- Author: Janet Hartin
Welcome to Fall!
It's my favorite season and likely for many of you, as well. Beyond the holidays and extra time with family and friends, nature radiates its beautiful hues. In addition to lovely foliage, deciduous trees often expose exquisitely shaped and sturdy trunks. And, of course, there is the lovely fall foliage showcased by many species.
Did you ever wonder why trees "turn" color in the fall? The short answer: It's primarily a function of long, cool fall nights and short, sunny days. The longer answer? Chlorophyll is responsible for the basic green color of leaves we see in spring and summer and is a necessary component of photosynthesis, which uses sunlight to manufacture sugar (food) that is stored during the dormant period of the year. Carotenoids produce yellow, orange and even brown pigments in crops such as carrots, squash, bananas and many ornamental plants such as daffodils and poppies. Anthocyanins are red and orange in color and are most linked to lavish displays of brilliant fall foliage. They also give rise to coloring of strawberries, plums and cherries.
Here's the kicker: While chlorophyll and carotenoids are present in leaf cell chloroplasts throughout the entire growing season, during fall chlorophyll begins to break down. Voila! The lovely yellow and orange hues we all look forward to seeing are finally exposed. In addition, red hues (called anthocyanins) are produced in fall. So, in reality foliage doesn't "turn" orange or red at all.
Interestingly, the actual timing of color change varies across species and appears to be genetically inherited. The same species will exhibit a similar color scheme in cool temperatures in higher elevations at nearly the same time as it does in warmer lower elevation climates.
The intensity of color can vary quite a bit however. Where do temperatures enter the picture? Both the amount of color and the overall intensity of fall color is very linked to weather conditions that occur prior to and during the actual time the chlorophyll in leaves winds down. The most brilliant displays occur after several warm, sunny days and cool, crisp (above freezing) nights. This is because although lots of sugars are made in leaves during sunny daytime hours, the corresponding cool nights prevent the sugars from moving out. The amount of soil moisture also helps ensure that from year to year fall colors vary even in the same trees. So, either a late spring or a prolonged drought can both delay the display of fall color by a few days or even a few weeks.
What's the recipe for the most brilliant fall display? Most likely a warm, moist spring followed by a warm summer and sunny fall with cool autumn nights. Although fall color is not nearly as spectacular in lower elevations of Southern California compared to other colder areas of the nation, the liquidambar or American sweet gum (Liquidambar styraciflua) offers some pretty impressive fall color and an impressive 300 to 400-year life span. (Did you know that liquidambar got its name because it at one time was a sought-after chewing gum for Native Americans?)
Two “climate-ready” tree species with lovely fall foliage that grow in both the west portion of the county and the desert are the ‘Keith Davey' Pistache, a large street and park tree sporting crimson to scarlet colored foliage and its relative, the ‘Red Push' Pistache, a hybrid between P. atlántica x P. integerrima) which has lovely red foliage as it emerges in Spring as well as Fall. Others include the Raywood Ash (Fraxinus oxycarpa 'Raywood') sporting a reddish-purple hue in the fall, and the ‘Sunburst' Locust (Gleditsia triacanthos var. inermis 'Sunburst') which offers a vivid display of fall color. Unfortunately, it is susceptible to the Invasive Shot-Hole Borer. If you have one of these lovely trees already, take good care of it to help it stand up to this aggressive pest!
Happy Fall! Enjoy the cooler weather, family and friends, and lovely trees!
- Author: Janet Hartin
Fall is a great time to plant trees in our urban landscapes. Temperatures are cooler than summer and trees adjust to transplanting much better than during the heat of summer.
Why trees? Trees reduce surface temperatures of asphalt and other dark impervious surfaces by over 60 degrees F in inland cities during spring and summer. They also reduce energy usage and costs, enhance habitat and pollinator populations, absorb and store carbon dioxide, provide oxygen for our subsistence, reduce erosion, reduce glare and noise, add beauty to our neighborhoods, and enhance mental and emotional health.
I am appreciative to UCCE San Bernardino County Master Gardener trainee Alex Shippee for his graphic design wizardry, making a drab publication on planting trees inviting and appealing to read.
Have more questions about your trees? Contact the UC Cooperative Extension Master Gardener tree helpline in San Bernardino County. 22trees4tomorrow@gmail.com or our general telephone helpline at (909)387-2182 or email mgsanbern@ucanr.edu where your gardening questions can also be addressed. (You will also reach this website by following the QR code link above.) We also have this handout available in Spanish.
- Author: Janet Hartin
Applications Now Being Accepted for the University of California Cooperative Extension Master Gardener Program “Trees for Tomorrow Start Today” Project.
University of California Cooperative Extension (UCCE) San Bernardino County is currently recruiting adults (18 and over) who are interested in becoming volunteers for our "Trees for Tomorrow" project. Complete training is provided online through a 50-hour Master Gardener training class taught by subject matter experts. Master Gardener volunteers will provide research-based information on the selection and care of heat, drought, and pest resistant trees and help our non-profit partners and community leaders enhance tree canopy cover in our most vulnerable neighborhoods. (To date, we are proud to have partnered with the Inland Empire Resource Conservation District, CA Climate Action Fellows and many non-profit organizations, communities, ESRI, and others to give away over 600 trees in the last year!)
Applications to become a UCCE Master Gardener volunteer for this project are open through August 31, 2022. UCCE Master Gardener “Trees for Tomorrow” Volunteer Application link: http://ucanr.edu/u.cfm?id=287
Questions about the application process or the volunteer opportunity? Contact UCCE Area Environmental Horticulturist Janet Hartin at jshartin@ucanr.edu
Why volunteer for this project? We are facing unprecedented times due to climate change and urban heat islands increasing temperatures in our communities. One of the solutions to a "cooler, greener, tomorrow" is through tree planting and proper selection and long-term care of heat, drought, and pest resistant trees.
Why trees? Shade produced by a single tree can reduce surface temperatures of asphalt and other impervious surfaces by up to 65 degrees F. Trees also lower air temperatures; enhance pollinator and wildlife habitat; absorb pollutants; reduce energy use and related costs (homes, offices, vehicles); beautify neighborhoods; absorb and store carbon dioxide; and provide many other ecosystem and societal benefits.
You can make a difference like never before enhancing tree canopy cover in our neighborhoods. Do you want to learn more about what UCCE Master Gardeners do for San Bernardino County residents and communities, find out what upcoming events they are hosting, or have them answer your horticulture questions Here's your pot of gold: https://mgsb.ucanr.edu/
We are looking forward to hearing from you!
- Author: Janet Hartin
University of California Cooperative Extension Drought Resources To Keep Your Plants Alive
"Trees Come First Under Drought and Water Restrictions"
Keeping Plants Alive Under Drought and Water Restrictions (English) https://anrcatalog.ucanr.edu/pdf/8553.pdf
Keeping Plants Alive Under Drought and Water Restrictions (Spanish) https://anrcatalog.ucanr.edu/pdf/8628.pdf
Prioritizing Trees During Drought and Water Restrictions (5 minute Youtube)
https://www.youtube.com/watch?v=CTKLlJgdLVk
Tips to Keep Your Landscape Trees Alive Under Drought https://ucanr.edu/b/~IjC
Landscape Tree Irrigation to Maximize Tree Health, Benefits, and Beauty https://ucanr.edu/b/~YjA
Landscape Tree Irrigation 101 https://ucanr.edu/b/~UjA
Top 10 Ways to Conserve Water in Your Landscape and Garden https://ucanr.edu/b/~tTD
Asphalt and Synthetic Turf are Superheating our Cities (in Desert Sun newspaper) https://www.desertsun.com/story/opinion/contributors/valley-voice/2022/04/09/coachella-valleys-asphalt-synthetic-lawn-heat-islands-reach-170/9515857002/
Use of Graywater in Urban Landscapes in California https://anrcatalog.ucanr.edu/pdf/8536.pdf
Need More Help? Speak to a UC Cooperative Extension Master Gardener in Your County of Residence. 
- Author: Janet Hartin
1. Select drought-resistant plants that grow well in your climate zone and microclimate (sun, shade, etc.). Try these search engines:
SelecTree: A Tree Selection Guide (calpoly.edu) Plant Search Database
Plant Search Database - Water Use Classification of Landscape Species (WUCOLS IV) (ucanr.edu)
For inland San Bernardino County: Home - Inland Valley Garden Planner
2. ‘Hydrozone': Place plants with similar water needs (very low, low, medium, high) together and water the hydrozones on different valves (or, if hand watering, water plants requiring the most water longer but not necessarily more often than other plants).
3. Make sure your irrigation system is operating properly (pressure, spacing, no weeds around heads, no broken parts, etc.).
4. Irrigate based on species and seasonal water needs (highest in summer) and soil type (sandy loam, clay loam, etc.).
5. Irrigate slightly below the current root zone depth of your plants to encourage deep rooting into cooler soil: - 6”-8” for annuals, perennials, and turf - 8”- 1' for shrubs - 1' or deeper for trees
6. Water early in the morning when soil evaporation is minimal.
7. Control weeds. They compete with your garden plants for water.
8. Spread and maintain 2-4” of mulch around garden plants and trees (3-4” for wood chips, 2” for pebbles, decomposed gravel, etc.) keeping it a few inches away from tree trunks.
9. Avoid over-fertilizing. Too much nitrogen creates weak growth and the need for more water.
10. If you have a lawn and still want to keep it, water based on the UC ANR 'Lawn Watering Guide': http://ucanr.org/freepubs/docs/8044.pdf
Contact a trained University of California Cooperative Extension (UCCE) Master Gardener in San Bernardino County for more help! mgsanbern@ucanr.edu (fastest!) or: (909)387-2182 (leave a message for a return phone call)
Redlands trees
