TREE & SHRUB CARE FROM BARTLETT TREE EXPERTSTREE & SHRUB CARE FROM BARTLETT TREE EXPERTSTREE TIPS

Phosphorus in fertilizer (in its available form, phosphate) comes primarily from mined rock, of which most 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

Always test before fertilizing with phosphate by Neil Hendrickson, PhD

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 two key reasons. 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. And second, 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 it.

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

Be aware of heat stressMost of us are

familiar with the results of drought

stress, but did you know that high temperatures alone can cause significant damage to the health of your plants? With many areas recording rising temperatures, we should know how warmer temperatures affect the physiology of plants. High temperatures reduce photosynthetic rates faster than they reduce respiration rates. The result is an imbalance because the carbohydrates produced by photosynthesis are used faster than they can be replaced! Higher temperatures increase the loss

of water through stomates in the leaves, and thereby increase demands on the root system to take up water to cool the tree via transpiration. (High temperatures are usually accompanied by low rainfall—adding insult to injury.) Cellular membranes also become unstable and result in ion leakage within the leaf cellular structure.

So how do plants cope with high temperatures? One way is through the formation of heat-shock proteins (HSPs). Found in humans and other animals as well, HSPs perform the same function in both

Continued on page 2

Imaginative and funny leaf creations A piece of paper, a few leaves, a glue stick and a marker are all you need to have a little fun with your child! Lay a leaf on a blank sheet of paper and let imagination take over; draw additions around the leaf to create all kinds of images. Save favorite ones by using a glue stick to fasten the leaf in place.

Fun with trees

Heat stress (Continued from page 1)

TREE & SHRUB MAINTENANCE CALENDAR

JUNEIrrigate deeply 1–2 times for mature trees, more often for shrubs

Monitor/Treat for scale insect crawlers

Release beneficial predators to control mites and aphids

Monitor citrus foliage and developing fruit for citrus thrips

JULYIrrigate deeply 1–2 times

Fortiphite treatments to mitigate drought stress

Release beneficial predators to control mites and aphids

Monitor for powdery mildew on susceptible species such as blue oak, London plane, and roses, and treat at first signs of infection

Inspect coast live oaks for signs of “foamy canker” and treat as warranted

AUGUSTIrrigate deeply 1–2 times

Monitor scale insects, aphids, spider mites

Apply third pine beetle treatment

animals and plants: maintain the integrity and function of proteins in high heat. HSPs form in response to rising temperatures and help to stabilize proteins to ensure cell functioning; they help to moderate metabolic reactions that would otherwise speed up and cause an imbalance of metabolites and acidification in cellular tissue. Calcium also plays a critical role in temperature stress adaptation by modulating enzyme activity and stabilizing membranes. There are physical adaptations as well, such as increasing leaf hairs and waxes,

Watch out for borer beetlesTrees in California are under increasing attack by many species of the ambrosia beetle. Invasive shot hole borers (ISHBs) are

decimating sycamores and other native and non-native trees around Los Angeles and San Diego.

There are 3,500 species of ambrosia beetle, a type of beetle that bores deeply into trees to grow fungi inside the tree. Many ambrosia beetles have specific symbiotic fungi that are unique to that species of beetle. Most prefer to attack weakened and dying trees. They locate a stressed tree by the alcohol released from the bark of the tree. The beetles bring their own “seeds”, fungal spores actually, to start “gardens”of fungus. The fungus garden that grows is food for the larvae.

The beetles eat their introduced fungi and do not actually eat sapwood or live tissue, making management more difficult. The fungi that the beetles introduce can range from being innocuous saprophytes to virulent pathogens that kill trees, as is the case with the ISHBs in southern California.

Keeping trees healthy through proper plant health care and adequate irrigation is a vital tool in preventing beetle infestation.

Consult your Bartlett Arborist Representative if you have noticed either of these risk factors in your landscape:

77 Bleeding cankers – These dark, wet splits in tree bark often release alcohol, attracting ambrosia beetles

77 Frass from borers entering a tree

changing leaf morphology to reduce light interception, and changing leaf orientation.

Preparing plants for heat stress consists of the horticultural basics: plant properly in high quality soil, manage soil fertility, and irrigate properly. Bartlett recommends soil sampling to assess soil nutrition (particularly calcium) and physical properties in order to create a custom fertilizer to optimize the soil environment and enhance plant health. Contact your Bartlett Arborist Representative to learn more.

Fine sawdust-like frass at base of a tree.

Frass protruding from bark at beetles’ entry points.

TREE FOCUS:Valley oak (Quercus lobata)

HistoryValley oak, also called California white oak, is native to California, and is most commonly found growing in deep valley soils with year-round soil moisture. Early settlers used the presence of valley oaks as an indicator of deep rich soil suitable for agriculture. At maturity, the valley oak is the largest oak species in North America.

Culture77 Performs best in deep soil with medium

to high organic matter and some source of summer water

77 Lower branches tend to become quite large and extended, while upper branches typically form an arching growth habit

Concerns77 Large branch failure due to over-extension

and internal decay is common

77 Susceptible to oak pit scale

77 Commonly infested with a harmless but eye-catching gall caused by cynipid wasps

77 Though not susceptible to sudden oak death, may be infected by other Phytophthora species in poorly drained wet soil

Bartlett Management Practices77 To reduce failure potential, frequent pruning to

reduce weight or subordinate extended branches 77 Root Invigoration® to help meet this tree’s need

for rich organic soils77 Accurately timed treatments for pit scale to

effectively target the juvenile crawler stage77 In marginal site locations, supplemental

fertilization and addition of organic matter

WONDERS OF NATURE A rainbow-colored tree!

The large, tropical tree Eucalyptus deglupta gets its common name, rainbow eucalyptus, from its amazing multi-colored bark. Every year patches of the tree’s outer bark are shed at different times, in vertical strips, revealing bright green new bark underneath. This bark changes color as it matures, so in addition to the fresh green bark, there are streaks of blue, purple, orange and maroon bark on the tree all at once!

This tree thrives in tropical forests that get lots of rain. The colors of the bark are not as intense when the rainbow eucalyptus grows outside its native range.

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© 2018 The F. A. Bartlett Tree Expert CompanyCA2

Quarryhill Botanical Garden in Glen Ellen is one of the most exotic and biologically diverse places in Sonoma Valley. Miraculously, this 25-acre botanical garden escaped major damage from the fires that ravaged the valley. Quarryhill is a wild Asian woodland, intentionally not manicured and featuring one of the largest collections of wild-sourced Asian

plants in the world. You’ll see magnolias, dogwoods, maples, birches, roses, lilies, rhododendrons, and many other

horticultural specimens around the paths and ponds. Plan your visit at www.quarryhillbg.org.

A peaceful place to visit

Compliments of

It’s so easy being green when you have plant healthcare.