to disease and insect issues to which they would normally be resistant. Pests like borer beetles and canker fungi are often only found attacking stressed trees, and are being found more and more frequently affecting California landscapes.

Irrigating plants is the first approach, though not for Californians who are asked/mandated to cut back on water usage. Mulching the root zone with fresh wood chips will help to retain irrigation or natural moisture in the soil, and it will help to regulate extreme soil temperatures, which is an additional tree stress that often goes hand in hand with drought.

In addition, there are a few more advanced options that may become necessary as the drought continues:

Wetting Agents: One heavy watering with a wetting agent will allow future irrigation events to be more effective in moistening the root zone.

Plant growth regulators: Treated plants will have slightly smaller leaves, thicker leaves and thicker wax cuticles (an important water saving adaptation), hairier leaves, and more energy going to root growth.

Opportunity Grows on Trees by Alan Jones, VP, Division Manager

A primary Bartlett mission is to improve and continue advancements in the Tree Care Industry. One way we do that is through researching equipment and procedures at the Bartlett Tree Research Laboratories and making those discoveries available throughout the green industry. This is a practice that has always been a part of our identity as a company.

At the same time, The Bartlett Tree Foundation was also established to provide scholarships to promising students that have a genuine interest in pursuing a career in arboriculture/urban forestry. The Foundation has evolved over the years to include more and more colleges and universities and to provide additional opportunities via scholarships and supporting programs by providing workshops to students, teaching classes and serving on advisory boards. Ultimately, we hope that these opportunities lead those students to a career in the Tree Care Industry.

The Bartlett Tree Foundation ScholarshipsThe Bartlett Tree Foundation provides scholarship funds annually to participating two-year and four-year college programs. Bartlett has affiliations with some of the finest universities throughout the country.

The participating institutions, in accordance with their criteria, select the student recipients. The students must be actively enrolled in a course

The Bartlett Tree Foundation helps students working towards careers in the Tree Care Industry.

of study that leads to a degree in arboriculture, forestry, urban forestry, horticulture, plant pathology, botany, or other closely related discipline. Students must maintain a sufficient grade point average to be considered. Good character, noted recognition, and financial need are also determining factors for student eligibility. Students at participating schools can contact their professors for further information.

At-Large Scholarships for Any Schools That Offer Relevant ProgramsThe At-Large scholarship program allows the Bartlett Foundation to assist programs in horticulture, arboriculture, or urban forestry at two and four-year colleges and universities that are outside of our currently supported schools. The program also provides the opportunity for existing Foundation schools to assist additional deserving students in their academic pursuits. All of these scholarships are for students who have a genuine interest in a career in arboriculture.

We now have several Arborist Representatives who began as students and interns and who subsequently became employees who contribute to the continuing cycle and make more advancements to the Tree Care Industry possible.

For more about the Bartlett Tree Foundation and the scholarship program please visit www.bartletttreefoundation.org.

TREE TIPST R E E & S H R U B C A R E F R O M B A R T L E T T T R E E E X P E R T S

Continued on page 3

Drought killed these pines.

Oak scorch from drought.

Tree Focus-Velma’s Royal Delight Crapemyrtle by Greg Paige, Arboretum Curator

Importance of Diversity in the Urban Forest by Neil Hendrickson, PhD

Crapemyrtle is multi-stemmed tree that is quickly becoming more common in landscapes across the country. A true multiple season of interest plant, this genus is grown not only for its colorful, late blooming flowers but also for its showy bark and consistently beautiful fall color. The most common species is Lagerstroemia indica. Nurseries offer many cultivars and more are being developed all the time. There are sizes and shapes to fit any palette and flower colors from whites to reds, pink and purple and every shade in between.

Unfortunately, often little care is taken to select an appropriate cultivar for the site resulting in

the wrong plant for the spot. A worthy smaller cultivar that is a favorite of mine is Lagerstroemia indica ‘Velma’s Royal Delight’. This cultivar is well suited to our shrinking urban landscape since its very compact; usually reaching only four to five feet high with an equal spread.

The foliage is a nice dark green with good mildew resistance and decent fall color. The flowers are a very nice magenta often covering the plant. Its bark is not as showy as some cultivars but still offers good winter interest. It also has excellent cold hardiness. Velma’s Royal Delight is a very good crapemyrtle to add to the urban tree list.

Diversity in the urban landscape concerns arborists everywhere. We learned from the near-extinction of the American elm due to Dutch elm disease in the 20th century that over planting a single species can have catastrophic results. In a monoculture, it only takes one pest or disease to devastate an entire tree population.

It is now commonly suggested that no one species should represent more than 5% of an urban planting. This increased diversity is a challenge:

It will be hard to achieve the uniform look along streets that many find desirable

There’s no guarantee that a pest or disease with a broad host range will not do serious damage

A desirable variety of species might not be adequately available

Some species may not be as well adapted to a local urban environment as others

Our changing environment and/or global trade could introduce new and exotic pests.

More plant diversity doesn’t assure a problem-free urban forest future. However, it will also improve the biological diversity of insects and birds. And most important, more diversity will lead to the ultimate goal of urban forest sustainability.

Ivy on Trees by Drew Zwart, PhD

Although long used as a ground-cover and with a name synonymous with venerable old institutions; simply put, ivy is bad for trees.

No ivy species is native to the United States. Many species are aggressively invasive and displace native species. In North America, the most common culprits are English ivy (Hedera helix) and Irish or Atlantic ivy (Hedera hibernica).

Ivy is problem in landscape settings because it competes with desirable plant species for water and nutrients, but most importantly, ivy leads to concern for tree structure and failure potential.

For arborists the issues related to tree health and safety are the major concerns regarding ivy. Ivy can reduce tree stability and lead to failure for a number of reasons. Structural or flare roots are one of the most critical areas of a tree to inspect. If this area is obscured by ivy, no arborist can conduct a proper risk assessment of the tree, and critical information about tree stability cannot be determined. In addition, ivy adds considerable weight and wind resistance in a tree canopy. Since ivy is evergreen, the added weight of rain, snow, or ice will accumulate on ivy-covered trees in winter.

Mitigation: The best scenario for trees and the native environment is to eradicate ivy from the landscape. This can be achieved through hand removal, judicious use of herbicides, or ideally a combination of the two.

If complete removal is not desired from an aesthetic or budget perspective, there are a

few practices that can limit the negative impact of ivy on trees and the environment. First, remove ivy from tree

trunks, and pull ivy back at least 3 feet from the base of any tree. This will mitigate the weight, moisture, and wind resistance issues associated with ivy, and will leave the structural roots visible for inspection. In addition to tree trunks, whenever possible ivy should be prevented from climbing on any vertical surfaces such as walls or fences. Ivy only produces seed when it is growing vertically, so a well maintained groundcover of ivy is far less likely to provide seed for invasion of natural areas than ivy that is climbing up walls or trees.

Properly managed ivy may add aesthetic value to a landscape, however all too often this invasive weed is left to run amok, damaging ecosystems and leading to structural instability and unknown risk in large trees.

If you have a problem with ivy on your property contact your Bartlett Arborist.

Ivy should be kept back from the base of any tree.

Bartlett Supports Community Tree Planting by Patrick Franklin, Special Assistant to Bartlett’s President

Book ReviewsThe Olive in California: History of an Immigrant Tree by Judith Taylor, MD

The olive tree has been a symbol of peace, strength, and nourishment since its earliest cultivation in the ancient civilizations of the Mediterranean. From the first Spanish ships to touch California’s shores to the rise of a thriving industry with hundreds of olive growers and oil makers, this book traces the path of this sturdy, life-giving tree as it developed into a California agricultural phenomenon.

Arizona & New Mexico Getting Started Garden Guide: Grow the Best Flowers, Shrubs, Trees, Vines & Groundcoversby Mary Irish and Judith Phillips

The southwest is home to some of the most beautiful

landscapes and formations in the entire country. Alongside its famed attractions - the Grand Canyon, Rio Grande Gorge, and Havasu Falls among them - the region caters to a vast array of unique plant life, specially adapted to thrive in warm, dry climates as well as at high elevations.

Trees of Southeast Texas: A Guide to Common Native Species (Quick Reference Guides) Pamphletby Robert O’Brien

Trees are a key part of the habitat of a region and can give an area it’s unique character. This beautifully illustrated, waterproof pocket guide will help you get to know the most

important native species that make up the habitat of the Southeast Texas, Houston and surrounding areas. Over 250 stunning illustrations — leaf shapes, fruits, nuts, berries, flowers and tree shapes — depict 54 of the most common native trees and cover the basics of tree identification.

Drought (Continued from page 1)

At Bartlett, trees are more than just our business. We are committed to increasing tree planting and stewardship in our communities. That’s because we know that large scale participation is necessary for urban tree populations to thrive and grow – now and in the future.

With Bartlett’s seedling program, our Arborists personally distribute over 25,000 tree seedlings to students, community groups, local reforestation efforts and others. Our goal is not only to get these seedlings into the ground, but to

teach and inspire our communities (especially our youth) to care for trees – and to plant even more of them every year!

Additional goals and objectives that we have set out to accomplish with this program include:

Promote awareness among school children and the general public about the value of planting trees, and the benefits trees provide to people.

Help increase the urban green infrastructure.

Create additional habitats for wildlife.

Increase the local diversity of native tree populations to better withstand natural disasters such as insect and disease outbreaks.

Help local communities reverse the increasing deficit of urban and suburban trees lost through development.

Promote community tree planting and habitat restoration efforts.

Support local community re-planting projects after major storm events.

During 2014, our Bartlett Arborists distributed 37,150 tree seedlings throughout the U.S., Canada, England, and Ireland. So far in 2015, 26,145 trees have been donated to local communities, school groups, and Arbor Day / Earth Day events. That’s a total of 63,295 trees in the year and a half since we initiated the program! At this rate we expect to donate over 100,000 trees in three years. Although it will be a while before the cities and towns begin to experience the benefits these trees will provide as they grow larger, we feel confident that our Arborists are already making a difference in their local neighborhoods and communities.

Our Arborists personally distribute over 25,000 trees each year.

Potassium Phosphite: Research has shown that it increases plant tolerance to environmental stresses such as drought, and also improves resistance against some secondary stress-related disease issues.

Avoiding drought stress for woody plants requires multiple tactics. First, maintaining vigorous plants through proper maintenance and selecting appropriate plants for the growing conditions will limit the impact of water shortage. Second, proper irrigation rates, frequencies, and delivery method will help to reduce water losses to run-off, competition with turf, and evaporation. The third approach is to help maintain the soil moisture that is present by adding wood chip mulch. Finally, some of the more scientifically advanced approaches may become necessary as the drought continues.

Improve Pollination in an Orchard or GardenPoor pollination in an orchard or garden can be corrected by introducing bees. Mason Bee “Pro Bee Block” Homes are an easy solution. These bee houses provide pest protection, sanitation and time-savings. They’re economical and completely recyclable. Visit www.masonbeehomes.com to learn more.

TREE TIPS

LAB NOTES

Compliments of

Enjoy your landscape this summer! Keep it healthy and beautiful.

published by THE F. A. BARTLETT TREE EXPERT COMPANY(877) BARTLETT (877-227-8538) in U.S. and Canada • www.bartlett.com

For Tree Tips information contact smurdock@bartlett.com© 2015 The F. A. Bartlett Tree Expert CompanyW2

Arid Climate Root Invigoration by Thomas Smiley, PhD

Many non-native trees and shrubs struggle to survive in hot, arid regions. One reason is low levels of organic matter in the soil. Organic matter from plant leaves, bark and roots breaks down quickly in warm soil due to high microbial activity. This is unfortunate because organic matter is very important for holding soil moisture and providing nutrients.

One of the most effective ways to get more organic matter into the soil is with Root Invigoration. This is Bartlett’s patented process of tilling compacted soil and adding organic matter and nutrients in order to promote tree and shrub root development.

Root Invigoration uses high pressure air excavation tools to break up the soil and then to incorporate soil amendments. Since air is

used, there is typically very little damage to the root system of the tree.

One recent advancement with Root Invigoration is the introduction of Biochar, which can now be incorporated along with composted organic matter in the Root Invigoration process. This combination of Biochar and composted organic matter will increase the water and nutrient holding capacity of the soil.

Mulching over the top of the Root Invigorated soil reduces the soil temperature, reduces water evaporation, and provides a future source of organic matter.

Root Invigoration is one of the unique services that the Bartlett Tree Expert Company can provide in arid regions. Contact your Bartlett Arborist Representative if you would like to find out if your trees are suitable candidates for Root Invigoration.