Don’t fertilize with phosphate unless your soil actually needs it by Neil Hendrickson, PhD

Phosphorus in fertilizer (in its available form, phosphate) is derived primarily from mined rock, most of which comes from Morocco. In the days before routine soil nutrient analysis, arborists included phosphorus in standard NPK (nitrogen-phosphorus-potassium) tree and shrub fertilizers according to use in agriculture: farmers added “balanced” fertilizer to promote growth and replace elements lost to harvesting crops. The

trouble is that arborists do not harvest a crop, and so typically do not need the same elements in the same amounts.

Soil analyses frequently indicate that phosphorus is abundant in the soils over a large part of our service areas; consequently, the many regional blends of Bartlett BOOST®, based on hundreds of thousands of soil samples, do not include phosphorus. If soil tests indicate a phosphorus deficiency, it can easily be added as needed.

This prescription approach to phosphorus fertilization is beneficial for three key reasons:

77 First, phosphorus that does not get taken up and used by the plant can well end up in a body of water where it becomes a pollutant that can promote algal blooms and cause oxygen depletion; this is an international problem for streams, lakes and oceans

77 Second, excess phosphorus fertilization can lead to diminished availability of other nutrients

77 And last, the supply of easily accessible phosphate rock in the world is predicted to begin to diminish by the early 2030s, making it more expensive in the short term and more difficult to acquire in the longer term

It will make life easier if you find out that you don’t need phosphorus.

So “Don’t Guess, Soil Test!”—and don’t apply phosphorus unless soil test results indicate the need.

A customized approach to fertilizing is better for both

your trees and the environment.

TREE & SHRUB CARE FROM BARTLETT TREE EXPERTSTREE TIPS

TREE & SHRUB CARE FROM BARTLETT TREE EXPERTSTREE TIPS

Western cedar borer by Drew Zwart, PhD Over the past few years in the Pacific Northwest, Bartlett arborists have noted many

western red cedars and some related species—both in the forest and in hedge plantings—showing lower branch death, sometimes leading to tree mortality. Investigation of this problem has revealed the western cedar borer (Trachykele blondeli, a flathead borer) as the cause.

Swelling and gallery at attachment of a dead branch.

The damage begins when newly hatched larvae tunnel through lower branches, where the eggs were laid, and into the trunk at the point of branch attachment. Swelling of the branch collar and exit holes or frass in that area are typical signs of attack. These lower branches die, and in some cases the damage in the trunk girdles and kills the upper portion of the tree.

While known as a forest/timber pest for some time, the western cedar borer appears to be increasingly damaging in landscape settings.

Ask your Arborist Representative to inspect your trees and advise you on practices for prevention (and if needed, treatments) to manage this emerging problem.

Bartlett’s Kyle Offerdahl and Lyle Feilmeier with Nancy Herpers of the Portland Garden Club.

Each year the Bartlett Research Laboratories process the results from more than 15,000 soil samples submitted by Bartlett Arborist Representatives from client properties. Before any fertilization is performed, soil samples are taken from the property, analyzed in the lab, and recommendations

are written for clients by our laboratory scientists. The resulting soil care programs are some of the most intensive in the landscape industry.

Every soil, in every geographic location and property, is different. That means that fertilization for any location can be different. We offer more than 15 different blends of our own Boost® fertilizers as well as custom blends for each site, or even for individual plants.

Our scientists have developed and implemented a system of review and delivery of soil analysis reports to clients and Arborist Representatives. Those reports help us to make educated decisions about client property care and to obtain maximum results for our clients’ landscapes!

Soil sampling – we make informed recommendations

Fun with trees Turn a twig into a tree! To make this cheery springtime tree terrarium, you’ll need a glass canning jar, a small twig that fits in the jar, some colored tissue paper—and for assembly, craft glue and a small bit of modeling clay (or for older kids, a hot glue gun). Gather a few twigs in case one breaks in little hands. First make small balls of crinkled tissue and glue them onto your twig to create a spring tree. Next, stand your tree on the inside of the jar lid with the clay, and glue on some crinkled tissue for grass. Then carefully lower the jar over your tree, screw the jar shut and… Tada! You have a tree terrarium!

Renovating the Lilac Garden at Portland’s Duniway ParkArborist Kyle Offerdahl and the Clackamas office of Bartlett Tree Experts have been working with the Portland Garden Club and City of Portland botanists since 2015 to help renovate the overgrown Lilac Garden located in Duniway Park along Terwilliger Boulevard. Club members have been working tirelessly on this volunteer project—pruning, weeding, edging, mapping, identifying, planting new lilacs and adding underplantings—and Bartlett is honored to help them.

The Garden is surrounded by steep hillsides covered with fir and cedar, a wonderful backdrop for lilacs in bloom. Come see them this spring! There are

approximately 225 plants (more than 125 varieties): most are hybrids of Syringa vulgaris that bloom from late March through early May. Visit again in June to see a large Japanese tree lilac in bloom.

Read how in 1936 the Portland Garden Club donated the original lilacs to the city. www.theportlandgardenclub.org/community/lilac-garden

For most of the past 43 years, Dr. Bruce Fraedrich has been at the helm of the operations at the Bartlett Tree

Research Laboratories in Charlotte, North Carolina. And what a time it’s been! As vice president and chief scientist, he has helped to research and develop so many of the products and services you read about in this newsletter that it would take a page and a half to list them all.

Dr. Fraedrich has dedicated his career to advancing arboriculture and keeping Bartlett as the leader in our industry. It has been our privilege to work with him and to learn from his vast knowledge.

As a main contributor and editor of Tree Tips, Dr. Fraedrich distilled scientific information and made it accessible for our readers. His articles have always educated us and enabled us to more fully understand the complexities of tree and shrub care.

The International Society of Arboriculture gave Dr. Fraedrich its highest honor, the Award of Merit for “outstanding, meritorious service in advancing the principles, ideals, and practice of arboriculture.”

We wish Dr. Fraedrich all the best in his retirement.

Honoring Bruce Fraedrich, PhD

TREE FOCUS:Giant sequoia (Sequoiadendron giganteum)HistorySequoiadendron giganteum is the sole living species in the genus Sequoiadendron, and one of three species of coniferous trees known as redwoods. Giant sequoias are the world’s largest single trees, and are among the oldest living things on earth. They are found naturally only in scattered groves of the western Sierra Nevada mountains of California, mostly protected in national parks. After its discovery in the 1850s, the giant sequoia became popular in English estate gardens, which now hold the largest specimens outside the United States. Its wood is resistant to decay, but as trees mature, becomes too brittle for lumber.

Culture77 Grow well in cooler climates where winters are snowy

and summers are dry

77 Adapted to fire, with fire-resistant bark and cones which open once dried after exposure to fire

77 Prefer moist but well-drained sandy loams and full sun

77 Sensitive to temperature and moisture extremes

77 Can be difficult to transplant

Concerns77 Have no serious insect or disease problems;

however, trees planted outside their natural range are more susceptible

77 Slowly disappearing because of lack of fire and climate disruption

Bartlett Management Practices77 There are almost no management concerns,

except, because of its great potential size, to provide room for it to grow to maturity

77 Roots are particularly shallow, so protection from soil damage such as construction or gardening is critical

77 Pruning and fertilization are rarely necessary

77 Irrigation in landscape settings during drought is advisable

77 In national parks, prescribed fire and scarification of the seedbed might be necessary to help regenerate stands of giant sequoia

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© 2019 The F. A. Bartlett Tree Expert CompanyPNW1

The Rogerson Clematis Garden in West Linn, Oregon, is on the grounds around the historic Luscher Farmhouse. Winding paths lead through this unique residential setting to the various display areas. Known as “the Queen of Vines”, the clematis plant grows in a seemingly endless variety of sizes, shapes, forms and colors. This collection contains unique and exceptionally rare plants, as well as historic clematis and the newest hybrids.

The Rogerson Clematis Garden has 1,800 clematis! It is a local Bartlett favorite; many of our staff enjoy visiting, and Bartlett Division Manager Kevin Carr serves on the board of this non-profit garden.

The Garden is open to visitors every day from dawn to dusk, and the greenhouse is open on weekends (May–October). The paths are accessible to most people, including those with strollers, walkers or motorized chairs. Learn more at www.rogersonclematiscollection.org.

A beautiful place to visit this spring – Oregon’s Rogerson Clematis Garden

Compliments of

Ask your Arborist to check the health of your trees and shrubs.