Wednesday, April 19, 2017

La Verne Resident Suffers from Redwood Blues

Q. I spoke with you about a week ago on the phone regarding some declining sequoia trees in La Verne. You were kind enough to offer your help by reviewing a few things. You  requested I send you pictures, watering information and treatment information. The pictures are attached and the watering and treatment information is below. The trees were planted in late 2008/early 2009.


The trees are watered 7.1 MIN 4 Start times 2 days a week the sprinkler is a spray head. It was changed out about 6 months ago to the sprayers. Previously it was bubblers.

The sequoias/redwoods trees were treated on 2/29/16, 3/25/16, 5/6/16, 5/27/16 and 7/1/16 and the service was suspended in August. Each service was a deep root injection with the following chemicals/fertilizers:

Companion 2-3-2 high rate
Essential plus 1-0-1 high rate
PH reducer high rate
Arbor care 15-8-4
Iron max 6%

A. From what I can see your redwoods are not doing badly; considering they are growing in an environment that is not conducive to their growth  (that is, anyplace that is not the central and northern California coastal region) . There are some problems however:

1.       Their skirts are hiked up. Redwoods, especially those growing in inland areas, prefer not to trimmed at all during their lifetimes. The‘skirts’ are those branches which hang down to the ground. They provide both a humid environment underneath the tree that allows for a more gradual shift in moisture of the root zone between irrigations and protection from bark chewing deer. They also prevent people from holding activities in the very sensitive root zone of the trees that could damage them.
2.       They’re suffering from compulsiveness. Redwoods prefer a deep layer of their own refuse (needles, bark etc.) that they produce over their lifetime. This thick layer of spongy organic material provides for an even more gradual drying out of the important ‘root zone’ soil underneath the trees. The redwood has particularly shallow roots so this, along with the protective skirt, creates a growing zone for the tree that is necessary for it to survive. Also, the breakdown product of this needle and bark layer is beneficial to those organisms in the soil that are beneficial to the tree. Removing the needles from the trees (or planting a lawn under them) can be a death sentence.

So what can you do?  Do not trim your redwoods. Also, until they can produce a layer of their own mulch, put down a six-inch-thick layer of small fir bark or gorilla hair fir bark in an area that represents their eventual canopies.
Start changing the water schedule gradually to once a week for 20-40 minutes (remember you changed from a bubbler (good) to sprinklers (not so good)).  Do not feed them, and remove either the lawn or the tree in it as redwoods and lawns are not compatible in your situation.  And of course, limit any traffic under the redwoods.

Feel free to contact me if you have any other questions.

Cheers,  Frank

Wednesday, April 12, 2017

Out and About at the Arboretum

Things are looking good. 
Canary Island exhibit. 

Asteriscus maritimus (Gold Coin Daisy)

Aloe section

Ceiba insignis

Around the peacock cafe

Thursday, April 6, 2017

Trees For L.A. 's Future

Since the massive irrigation systems here in Southern California were installed allowing people to plant almost anything with no thought to its environmental impact, many trees that normally would not grow here have been planted. This has lead to our current dilemma where these usually well watered trees are failing due to the massive drought we are  currently experiencing. What are the alternatives? What trees can we plant in the future that take into account the reality of our water resources? Here's a few: 

Crepe Myrtle (Lagerstroemia indica)

Even though this Taiwanese native is under attack from several new pests it is still a very hardy, non-thirsty, and colorful climate appropriate small flowering tree. 

Grevillea 'Moonlight'

Though classed as a shrub, this beautiful white flowering shrub can be trained as a small (15 foot) tree. 

Brachychiton rupestris

This hardy native of Australia is stays small (usually no larger than 30 feet) yet makes a big impression with its bottle shaped, water storing base. Not only is it a decent tree, it doubles as an architectural element. You can plant your very own stonehenge. 

Trumpet trees (Handroanthus sp.)

Native to South America, these reliable bloomers are moderate growers and, once established, easy on the water. 

Handroanthus impetiginosa (R), Handroanthus chrysotricha (L)

Handroanthus impetiginosa

Chinese Fringe Tree (Chionanthus retusus) 

These chinese native trees put on a spectacular display in the spring, and once established are easy on the water. 

Silk Floss trees (Ceiba sp.)

Native to South and Central America, these water savers reliably bloom just around world series time. They can get quite large so give them room and their propensity to shed large branches limits their use in areas where that might be a problem. The white species, Ceiba insignis, blooms more frequently than C. speciosa. 
Ceiba speciosa

Ceiba speciosa

White Ceiba insignis

Ceiba insignis lit up at night with a health light. 

 Desert Museum Palo Verde

This hardy Southwest native does well in inland valleys here; not so well in coastal areas. 

Callistemon viminalis

The weeping bottlebrush tree is vastly underappreciated. It's low water use and blooms for 2-3 months of the year. 

Arboretum senior biologist Jim Henrich admires a Callistemon viminalis.