A healthy approach to garden pest management

For as long as human beings have been cultivating crops and growing ornamental plants, pest control has been an important to-do. Anyone who grows plants for food or pleasure must also be concerned with the organisms that might harm those plants.

The word “pest” in garden lingo is fairly all encompassing. It can refer to animal species that consume and damage plants or spread plant diseases—gophers, rats, and other mammals; insects such as aphids, caterpillars, mealybugs, and mites; or other critters such as snails, slugs, and nematodes. It can refer to weeds or parasitic plants—bindweed, dandelions, mistletoe, spurge, and more. Or, it can refer to fungi, bacteria, and viruses—living organisms that are neither plant nor animal—some of which can harm plants.

Over the centuries, conventional wisdom about how to successfully manage plant pest problems has evolved. I recently stumbled across these two fascinating turn-of-the-century tidbits from an 1879 Illinois newspaper, advice we’re unlikely to follow today:

“For lice upon plants, syringe with a solution of soap and whale oil.”
“Very weak lime water will kill worms in flower pots.”

Successful pest control is a delicate balance. On the one hand, it’s important to manage plant pests so that they don’t do excessive harm. On the other hand, it’s critical to use the most effective and least toxic pest control approach to avoid serious environmental damage and human health concerns.

Integrated Pest Management (IPM) is the modern standard for pest control, based upon many decades of scientific research. It’s defined as “an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties.”

There are several key components to a successful IPM program:

  • Rule 1: Identify the pest. Just as you shouldn’t take a medicine without first diagnosing an illness, so you shouldn’t take any action before knowing precisely what your pest problem is. Inaccurate diagnosis can lead to an ineffective or even detrimental treatment program. If you’re uncertain of what pest you’re dealing with, use the services of our local Master Gardener hotline at (209) 953-6112 or the San Joaquin County Agricultural Commissioner at (209) 953-6000.
  • Rule 2: Choose the right control method. Very often, pest problems can be solved by using one or a combination of simple, non-toxic measures, without resorting to the use of chemicals. (More about this below.)
  • Rule 3: Evaluate the control and develop a pest management plan. This common sense and business-like approach means you should monitor all pest control methods to check their effectiveness, and then formulate an approach for the future.

Plant pest problems can often be easily prevented or minimized. Select plant species or cultivars that are disease-resistant and well adapted to the growing conditions in a particular space. Practice proper garden sanitation by cleaning tools regularly and disposing of diseased plant material properly. Water, prune, and fertilize plants in the right way at the right time to avoid stressing them and compromising their natural self-defenses.

Pest control methods can be grouped into several categories:

  • Cultural Control. This means changing plant care activities to reduce pest problems. For example, crop rotation helps minimize pest problems in edible gardens and agricultural plots. Also, landscapes with diverse plantings are less susceptible to pest problems than monocultures.
  • Mechanical Control. This simply means using some kind of physical action. Some examples: using a strong stream of water to spray off aphids or scale insects; hand-pulling weeds; using non-chemical traps; hand-picking caterpillars and snails; and using screens, barriers, netting, or mulches to exclude animals, insects, and weeds.
  • Environmental Control. Water, sun exposure, and soil conditions can affect plant health. For example, overwatering can lead to fungal infection and other plant diseases. Soil solarization can reduce weed germination and soil pathogens.
  • Biological Control. There are many species of beneficial insects (aphids, lacewings, predatory wasps, soldier beetles, and more) that work to reduce populations of harmful insects. Allow them to do their job, encourage them to stay by adding their favorite plants to your garden, and remember that pesticides often kill the “helpful bugs” along with the bad ones.
  • Chemical Control. Always use pesticides and herbicides as a last resort, and be sure to follow the application instructions to the letter, because overuse of garden chemicals has many serious, detrimental consequences. (Look up “Ten Reasons Not to Use Pesticides” by the Center for Environmental Health.) One very important thing to remember when using chemicals is that more is NOT better! Pesticide labels are legally binding documents; it’s illegal and dangerous to apply garden chemicals in a manner inconsistent with the instructions.

A screenshot from the UC IPM (Integrated Pest Management) website, showing the categories of available pest resources.
















The University of California IPM website is an excellent, detailed, and comprehensive resource for use by home gardeners, agricultural personnel, or natural resource specialists. Click on “What Is IPM?” for a reader-friendly explanation, or explore the website’s many pest-specific pages. You can also refer to the “Safe and Sustainable Pest Management” chapter of the California Master Gardener Handbook; it’s available through both the Stockton-San Joaquin County Public Library system and the Lodi Public Library.

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website.

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Special fall plant sales and garden events

Fall is a wonderful time to “think garden.” The peak heat of summer is over, garden events abound, and it’s a perfect time to plant. The late fall months (October and November) are especially ideal for re-landscaping or planting a new garden. Cooler daytime temperature means that plants experience less transplanting shock, while warm soil and rain showers encourage the growth of new roots before the cold of winter makes plants go dormant.

Take advantage of these upcoming events to buy special new plants, view gorgeous gardens, learn something new, or simply get outside in a beautiful setting:


Fair Oaks Horticulture Center Open Garden

When:      Saturday, September 8 from 9 a.m. to noon
Where:     11549 Fair Oaks Boulevard, Fair Oaks
Website:   http://sacmg.ucanr.edu/?calitem=389780&g=21788

This horticulture center—which celebrates its 20th anniversary this year—is the demonstration garden for the UCCE Master Gardeners of Sacramento County. It’s divided into several different areas: a water-efficient landscape, a composting area, an irrigation display, and an edible garden with fruit trees, vegetables, herbs, and more. During this free-to-the-public celebration, Master Gardeners will present mini-demonstrations on various topics at 10 a.m.

Fall visitors in the large edible garden at the Fair Oaks Horticulture Center. (Kathy Ikeda)


CNPS Fall Native Plant Sale (Sacramento)

When:      Saturday and Sunday, September 22 and 23 from 10 a.m. to 3 p.m.
Where:     Shepard Garden and Arts Center at McKinley Park
                3300 McKinley Blvd., Sacramento
Website:   https://bit.ly/2C7xIzT

This annual sale by the Sacramento Valley Chapter of the California Native Plant Society (CNPS) features a wide variety of California native perennials, shrubs, and trees. A bonus is the artisan market with creations by local artists. Admission is free, and if you join CNPS or renew your membership at the sale you will receive a complimentary one-gallon plant. Proceeds from this event support CNPS’s educational and conservation work.


Gardening with California Native Plants

When:      Tuesday, September 25 from 10:30 a.m. to noon
Where:     Robert J. Cabral Agricultural Center
                2101 E. Earhart Ave., Stockton
Website:   http://sjmastergardeners.ucanr.edu/?calitem=423404&g=3626

A free educational seminar by the UCCE San Joaquin Master Gardeners. Learn about the benefits of growing California natives, their cultural needs, and more. To reserve a space and class materials, call (209) 953-6100. While you’re there, visit the beautiful demonstration garden!


UCD Arboretum Plant Sales

When:      Saturday, September 29 from 9 a.m. to 11 a.m. (members only)
                September 29 from 11 a.m. to 1 p.m. (public sale)
                Saturday, October 13 from 9 a.m. to 1 p.m. (public sale)
                Saturday, November 3 from9 a.m. to 1 p.m. (public clearance sale)
Where:     UC Davis Arboretum Teaching Nursery
                Garrod Drive (across from the Veterinary School), UCD campus, Davis
Website:   https://arboretum.ucdavis.edu/plant-sales

These sales are extremely popular, so arrive early for the best selection! Enjoy choosing from the many special California natives and other plants at this one-acre nursery, including those on the Arboretum All-Stars list. You’ll be inspired by the water-wise landscaping, and can get guidance from the many gardening experts on site. If you have extra time, plan to wander the nearby Arboretum pathways and the Mary Wattis Brown Garden of California Native Plants.


CNPS Fall Native Plant Sale (North San Joaquin Valley)

When:      Saturday, October 20 from 9 a.m. to 1 p.m. (tentative)
Where:     Hughson Arboretum and Gardens
                Corner of Whitmore and Euclid Roads, Hughson
Website:   https://nsj.cnps.org

This annual sale by the North San Joaquin Valley Chapter of CNPS is held in cooperation with the Hughson Arboretum, whose mission is “to plant, maintain and make available to the public, native tree and plant species, trees of historic value, or other types of plant material to promote education about and appreciation of our natural environment….” The sale date is still tentative, so be sure to check the website for updates and confirmation.


Growing Fabulous Citrus

When:      Tuesday, October 23 from 10:30 a.m. to noon
Where:     Robert J. Cabral Agricultural Center
                2101 E. Earhart Ave., Stockton
Website:   http://sjmastergardeners.ucanr.edu/?calitem=423408&g=3626

A free educational seminar by the UCCE San Joaquin Master Gardeners. Learn about citrus varieties suitable for our climate, planting and care techniques, and more. To reserve a space and class materials, call (209) 953-6100.


REMINDER: Are you interested in becoming a San Joaquin Master Gardener? Completed applications for the 2019 training program must be received by September 28. See http://sjmastergardeners.ucanr.edu/Becoming_a_Master_Gardener/for details and for an application form.

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website: http://sjmastergardeners.ucanr.edu/.

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Experiencing the new in gardening

I discovered a Lily of the Nile, Agapanthus, which was a deep blue at my new home this year. The only ones I had ever known were either light blue or white. So, being a curious gardener, I looked up Agapanthus images using Google. I found that the genus Agapanthus consists of 4 species and the cultivars are often hybrids of these species.  I found a variety of deep blue and bluish-purple colors in hybrids that I had never realized existed and a range of named cultivars. ‘Midnight Blue’, ‘Storm Cloud’, ‘Bluestorm’ and ‘Mood Indigo’ are all a dark purplish blue.  ‘Northern Star’ has tall stems supporting blue violet flowers and petals with dark stripes down the petal’s center.

Even white to creamy white, Agapanthus, have a wide range of cultivars: ‘Alice Gloucester,’ ‘Bressingham White,’ ‘Snowy Owl, and many others. For more information on varieties of Agapanthus see: https://www.gardenguides.com/123357-agapanthus-colors.html

I also discovered that Agapanthus means flower of love, from the Greek agape, meaning love, and anthos, meaning flower. What is not to love about a flower that repeats annually to brighten our summer and fall days? No wonder so many are to be seen in so many front gardens.

Hotlips, a Salvia that attracts hummingbirds and bees

Another plant that I enjoy is ‘Hotlips’ sage (Salvia microphylla). I planted it outside my office window when I first moved in. It replaced a Cleveland sage that had died in the same spot, but ‘Hotlips’ has flourished, growing from a four inch plant to a three-footer in one year. Watching from my window, I enjoy hummingbirds and carpenter bees visiting the plant for nectar. Another beautiful flower at my new home is Black and Blue Hummingbird Sage or Brazilian sage (Salvia guaranitica), a Salvia with intense dark blue flowers with a black calyx. It is beautiful, but

Brazilian Sage is a deep blue and a favorite of bees in my garden.

checking it out, I discovered it can be thuggish and invasive. I think I can deal with that because it is so special.

Three old enemies at my new home are spotted spurge and creeping spurge (Euphorbia maculata and Euphorbia serpens) and field bindweed (Convolvulus arvensis). I have destroyed several thousand of these ubiquitous weeds that are everywhere in my new garden. Spurge is an annual, so if I can just keep them from going to seed, maybe I can get rid of it. I found that seeds of this species have longevity of about 6-7 years, so I need to stay diligent for a few years to be successful. Recently, during a nursery visit I spied spurge growing in several 5 gallon citrus pots—no wonder this weed spreads.

The bind weed is a perennial, so even if I can keep them from seeding, the plants will keep coming back. However, it is possible to eventually starve this deeply rooted perennial if you keep destroying the shoots as they come back. Due diligence is again required.

Recently, I discovered a horned tomato caterpillar eating one of my tomato plants. I found the rascal and put him on a volunteer tomato plant that I didn’t care about. I think it worked because a day later the small volunteer was half eaten. The reason I didn’t kill this creature is that tomato hornworms are the larval stage of white-lined sphinx moths (Hyles lineata) which is also known as

Sphinx moth or hummingbird moth is a beauty

the hummingbird moth.

They are the size of a hummingbird with a 2-3 inch wingspan and also have the same capability of hovering like hummingbirds which is a rare feat in the animal kingdom. They are beautiful, nocturnal and feed on nectar usually preferring white flowers. Fragrant white vining moonflowers (Ipomoea alba) open in the evening when the sphinx moths get started feeding and years ago I observed sphinx moths feeding at moonflowers which I had painstakingly grew from seeds.

When I was a five year old on my Dad’s farm and had no inkling that hornworms became pretty moths, my older siblings and I were sent out to rid 3 acres of tomatoes of hornworms using an inexpensive organic method. We were each equipped with a pair of scissors and, when finding the pest, we cut them in two with the scissors. Of course, if you have ever tried to hunt these green hornworms, you know that they are well camouflaged on the tomato plant. I have no idea how many we missed, but I am certain that a few survived to become beautiful hummingbird moths.

Happy gardening and spare a few tomatoes and their caterpillars for the sake of sphinx moths.

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website:  http://sjmastergardeners.ucanr.edu/CONTACT_US/

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Gardening is a lifelong learning experience

Most of us find gardening a challenge.  So many plants to know and choose from, so many configurations of plants possible and so many things to consider, sun exposure or shade, plant textures, flower colors and advancing verses receding colors. What type and amount of hardscape and paths to include and also styles of gardens and themes, such as pollinator gardens or native plant gardens or Japanese gardens. Landscapes that are bio-diverse are also the best because they help minimize some pests and pest damage as well as being aesthetically pleasing.

Having downsized in this past year to a smaller home and garden, I have a new garden to work in and to learn new ways to garden. Fortunately, the previous owners did a wonderful job of landscaping with a mostly native plant garden in the front and in the back are roses, flowers for pollinators and an area for composting and vegetable growing in raised beds. I added 3 more raised beds making 9 in total. I like to grow a variety of musk melons which takes up nearly two raised beds.  Corn and pole beans take up a lot of room so I gave up the pole beans and the corn in favor of melons and of course dahlias which you can’t buy at the local market.

Gardening is a lifelong activity that requires continued learning and exploration.  It can be a challenge for our brains to keep us young in spirit as we age. Recently, I judged 4-H entries in the youth floriculture show at the Stanislaus County Fair in Turlock. I enjoy my flower judging activity and it can be a learning experience for me as well as for the kids entering their flowers. I score them less than first place for flowers entered past prime, deformed, ungroomed or so short-stemmed that they barely peep out of their containers.  However, most of the entries get a first place and hopefully those getting second place will improve their showmanship next time.

Mexican Bird of Paradise is a collage of bright golds and reds.

At this show, I was treated to two flowers which I had never seen before. I suspect that more than one 4-H kid came from a family growing these flowers as there were four entries each of these unusual flowers. A white cactus flower that was awesome as well as a Mexican Bird of Paradise, which I later discovered is a drought tolerant shrub native to the Mojave Desert. The exact white cactus flower that I saw was not easily identified in Google images as there seem to be several so named. There were also lots of zinnias, dahlias, marigolds, lilies and crepe myrtles which kept me busy for 2 hours scoring them all. It is inspiring to see such interest in flowers by youngsters.

We also need to learn to better use our landscape watering. In our Mediterranean California climate where water supply is getting scanter, water conservation in our landscapes is very important.  Water use per person per day for Californians in July 2016 was about 113 gallons. Traditionally, about 53 percent of household water use is on the landscape. It has likely improved

White cactus flower is about 5 inches in diameter and is awesome to behold.

since then with reductions in lawns and water needy plants.

Recently, at midafternoon and with temperature exceeding 100 ºF; I drove by a yard in my neighborhood where lawn sprinklers were running. When humidity is low and temperatures high,   evaporation is also high. Perhaps 30 percent of the water being applied in the heat of the day is evaporating and not reaching or helping the lawn. To be smart at minimizing evaporation and maximizing efficient use of irrigation water, it is best to water between 4 AM and 8 AM. Watering in the evening is more apt to promote water borne diseases than watering in the early morning and watering in the heat of the day definitely wastes water.

With irrigation controllers it is not hard to be consistently correct with watering times. Also, if you are watering a steeply sloping bank or have heavy clay soils, it is possible with a controller to water for short periods interspersed with no watering periods so that the water has a chance to infiltrate rather than run off.  For more tips on water conserving landscape plants see: https://arboretum.ucdavis.edu/plant-database. Here is to both life-long garden learning and water conservation in your landscape.

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website:  http://sjmastergardeners.ucanr.edu/CONTACT_US/

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Become a UC Master Gardener

If you love to garden, have an interest in lifelong learning, enjoy sharing your knowledge and are committed to community service, the Master Gardener program is the place for you. Master Gardeners are community members who love gardening and are enthusiastic to share their knowledge with others. This program offers comprehensive training in the best home gardening practices and an opportunity to use your knowledge in service to your community. Master Gardeners are helping home and community gardeners reap the maximum benefits and enjoyment from gardening.

The mission of the San Joaquin UC Master Gardeners is to extend research-based knowledge and information on home horticulture, pest management, and sustainable landscape practices to the residents of San Joaquin County. UC Master Gardeners extend research-based information by conducting workshops and demonstrations, diagnosing plant and pest problems, speaking to community groups, utilizing social and print media,  educating teachers and parents at school gardens, and answering gardening questions at local fairs and farmers markets as well as on our email and phone helplines. Master Gardener volunteers help empower neighborhoods to foster healthier gardens, communities and a sustainable environment.

The Master Gardener program began in Washington State in 1972 and quickly expanded to other states. The first University of California programs were established in Riverside and Sacramento counties in 1980. San Joaquin re-launched its program in 2007 and since then, the San Joaquin Master Gardeners have volunteered over 53,000 hours and have earned over 14,700 continuing education hours. The program is funded by the cities and counties of San Joaquin and AB939. We are excited to announce the Stanislaus County will be starting a Master Gardener Program and San Joaquin County will be training those volunteers to help get their program up and running.

Our next training will begin in January 2019 and is open to residents of San Joaquin and Stanislaus counties.  Prospective Master Gardeners will attend an orientation meeting in October and are then interviewed to make sure that they are willing and able to complete the volunteer commitment. Those who enter the program must commit to donating a minimum of 50 volunteer hours the first year to Master Gardener public education projects and 25 hours every year after along with earning 12 hours of continuing education.

The training program will be an extensive 19-week course providing a practical overview of horticultural and sustainable landscape practices. Training sessions meet Wednesdays from January 30 to June 5. Classes are taught by experts from the UC faculty and staff, landscape and nursery professionals, local horticultural educators and certified Master Gardeners that are outstanding teachers, who inspire students. Trainees must pass the weekly quizzes and take home final exam with a 70% or better. Classes will be held on the Robert Cabal Agricultural Center in Stockton. Applications may be downloaded from our website or picked up at our office. The registration fee for this program is $180, which includes a copy of the UC Master Gardener manual as well as other UC home horticulture books and covers class supplies.

After completing this training, newly certified Master Gardeners possess not only increased knowledge but, most importantly, an understanding of how and where to find accurate information to share with the public on all kinds of gardening topics. As a bonus, you also have a group of new friends who share the same interest, enthusiasm and dedication to helping the public. You get to meet other like-minded people as well as learn how to have healthier plants, healthier gardeners, a healthier environment and a healthier community and you choose projects that fit your interests, abilities and skills.

If you want to get involved in your community and enjoy preserving food, the UC Master Food Preservers are also accepting applications for their 2018 training that begins in September of 2018. More information about their program can be found on their website, ucanr.edu/sjmfp2018.

More information about our program and the next training can be found on our website. http://ucanr.edu/sjmg. If you have questions, feel free to contact the Master Gardener Helpline at 209-953-6100.





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The carpenter bee – friend or foe?

We usually think of carpenter bees as those bulky, black bees that buzz loudly around our yards and burrow into wood, earning them a reputation as pest insects to be eliminated. You might be surprised to learn better side of these interesting native bees!

Three different species of large carpenter bees live in California, all belonging to the genus Xylocopa. The one usually seen in our area is the Valley carpenter bee (Xylocopa varipuncta). The females of this species are common and instantly recognizable: black and slightly hairy, with black eyes and shimmering dark wings.  The males are seldom seen but stunning: slightly fuzzy and rich golden-brown in color, with a yellowish head and mesmerizing olive green eyes. Their appearance has earned them the moniker “teddy bear bees.”

Valley carpenter bees (Xylocopa varipuncta). On the left is a black female dusted with yellow pollen (perched on a passionflower, with a honeybee in the background). On the right is a golden-brown male (perched on the flower spike of a Mexican bush sage). Photos © Kathy Ikeda

Despite their somewhat startling size and sound, these carpenter bees aren’t as scary as they might appear. Male carpenter bees can’t sting, and females will sting only if disturbed (and even then, that threshold is high). Their large body size and relatively small wings make their flight look aerodynamically impossible and even comical at times!

Large carpenter bees have earned their name — and a bad reputation — by their practice of nesting in wood. They don’t construct hives like honeybees; instead, the females use their strong mandibles (jaws) to chew a small round entry hole and a narrow, six- to ten-inch-long tunnel into soft wood or the trunks of dead trees (cottonwoods and plane trees are favorites). They then use the leftover sawdust from tunnel excavation to wall off a series of brood cells inside the tunnel. A large mass of pollen and nectar is deposited in each cell, then a single large egg is laid on each mass. The eggs soon hatch and develop into adult bees, which remain in the nest until spring.

Preventive measures are the best way to prevent any structural damage from carpenter bees. They won’t disturb painted, varnished, or treated wood and they will avoid holes and cracks that have been sealed or caulked, so regular home maintenance is an effective deterrent. They also won’t tunnel into composite wood decking. Steel wool stuffed into the nest entry holes will discourage carpenter bees from returning, but the nests must be empty for this technique to work. For more specific information, visit the University of California Integrated Pest Management (UC IPM) website: https://bit.ly/2KSq9jM

Pest control companies used to recommend insecticidal sprays and dusts to eliminate carpenter bees from homes, decks, and other wooden structures. Fortunately, that practice is changing as researchers learn more about carpenter bees’ habits and their beneficial role in our natural ecosystem. As one expert notes, “their contribution to pollination far outweighs any damage to structures.” Also, our California carpenter bee species are far less destructive than other species in the eastern U.S.

Chemical control should never be used as a first line of defense against carpenter bees, because the recommended insecticides also can be lethal to honeybees and a wide range of other beneficial insects (See https://bit.ly/2zj5rVI).

You can encourage large carpenter bees to nest in a non-damaging way by placing a scrap piece of untreated 4×4 redwood post or a log section in a sheltered place in your garden, and pre-drilling it with some shallow holes. The bees will find and enlarge the holes.

California is also home to thirteen bee species in the genus Ceratina, collectively known as small carpenter bees. They look nothing like their better-known relatives; they are tiny (less than ¼ inch long), have narrower abdomens, and are metallic greenish-black in color. They bore into and build their nests inside pithy or soft-cored stems of plants such as elderberries, agave, cole crops (Brassica), and sunflowers. This nesting behavior does not harm the plants.

Both the large and small species of carpenter bees act as valuable pollinators. They visit a wide variety of native plants, ornamentals, and some crops, feeding on the sweet liquid nectar from the flowers and collecting pollen to feed to their young. When they do this, they facilitate plant reproduction by carrying pollen from flower to flower. Read more about carpenter bees and their roles as pollinators at https://bit.ly/1DprK8k.

Narrow, tubular flowers present a special challenge for the large species of carpenter bees; the bees are too big to squeeze inside them to get to the nectar and pollen. In these cases, the carpenter bees engage in nectar robbing: they land on the outside of the flowers and use their sharp mouthparts to pierce them and drink the nectar inside. This doesn’t harm the blooms, but it also means that the bees don’t come in contact with the pollen-laden structures inside the flowers, and in these instances, no pollination occurs. Fortunately, large carpenter bees also visit and are able to pollinate wide variety of plants with more accessible flowers, and the smaller species of carpenter bees — unlike their larger cousins — are able to climb into tube-shaped flowers and pollinate them.

I’ve spent many hours in my garden in close proximity to these fascinating insects, observing them without worry. Valley carpenter bees constructed a nest in our redwood arbor many years ago, but we leave them undisturbed, because their limited burrowing doesn’t compromise the structural integrity. It’s been fascinating to watch them fly in and out of the small nest hole and visit nearby perennials, including two of their favorites, autumn sage and foothill penstemon. I’ve been able to photograph the bees up close and to watch them as they hover nearby; I’ve never once been stung, and have been well entertained.

My carpenter bee verdict: Definitely a friend!

To learn more about the highly diverse species of bees in our state, read the book “California Bees & Blooms: A Guide for Gardeners and Naturalists,” published by Heyday Books. For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website.




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Contemplating climate change and gardening

After several days of scorching temperatures and skies dusky with smoke from local wildfires, it seems an appropriate time to consider how climate change will affect the plant life that gardeners love so dearly.

As our California weather patterns become more unpredictable, it’s inevitable that changes will occur to our local ecosystems. Forests stressed by higher summertime temperatures, more frequent drought conditions, and bark beetle infestations will experience tree die-off at an accelerating rate. Wildfires will become more severe and frequent, burning natural habitat, gardens, and homes. Native plant communities will be forced to migrate to higher elevations as average temperatures rise — or die off if they can’t adapt.  The ability of plants to adapt to changes in precipitation patterns has wide-ranging implications for agriculture, forestry, grazing, the nursery industry, and home gardeners.

California’s water supply, already a critical issue in our naturally arid state, will become an even more pressing issue as our state’s population continues to increase. Mandatory water rationing and water metering for all homes will probably be the wave of the future.

Our family lives in a neighborhood without water meters. We’re extremely conscious about both our interior (home) and exterior (garden) water use, to the point of allowing our never-used front lawn to go mostly brown in summer while we plan a more water-wise landscape. (Sorry, neighbors!) It’s not very attractive at the moment; however, it’s far more discouraging to see other households be so wasteful with precious water. One neighbor runs front yard sprinklers every day on a too-long cycle, leading to wasteful runoff and persistent flooding of a drainage area that leads away from their property. Pay-for-usage water billing (rather than flat-rate charges) will hopefully encourage water conservation and reduce or prevent such misuse.

Weather patterns and water supply are inextricably connected to the health of our gardens and to the productivity of the farming operations that are such a vital part of our county’s economy. The potential effects of climate change are dire, but there is hope. We can all do our part to minimize human impact on our planet and to garden sensibly. Making appropriate adaptations now — such as implementing permanent water conservation measures and switching to water-sensible plants/crops — will help prevent potentially catastrophic consequences in the future.

Here are some ways to make water- and climate-sensible changes to your home landscape:

  • Convert gardens from high-water-use plants to California native plants and low-water-use plants. Consult the WUCOLS IV plant list (http://ucanr.edu/sites/WUCOLS/) to learn more; it classifies hundreds of plant species by their water needs, from very low to high. (WUCOLS = Water Use Classification of Landscape Species)
  • Water plants and lawns deeply and infrequently (rather than shallowly and often). This encourages their roots to penetrate far into the soil, which in turn makes them more resistant to hot, dry weather.
  • When landscaping, use the principle of “hydrozoning,” or grouping plants together by their water usage. That way, irrigation systems can be adjusted to provide only as much water as those plants need. (Intermixing plants with different water requirements results in overwatering some plants to provide enough water to the thirstiest ones.)
  • Use organic mulches in planting beds to conserve soil moisture and keep plant roots cooler.
  • Use your powers of observation to see what plants look best under stressful conditions. Those that thrive are far better choices that ones that don’t. (For example, after the last severe drought, our local neighborhoods were riddled with dead, dying, or badly suffering redwoods and birch trees. These two species are naturally adapted to moist environments and they require lots of water; therefore, they’re poor choices for the Central Valley.)
  • Check your irrigation system to make sure all sprinklers and emitters are working properly, and fix any leaks. Also, watch for runoff; it’s a sign that water is being applied faster than it can soak into the soil. Adjust your irrigation timer to reduce the length of the watering cycle, or water in a series of shorter cycles.
  • Plant area-appropriate, deciduous shade trees on the south and west sides of your home, if possible. They will help shield your house from the afternoon sun in the summer, keeping it cooler and minimizing air conditioner use. In the winter, the leafless trees will allow the sun to warm your house, reducing the need for heating.

Red buckwheat (Eriogonum grande var. rubescens), one of many durable and beautiful California native plants. It’s an excellent choice for a garden adapted to tough climate conditions. (Kathy Ikeda)

I’m using a portion of my yard as a test plot for low-water-use plants, and I’m being intentionally hard on them. Not counting the initial year of plant establishment, this area gets deep, supplemental watering only a few times each year; I rely mostly on natural rainfall. Despite little water and mostly full-sun conditions, these California native plants are thriving and attractive: California fuchsia, California coffeeberry, red buckwheat, foothill penstemon, sedum autumn joy, deer grass, and two varieties of yarrow. Some other non-native plants—bidens, hybrid soapwort, and cape balsam—are also great successes.

One innovative experiment regarding plants and climate change is now under way at U.C. Santa Cruz. The newly installed Future Garden is a joint science and art project to determine which native plants respond best to the conditions expected to occur with climate change. Read more about it at http://ias.ucsc.edu/content/2018/harrisons-future-garden-ucsc-arboretum.

In these times of change, let’s all take the time to be conscious of our gardening practices, and to improve them for the benefit of our community and our planet.

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website: http://sjmastergardeners.ucanr.edu/CONTACT_US/.

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Plant it right and don’t plant invasives.

PlantRight is an organization that works to reduce the number of invasive plants sold at nurseries in California. Master Gardeners and other volunteers have helped conduct eight annual surveys to assess how many invasive plants are currently for sale and to encourage nurseries to stop selling such plants. This year, PlantRight is not doing a nursery survey, but instead is concentrating efforts on outreach to landscape professionals (e.g. architects, designers and contractors), and to water districts promoting sustainable landscaping. In the 2017 survey, the rate of nurseries selling invasive plants continued to decline; dropping from 44 percent in 2014 to 29 percent in 2017. For a list of invasives see: https://www.epicgardening.com/invasive-plant-species-in-california/

I have battled many invasive, obnoxious plants in my lifetime, so I am always glad to warn others about the hardships that such plants can bring your way. I can say that I have not won a battle with invasive plants. When I bought my farm 42 years ago I inherited some nasty plants along with the beautiful redbuds that caused me to name the place Redbud Farm.

Periwinkle (Vinca major) was growing in several places and it still is today though greatly reduced in abundance. I tried hard to eradicate it, but it has proven very resilient. The roots must be removed or it comes back and I suspect residual seeds too. It has become a major invasive plant in the shade of redwood trees on the north coast where it displaces native understory plants.

Another invasive is Algerian Ivy (Hedera algeriensis) along with others of its ilk who provide good rat habitat. Although I removed it long ago, I keep finding new plants coming up and I am uncertain if this is due to birds dropping seeds or residual seeds from the original plant. It is mostly now a nuisance weed. Birds dropping seeds reminds me of Privet (Ligustrum sp.) whose seeds cause lots of weed trees requiring vigilant weeding, even if you don’t have one in your garden.

Italian Arum (Arum italica) is a woodland shade-loving plant that grows from corms. It resembles a jack-in-the-pulpit with large, arrow-shaped leaves. It grows in the winter and fades away with summer weather but leaves a large seed stalk with orange seeds. It reproduces with seeds along with deeply rooted corms that divide. It naturalizes readily and did so long before I bought the farm, so basically I was stuck with it.

In small locations you can cover the plant with a board and starve the corms for a year or more. This approach is not going to work when it is abundant everywhere. Herbicides do not work and digging out the corms is only practical in small areas. It is difficult to remove all the small corms.

I did remove Arum seed stalks before the seeds were scattered which perhaps helped curb their spreading. Years ago, to develop my step-daughter’s work habits, I paid her 2 cents for every seed stalk pulled and she pulled a few hundred. However, since all parts of the plant are poisonous it is wise to be careful when being in contact with this plant. Would you believe that on-line nurseries will sell you, for only $25 for 5 corms, a bundle of misery and trouble?

Small-leaf spiderwort (Tradescantia fluminensis) is a shade-loving creeping perennial herb that roots at nodes, I thought I had gotten rid of this plant, but it re-emerged to take over all shady understory areas. It smothers everything with vigorous growth and the rooted sections break off easily so removal is difficult. Herbicide such as a 3 percent glyphosate is recommended, but this may not be a solution in circumstances where other plants are present.

Spiderwort is a problem in Florida and in New Zealand where it covers vast areas of understory forests. Recently, I belatedly saw some being sold at a plant sale that I was involved with. I hope none were purchased and next year I will insist we not offer it for sale.

Bermuda buttercup or Buttercup oxalis (Oxalis pes-caprae) is an invasive impossible to eradicate as it grows from bulbs and it makes a bunch of new little bulblets every year. The flower is pretty and blooms in late winter/spring. I had to acquiesce to living with it.

Bermuda buttercup or Buttercup oxalis (Oxalis pes-caprae) is an invasive impossible to eradicate as it grows from bulbs and it makes a bunch of new little bulblets every year. The flower is pretty and blooms in late winter/spring. I had to acquiesce to living with it.

Last week was Invasive Species Action Week in California to awaken the public to the downside of invasive species. I wrote this article before I knew that. For more information see: https://www.wildlife.ca.gov/conservation/invasives/action-week . Sometimes, the only way to get rid of invasive plants is to sell the farm; so I did. To all gardeners, I wish you happier gardening sans invasive plants, so plant carefully.

If you have a gardening related question, you can contact the UC Master Gardeners at 209-953-6112. More information can be found at: http://sjmastergardeners.ucanr.edu/


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Some garden myths to lose

In this new age of ‘Fake News’ when facts are branded as fake and lies are freely airborne, it might be appropriate for gardeners to sort myths from garden facts.

Planting by the moon. I had a gardening friend who swore that you should plant root crops by the dark of the moon. I don’t automatically discount such advice, but finding credible evidence that this is true is non-existent.  True, the moon does affect ocean tides, but its effect on smaller bodies of water is nil and the likelihood that it can affect water movement in plants or germination has never been demonstrated. For more information on this myth see: https://www.gardenmyths.com/planting-moon-calendars/ .

Sunshine focused through raindrops will burn plants. Watering plants in the sun should not be done because droplets of water act like magnifying glasses and will burn holes in the plant’s leaves. If this is so, farmers would encounter huge losses after each daytime rainstorm. Sorry, but there is no way that a drop of water can raise the leaf temperature to a burn.

It is advisable to water gardens in the early morning hours to conserve water and to avoid nurturing moisture-fostering diseases. Plants so watered will dry as the sun shines; unlike plants watered in the evening or at night which will dry off much more slowly thus enhancing disease possibilities.

Copper strips keep slugs and snails away. This is a touted way (though not inexpensive) of keeping these pests from the vegetables in your raised beds. Allegedly, the copper induces an electric charge that deters the pests. Several tests of this shown on YouTube tend to disprove this method. A couple of tests used pre-1981 actual copper pennies and other copper materials in an experiment with snails and slugs. They observed the pests sliding across the copper undeterred. I am not sure that this is a definitive disproof of copper’s deterrence, but it does strongly suggests it doesn’t work. See: https://www.gardenmyths.com/how-to-get-rid-slugs-with-copper/.

There are ways to curtail snails and slugs and handpicking with a flashlight in the evening, early morning or during or after irrigation/rain will reduce their numbers. Diatomaceous earth and wood ashes piled in rings around plants will protect them as long as the materials are not wet and dry egg shells may work too. Baits using iron phosphate which are harmless to pets and children also can be used. Upturned citrus, shingles or boards with space beneath will provide hiding places that can be checked in the morning for pest disposal.

Use coffee grounds to acidify soil. While coffee grounds are acidic, mixing them into the soil would affect pH very slowly. Fresh coffee grounds tie up nitrogen as they decompose and this can adversely affect plant growth. It is best to use coffee grounds in your compost bin to facilitate the breakdown of leaves or high carbon materials. To acidify soil for acidophilic plants such as azaleas, rhododendrons or blueberries it is best to use soil sulfur as directed on the package.

Newly planted trees should always be staked. Unless the tree is top heavy or in an especially windy location, it does not require staking. Movement is good for young trees as the trunk will grow thicker and stronger when not immobilized by staking. Last winter, I pruned in a small local orchard where young fruit trees had been properly staked as if they were landscape trees. It should never have been done since fruit trees, when properly pruned at planting, need no staking. Unfortunately, they were not properly pruned at planting either. If properly staked, movement should be allowed to help strengthen trunks. Most trees should have stakes removed after 6 months to assure development of strong trunks.

Gravel in the bottom of containers improves drainage. A myth slow to die and one that actually is counterproductive with an increase in the possibility of root rot, not less, with the use of gravel. The water saturates the soil above the gravel as gravity moves it downward, so basically it makes the effective size of your container smaller by moving the saturation pool of water higher in the pot. It is better to use a potting soil that is porous and well drained. Adding perlite or organic matter will increase drainage and soil can be prevented from leaving though the bottom hole by covering it with a piece of screen or landscape cloth.

Adding sugar to the soil will yield sweeter tomatoes. Sugar in tomatoes is the result of photosynthesis. Adding sugar to the soil might feed some soil bacteria, but if you want sweeter tomatoes add sugar after slicing. Some tomatoes are genetically programmed to be sweeter than others and I vote for Early Girl as a sweet one. Happier gardening if you lose the myths.

If you have a gardening related question, you can contact the UC Master Gardeners at 209-953-6112. More information can be found at: http://sjmastergardeners.ucanr.edu/

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Protecting Plants from Summer Heat

By Kathy Ikeda

Scorching days have arrived! All but the hardiest of us wilt when outdoor temperatures hit the 90s and 100s, and we seek refuge in air-conditioned places or in water-cooled

Foliage damaged by weather (sunburn).

outdoor areas. Plants don’t have that luxury; they’re literally rooted where they are, and they sometimes need our help to deal with the Central Valley sunlight and heat.

Summer weather can damage plants by stripping them of the moisture they need or by exposing them to more heat or light than they’re adapted to handle. Higher than usual air temperatures, intense light, and overheated or too-dry soil can harm a plant’s leaves, stems, and roots. Wind can further worsen the effects of hot air.

Like humans, plants rely on water partly to cool themselves: we sweat, plants “transpire.” Transpiration is the process by which plants absorb water through their roots, move this water upward through the part of their vascular system called xylem, then lose this water through tiny pores called stomata on the leaf surfaces. The transpiration rate rises in hot temperatures; a plant’s water loss generally doubles with every 18-degree increase.

Plant species vary in the amount of water they need to resist heat and maintain good health (hence their classification as low, medium, or high water use). New plant growth, tender seedlings, fruits and vegetables, and cool-season annuals are particularly susceptible to sun-related damage.

Plants exhibit different levels of heat damage, and it’s important to know the distinction. Wilting is the drooping or shriveling of plant tissues that occurs when they lack sufficient water; it’s reversible if plants are watered in time. (Large-leaved plants will usually wilt a little during peak daytime heat even with adequate water, but will recover when temperatures cool.) Heat stress is when plants begin to suffer irreversible heat-related damage; at this stage, some plants will try to conserve water by dropping leaves or buds. Sunburn (or “leaf scorch”) is when a plant’s leaves or non-woody parts are permanently and severely harmed by excessive heat or sunlight; leaves develop dried brown patches or margins and they eventually wither and fall off. Sunscaldis the cracking, discoloration, and warping of bark that occurs when the trunk or branches of a woody plant get too much sun exposure; the damage is permanent and very harmful since it increases the plant’s disease susceptibility.

A toyon with damaged bark from sunburn after canopy pruning. Photo by Jack Kelly Clark.

Follow these simple guidelines to minimize heat damage:

  • Conserve soil moisture and protect plant roots from excessive heat by covering bare ground with a 2- to 4-inch-thick layer of organic mulch—wood chips, shredded bark, leaves.
  • Don’t place inorganic mulches—sand, pebbles, rocks, shredded rubber—or black-tinted mulch near plants in sunny locations (with the exception of desert-adapted plants), because these materials collect and radiate heat.
  • Follow the principle of “right plant, right place.” Select plants adapted to our Mediterranean climate and choose planting locations with proper exposure. (No shade-loving plants in full sun!)
  • Don’t heavily prune trees and shrubs in summer, because this can suddenly expose tender bark to the sun’s intense rays. It also encourages a flush of heat-sensitive new growth and places additional energy and water demands upon heat-stressed plants.
  • Avoid planting during peak summer heat; this stresses plants and compromises their chances of successful establishment. Delay planting until fall, or (if you must plant this season) wait until a cooler spell, plant in the evening, and water deeply after planting.
  • Keep potted plants well watered and (if possible) move them to shadier locations. Use light-colored or plastic containers, which absorb and transmit less heat than dark-colored containers or those made of ceramic, cement, or metal. Hydrogels (water-retaining polymer granules) can be mixed into potting soil to help hold moisture.
  • Whitewash trunks of young trees to help prevent sunscald. Mix equal parts water and white interior latex paint, then apply it from 1 inch below ground to at least 2 feet above ground.
  • Use strategically placed shade cloth to shelter plants.
  • Ensure that plants receive appropriate and consistent levels of water, and check irrigation systems for proper operation. Do this yourself, or enlist the services of a Qualified Water Efficient Landscaper (www.qwel.net).

For gardening related questions, call the UC Master Gardener office at 209-953-6112, or use our website: http://sjmastergardeners.ucanr.edu/CONTACT_US/.


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