Washington State University Extension

Garden Tips

Archive for January 2010


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

It’s probably wishful thinking, but the new gardening season will be here before we know it. However, we still have a some down time that we can take advantage of by planning our gardens and ordering seed. The Mailorder Gardening Association offers a catalog glossary to help gardeners interpret the gardening “language” you may not understand. Not a bad idea, so here are some that I often get questions about.

Determinate(D) and Indeterminate(I): This is a term used to describe the different growth habits of tomatoes. If a variety is labeled as “indeterminate,”it means the plant will keep growing as long as it stays warm. Indeterminate varieties are the vigorous vine types that are hard to contain. Large cages or trellises will work best in keeping the vines off the ground. Determinate varieties of tomato grow to a certain size and stop. They are more compact and easier contain. Most of their fruit ripens around the same time. The fruit of indeterminate varieties ripen over time as the vine keeps growing.

OP or Open-Pollinated: You’re likely to see this term used in catalogs that focus on heirloom vegetables and flowers. It means these varieties have been left to nature for pollination to occur. If the seeds are saved from these varieties, they’ll produce plants and fruit that is identical to the parents. This is how heirloom vegetables can be handed down from generation to generation. Using the right techniques, you too can save their seed from year to year, without needing to buy the seed again.

Hybrid: Hybrids are in a way the opposite of open-pollination. They are varieties that have been created by controlling the pollination between two different varieties. This isn’t genetic tinkering on the cellular level, but is controlled plant breeding. Hybrids are the result of cross breeding two varieties. When the seed of hybrid plants are saved and planted, the progeny will likely not be identical to the parent hybrid plants.

Quarantine: Some catalogs will note that they can’t ship certain plants into the state of Washington. It may seem like discrimination against Washington gardeners and our venerable state, but it isn’t. They can’t ship into our state because they’re abiding by Washington State Department of Agriculture Quarantines. The quarantines are aimed at preventing certain diseases, insect pests, and weeds from entering our state. This is especially important because of the importance of agriculture to our state’s economy and the impact these pests could have on our commercial agriculture, especially the wine grape and tree fruit industries.

If it’s an ornamental tree, shrub or perennial, the nursery may simply not want to go to the trouble or expense of having the plants inspected for evidence of an infestation of certain insects pests. The Japanese Beetle is one of these insect pests. WSDA requires that each shipment of plants from any of the 34 quarantined states must be “accompanied by an official state or federal certificate certifying that the regulated article has been treated by WSDA approved methods and procedures to ensure that all Japanese Beetles have been eradicated. ” These quarantines are made with careful consideration to protect, not only Washington agriculture, but also Washington gardeners and their plants.

Resistance: Some types of vegetables are susceptible to certain plant diseases. Plant breeders have endeavored to create varieties that are resistant to the diseases most troublesome to a particular commercial vegetable crop. It’s important to point out that resistance is not immunity. Listed after the variety name, “V” indicates resistance to Verticillium Wilt, “F” to Fusarium Wilt, “N” to Nematodes, “T” to Tobacco Mosaic Virus, “A” to Alternaria alternata (crown wilt disease), and “L” to Septoria Leafspot. In our area, I would look for varieties that are at least “VFN,” that is resistant to verticillium wilt, fusarium wilt, and nematodes.

Published: 12/26/2009 3:24 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

It’s a season for giving and sharing, so this is a good time to talk about gardeners sharing with others. Our local WSU Extension Master Gardeners regularly donate the produce from the vegetable garden in their Demonstration Garden. It’s a simple act that can have a big impact.

Making a great big impact is the “Plant a Row” or PAR program started by garden columnist Jeff Lowenfels in Anchorage, Alaska. Lowenfels used his column to ask gardeners to plant a row of vegetables for Bean’s Café, a local soup kitchen. This effort was so successful that Fell introduced the idea to the Garden Writers of American (GWA)as a national program.

A little slow at first, it took five years to reach the first million pounds of donated produce. Then it grew like Jack’s beanstalk, taking only two years for the second million pounds. Since 1995 over 14 million pounds of produce have been donated by PAR gardeners across the country. PAR estimates that each pound of food supplements four meals. No federal subsidies and no government involvement was needed to make this program a success, just gardeners helping others.

In the coming year, PAR hopes that Amercian gardeners will donate one million pounds of food. This can happen if 40,000 gardeners each donate 25 pounds of produce. This is approximately one full grocery bag of produce. It’s easier than you think. You may not even have to plant an extra row or extra plants in your garden, just pick your produce regularly and keep the plants you have producing.

America’s Grow-a-Row is a very similar program. It stresses not just feeding the hungry, but feeding them with healthy produce. Their mission is to add fresh vegetables and fruit to low budget diets. America’s Grow-a-Row was started by Chip Paillex a volunteer who decided to answer the call of the local food pantry in Pittstown, New Jersey. The food pantry requested that local gardeners donate their extra garden produce. Paillex did more than that. He grew an entire garden, donating about $3,000 worth of produce by the end of the season.

Paillex, realizing that there was only so much he could grow with his little garden patch, contacted a local farm and asked for some help. They donated a quarter acre of space, vegetable transplants, and seed. Another farm also donated garden space. Members of Paillex’s church stepped up to help tend all this new space. By the end of the second season, they had raised and gleaned over 14,000 pounds of food for the food pantry.

Like PAR, the America’s Grow-a-Row was an idea that caught on. The group received more free seed and offers of help throughout the community. In 2008, an astounding 110,000 pounds of “fresh, healthy produce” were donated. All because one gardener wanted to help.

Here in Washington, garden personality and seed purveyor, Ed Hume has been supporting gardeners’ efforts to help the hungry by supporting GWA’s Plant a Row program. Ed Hume Seeds has donated at least 10,000 packets of seed (mostly carrots) in support of the program since 2002. They also donate about 1,000,000 packets of year-old seed to international charities and last year they donated approximately a ton of seed to charities in New Orleans to help with rebuilding. Imagine how much produce resulted from a ton of garden seed!

So as we reflect on our blessings during the holiday season, let us keep in mind that just one gardener can make a big impact on hunger in our community. Consider planting a little extra for others as you plan next year’s garden. Happy Holidays!

Published: 12/19/2009 2:23 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Let’s face it, it’s winter and it’s already been very cold outside. There’s not much for gardeners to do other than worry if their perennial plants, trees, and shrubs made it through the recent frigid weather unscathed. I opt for staying warm and sitting back with a good gardening book. I thought you’d like to know some of my favorites.

One book I simply call “Dirr,” but more officially it’s known as the “Manual of Woody Landscape Plants” by Michael A. Dirr. The fifth edition of this tome sits front and center on my desk. When I bought this edition, after having two of the previous ones, Dirr had indicated that it would be his last update. However, it wasn’t. Dirr has now updated his manual and the sixth edition is a major revision with “expanded descriptions of former entries and 2000 new species and cultivars.”

What I like about Dirr’s book is that it provides cultural information on thousands of woody plants, including trees, shrubs, and vines. What I like the most is his opinionated commentary. If he thinks a plant has no redeeming value or is overused, he says so. When it comes to woody plants, you will not find a more accurate reference in regards to plant size, growth habit, flower, fruit, and foliage characteristics, rate of growth, hardiness, growing requirements, common pest problems, best use in the landscape, and propagation. Weighing in at over five pounds with 1325 pages, the hardcover edition of this sixth edition will set you back about $100, but it’s worth every penny, if you’re a woody plant enthusiast like me.

When it comes to vegetable gardening, my favorite reference is “Vegetable Gardening in the Midwest” from University of Illinois Extension. I know we’re not in the Midwest, but the basic vegetable gardening information it contains is straightforward and uncomplicated. It has good garden preparation and planting information which has to be adjusted some for our region, but what I like the most is the cultural information provided on 41 “major” vegetables (like tomatoes) and 20 minor vegetables (like okra) and herbs. Not only is cultural and harvesting information provided for each crop, but each also has a section of the most commonly asked questions and problems for that veggie. At $27.00 the publication is a bargain. It’s a reference I often use when I’m asked a vegetable gardening question. It can be obtained directly from the University of Illinois Extension at

If you want to read a garden book that reaches your heart, pick up “Deep in the Green – An Exploration of Country Pleasures.” This book was given to me a long time ago as a hand-me-down by a friend who was given the book by a friend. It qualifies more as garden literature, than a garden reference though. Written by Anne Raver, a gardener herself and a garden columnist for the New York Times, each chapter is a heartwarming account of her garden experiences and reflections on life, as well as gardening. Some chapters, like the ones about her relationship with her aging parents, touch your heart. Others like the one about mowing with a reel mower are humorous and self-deprecating. I read many of the chapters this summer out in my garden. It was a relaxing way to end each day and enjoy the delights of my garden.

There are lots of great gardening books. Whichever ones you pick, stay warm, sip some tea, and take time to relax this winter.

Published: 12/12/2009 1:58 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

I bet you’ve seen the many beautiful poinsettias for sale in local nurseries, grocery, hardware, and discount department stores? I thought you might like to learn a little more about this very popular holiday plant. Here is some interesting poinsettia trivia:


Did you know that when grown outdoors in subtropical climates, the Christmas poinsettia grows into a large shrub or tree that can reach a height of 16 feet? I’ve seen them myself. One year my family spent the holidays in Florida. I was just a young girl, but I still remember being impressed with the pretty poinsettia bushes flowering in the landscapes. The native poinsettia species, Euphorbia pulcherrima, is native to Mexico where it can be found growing wild in tropical forests.


Poinsettias flower in response to the longer nights of fall and winter. This happens naturally when poinsettias are grown outdoors in subtropical climates, like Florida. In the past, greenhouse growers had to “trick” them into flowering in time for the holidays. In the fall, they would cover greenhouse poinsettias with light-blocking black cloth to keep any light from reaching them. Typically, growers started covering the plants in late September to early October and provided 12 to 14 hours of darkness each night. They also provided at least eight hours of bright light each day. Some cultivars still require covering for early flower production, but modern breeding has produced cultivars that flower on their own early enough for the holiday season without using black cloth to simulate long nights.


In 1919, the death of a toddler in Hawaii was incorrectly attributed to the child eating poinsettia. Ever since then poinsettia purveyors have been trying to correct the misconception that the poinsettia is poisonous. Research studies at Ohio State University found that the poinsettia is not toxic and the POISINCDEX Information Service indicates that there is no reasonable poisoning risk to children or adults from potted poinsettias in the home.

How about pets? According to the ASPCA, the poinsettia is not considered extremely toxic to cats and dogs. Ingestion “typically produces only mild to moderate gastrointestinal tract irritation, which may include drooling, vomiting and/or diarrhea.” While eating poinsettias is not usually fatal for pets, it’s best to keep kitties and puppies from eating them.

I wonder if the myth that poinsettias are poisonous persists because it’s a member of the Euphorbia or spurge family. Some members of the spurge family are considered poisonous because of their latex-like milky sap. Their sap is caustic and can cause skin irritation, inflammation and blistering. The sap can also irritate mucous membranes and the digestive tract if eaten. Spurges with toxic sap that are familiar to gardeners are Snow-On-The Mountain (Euphorbia marginata), Daphne (Daphne mezereum), and Creeping Spurge or Donkey Tail (Euphorbia myrsinites). If you get the milky sap of any spurge on your skin, be sure to wash it off as soon as possible.


According to the University of Illinois “poinsettias are the best selling flowering potted plant in the United States” with over $200 million worth of poinsettias sold over a six week period during the holidays every year. Interestingly, 80 percent of the over 60 million plants sold are purchased by women and 80 percent of those making poinsettia purchases are over 40 years old.

The first poinsettias introduced to American consumers were red, but plant breeders have worked over the years to develop white, pink, rose, wine red, orange, apricot, and even purple varieties. However, red is a traditional color for the holidays and 80 percent of American consumers buy red poinsettias, with white poinsettias coming in a far second and pink ones are third. What color poinsettia are you going to buy?

Published: 12/5/2009 1:46 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

I’d call it limbs falling out of trees, but the technical term is “branch failure. The winds last week in our region and elsewhere in the state led to a number of “branch failures.” When wind gusts blow and twist about tree tops, there’s always the chance of limbs and branches breaking. Rarely do limbs drop from trees for no reason. When the “bough breaks” and falls in wind storms, there are three very predictable reasons.

Past tree topping is at fault for many limbs that break from trees. When trees are topped the regrowth that develops are called water sprouts. These water sprouts are not strongly attached to the stem or branch on which they form. As they grow larger and heavier, they’re more and more prone to breakage in windstorms because their weak attachment can’t hold their weight.

This type of failure can be avoided by not making topping cuts on large tree branches and major limbs. If needed, tree height and crown density can be reduced with thinning cuts that retain a tree’s natural form and don’t leave stubs. With thinning cuts, branches are cut back to side or lateral branches that are at least one-third the diameter of the ones being removed. The growth that is stimulated by thinning cuts will be evenly distributed around the crown, in contrast to the vigorous, weakly attached water sprouts that result from topping cuts.

Wood rot is another problem that results from topping. A branch stub left from a topping cut never closes over, leaving the branch wood exposed and prone to invasion by wood rot fungi. Once rot invades the heart wood of a branch or trunk, it loses its structural integrity. Decayed branches are very vulnerable to wind breakage. Also, decayed branches provide poor support to branches that developed from water sprouts.

Wood rot is best avoided by making proper pruning cuts at the base of a branch, but outside what is called the branch collar. Treating pruning wounds with pruning paint or “wound dressing” materials will not prevent wood rot. In fact, these materials can actually encourage wood rot by sealing in moisture and excluding light, creating a better environment for wood decay organisms.

The third common reason for branch or limb failures are narrow or V-shaped crotch branch angles. These narrow angles are weak connections between two branches or limbs. The narrower the angle, the more poorly they’re bonded together. Stress put on these weak attachments by wind or ice can cause them to split. This is particularly true as the branches or trunks grow in girth, pushing against each other.

Certain trees, such as Bradford pear, green ash, and silver maple, are prone to developing narrow branch angles. However, other trees may also have narrow crotches due to poor training as a young tree. The best way to avoid problems is to refrain from buying trees that have already developed narrow crotch angles or trunks with forks. Forks are “co-dominant leaders” or competing leaders that have developed instead of a single trunk or “leader.”

When buying a tree, look for ones with good branch angles of 60 to 75 degrees. Avoid any trees with trunks that already have forks. Also, branches should be evenly distributed around the trunk, not all on one side or with multiple branches arising from one point.

Protect yourself from falling branches by never topping trees and by buying well-structured trees that won’t set you up for failure in the future.

Published: 1/21/2010 1:57 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Just like the tomato is the staple crop of the home veggie garden, the rose has been the universally favored flower of the garden. I know many gardeners who have ten rose bushes or more. However, I’ve noticed that fewer gardeners today are indulging in their passion for roses on a large scale. The reasons? Modern hybrid teas and floribunda shrubs are a lot of work, requiring regular pruning, deadheading, and pest control. Also, with the emerging trend of smaller yards, gardeners don’t have the room to overindulge in their love of roses.

To meet the changing needs of gardeners, rose breeders have worked at developing roses that are more compact and have good repeat bloom. They’ve also endeavored to create roses that are hardy, don’t sucker, are resistant to disease and insects. Many of the new roses that meet these criteria are placed in the general category of “shrub roses.”

However, the “shrub rose” category is a bit murky and seems to be a catch-all term for roses that don’t fit in anywhere else in the traditional categories, such as hybrid teas, floribunda, climbers, or miniatures. A rose classified as a “shrub rose” may be compact and easy to fit into a garden with other plants or it may be as tall as six feet or more. In retail catalogs, some growers have decided to aptly name the improved modern shrub roses, “landscape roses.”

Meidiland Landscape Roses, developed by French breeders, were perhaps the first of the newer shrub roses to catch the fancy of American gardeners with 1987 All America Rose Selection (AARS) winner, Bonica. It’s a vigorous shrub rose growing to five feet tall and wide with clusters of single soft pink flowers. Members of the Meidiland Landscape Rose family are known for their easy maintenance and abundant bloom.

The Knockout series of landscape roses, developed by Bill Radler is a well known line of modern landscape roses. In 2000, Radler introduced the first of the series, ‘Knockout,’ another AARS winner. Now called a “classic,” ‘Knockout’ was the first in this illustrious series. It filled the criteria for the modern shrub roses with compact growth (height and width of 3-4 feet), great hardiness, disease resistance, and even drought tolerance.

The Carefree series is another popular named series of roses launched in 1991 with

Carefree Wonder

. It has semi-double hot pink and white flowers and grows five feet in height. This year ‘Carefree Spirit,’ with single bright red flowers is a 2009 AARS winner.

Pruning and deadheading are two of the most onerous tasks of modern hybrid roses, but the attractive feature of many of the landscape roses is that they don’t require as much detailed pruning. All that’s needed are hedge shears to prune shrubs back to half their height in late winter. For those who feel they must, the shrubs will also benefit from pruning out some of the oldest canes and any dead or weak growth . Deadheading is easy, especially since many landscape roses are self-cleaning, not requiring pruning to remove spent blooms to prompt re-bloom. If they’re not self-cleaning varieties, all that’s needed is hedge shears to shear off the spent blooms.

If you love roses, but don’t want all the hard work that can come with growing them, consider planting a few of the new landscape roses. After all, a rose is a rose, these are just easier to grow.

Published: 11/21/2009 12:49 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Are you old enough to remember the “green revolution” of the 1970

s when live houseplants were popular? Veritable jungles grew in homes across the county.

While many grandmothers had perfected the indoor growing of African violets, the public wanted more choices. Universities researched the types of plants that could be grown under the low level of light found in buildings. They also developed soilless potting mixes that provided better growth than plain unsterile garden soil. Garden writers wrote book after book on the care of houseplants. An entire indoor plant industry was “sprouted” and there were live plants growing in shopping malls, office buildings, and homes. The more plants, the better.

So why have homes and businesses shifted from their tropical plant decor of the 70s and 80s to a paucity of live plants today? I don’t know, but I can guess some of the reasons. Houseplants take effort and time, both precious commodities with today’s very fast paced lifestyles. Houseplants can be messy with dead leaves, repotting, and water leaking from pots. If not nurtured and provided with enough light, houseplants can turn into downright ugly or dead specimens.

In the late 1980s, when the indoor plant craze had started to wane, NASA research revealed the ability of certain indoor plants to help purify air by removing harmful organic pollutants. Because of the energy crisis and the skyrocketing costs of heating and cooling, more and more homes were being built to be energy efficient. The more energy efficient the homes, the greater the buildup of these harmful organic pollutants of trichloroethylene, benzene, and formaldehyde.

These pollutants were given off by the various adhesives, building materials, foam insulation, paint, and other finishes used to construct furnish, and clean our homes. While the standards for many of our building materials and paints have changed to reduce our exposure to these air pollutants, they’re still present in our homes.

When NASA research revealed that certain indoor plants could help “clear the air,” it was presumed that it was the green leaves that did all the work. Later research revealed that it was the plant, the roots, and the soil working together. For plants to be most effective as air purifiers, it’s desirable to “maximize air exposure to the plant root-soil area.” (Researchers noted that even better results could be obtained if fans with charcoal filters were used to pull air into the soil. )

The general recommendation based on the NASA research is to place at least 15 adequately sized houseplants (plants in six to eight inch or larger pots) in a 1,800 square foot house. The plants found to be most effective at cleansing polluted indoor air are (Aglaonema modestum) Chinese evergreen, (Chamaedorea sefritzii) bamboo or reed palm, (Chlorophytum comosum) spider plant, (Dracaena deremensis) Janet Craig or Warneck dracaena, (Dracaena fragrans `Massangeana

) cornstalk dracaena, (Dracaena marginata) red-edged dracaena (Epipiremnum aureum) golden pothos, (Ficus benjamina) weeping fig, (Hedera helix) English ivy, (Philodendron domesticum) elephant ear philodendron, (Philodendron scandens `oxycardium

) heartleaf philodendron, (Philodendron selloum) selloum philodendron, (Sansevieria trifasciata) snake plant, and (Spathiphyllum) peace lily. While not year-round houseplants, potted mums and gerbera daisies were also very effective as air purifiers.

So go green, start a jungle in your house and clear the air.

Published: 11/14/2009 12:23 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

It seems like fall has just breezed by us, figuratively and literally. In early October we were enjoying some gorgeous autumnal days and then frost, wind and rain suddenly arrived. We were a bit spoiled last year, but wouldn’t it have been nice to have a few more balmy fall days? This abrupt arrival of cold frosty weather has gardeners wondering if it’s too late to do some of the gardening tasks they had planned.

Is it too late to fertilize my lawn? No, early November is one of the most important times of the year to fertilize your lawn. No special “winterizing” lawn fertilizer is needed, but I would recommend one that has at least 50 per cent of its nitrogen in a slow-release form. A good ratio for a lawn fertilizer is 3:1:2, for example a fertilizer labeled as 19:6:12 with over 50 per cent “slow” or “controlled-release” nitrogen. If you can’t find one at your favorite garden store, try a local farm and garden store or agricultural chemical supplier.

Is it too late or too early to put my mower away for the season? I know you want to stop the unrewarding task of mowing, but if your lawn is still growing you should keep mowing it at the recommended height of 2.5 inches. Leaving the grass long can encourage diseases. Mowing extra short can stress your lawn, making it more vulnerable to the stresses of winter cold.

The WSU Extension Master Gardeners diagnosed my lawn as having excessive thatch and recommended dethatching with a power rake. Is it too late to do it now? Yes, you should wait until spring when things start warming up and the grass starts growing again. However, it’s best to get your dethatching done before the middle of April.

Is it too late to plant trees and shrubs? No, now is a good time to plant trees and shrubs. The crowns of deciduous trees and shrubs are dormant, but the roots can still grow when the soil temperature is above 40 degree. This allows them to grow roots and become better established before the heat of summer. However, you must be able to water them in and keep the soil moist if the weather turns dry and stays mild. Overcast and cool foggy or misty days make us think the soil is moist when it isn’t. To protect the newly installed plants, the best bet is to check the soil and water them if the soil is dry. If you want to plant trees and shrubs in the fall, you must be able to provide them with adequate soil moisture if nature doesn’t.

Is it too late to plant spring flowering bulbs? No. You may still plant your tulips, daffodils, crocuses, and other spring flowering bulbs. Just be sure to plant them at the proper depth (usually noted on the package) and then water them in to settle the soil around the bulbs. Like newly planted trees and shrubs, bulbs also need soil moisture in the fall and mild parts of winter. This is needed for the development of roots and will promote healthy plants that will bloom more than one year.

Is it too late to plant the mums I planted in my fall container gardens in my garden? No, even if they’ve been killed by hard frost, go ahead and plant them in the garden. What have you got to lose? Once again, be sure to water them in to help settle the soil. I did this with two little mums last fall and you’d be amazed how much they grew this past summer.

Is it too late to start a compost pile? Certainly not, go ahead and build your compost pile as you clean up your garden. Moisture is needed for the decay process, so you may need to add moisture if your materials are very dry. Don’ forget to add enough “green” or high nitrogen materials to feed the microbes responsible for the initial decay process.

Published: 11/7/2009 12:00 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

“Belly up to the bar boys!” I remember this phrase from the old movies that I watched as a teenager. When I think about tree borers finding a stressed shade tree in our area, this phrase comes to mind. An increasing number of shade trees in our region are being attacked by boring beetles and moths.

The most common boring culprits are bronze birch borer attacking birch; locust borer attacking black locust trees; the ash borer attaching ash; and both carpenter worm and willow borers attacking willows, cottonwoods, and poplars. There’s also the redheaded ash borer that attacks ash, as well a number of other hardwood shade trees.

Back in the “old” days long-term residual pesticides, such as lindane, were relied upon to control boring insects in trees, but both lindane and Dursban (lindane’s replacement) have been banned because of their detrimental impact on humans and the environment. Since the loss of Dursban in 2001, gardeners haven’t had chemicals available that provided cost effective and reliable control of borers.

The sprays of the past (and present) were aimed at controlling adult borers as they emerged from trees and newly hatched borer larvae before they found their way under the bark. This was done by applying spray applications to the bark and trunk of the trees. Many of the borers that attack shade trees emerge over a relatively long period of time. The older, banned chemicals worked well for borer control because they had a long residual, but it’s also what made them bad for us and the environment. Since the banning of Dursban there have been a few shorter residual materials labeled for home garden use against borers, but this necessitates multiple spray applications over the span of emergence.

With the entry of imidacloprid (found in Bayer Advanced 12-Month Tree & Shrub Insect Control) landscape professionals and home gardeners have been wondering if this systemic drench applied to the soil at the base of a tree could be effective controlling borers within a tree. Entomologists doubted it because most borers eat their way into the heartwood of the tree. The heartwood is non-living woody tissues that no longer transport water or nutrients. Once borers are in the heartwood, neither surface sprays applied to the bark or systemic materials applied to the soil will reach them.

However, flatheaded borers (a type of beetle) feed mostly in tissues right under the bark. Research has shown that an imidacloprid soil drench can provide reliable control of flatheaded borers (e.g. bronze birch borer) if applied early enough in the season. Colorado State University Extension entomologist, W. S. Cranshaw, indicates that imidacloprid “is not effective against any of the borers that develop into moths (e.g. clearwing borers, carpenterworms, Dioryctria spp.) nor against species that tunnel into the heartwood of the tree (e.g., roundheaded borers)” despite these borers being listed on the product label.

The best bet is to keep trees vigorous and healthy because most borers only attack stressed trees. Various causes of stress, such as drought, sunburned bark, or improper planting, weaken a tree and make it more vulnerable to borer attack. Planting and watering correctly can help prevent a borer attack. Trees also become stressed if they’re planted in soils or sites where they aren’t well adapted, such as planting a Japanese maple with exposure to hot full sun and wind.

The best bet is to keep trees healthy before borers “belly up.”

Published: 10/31/2009 11:52 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Forget pretty spring flowers, give me red, orange and yellow autumn leaves. Always entranced with the bright fall colors of trees and shrubs, I took a little time the other day to drive around and view the glorious hues of autumn.

One plant that always catches my eye is Burning Bush (Euonymus alatus). It’s bright red fall color is unmistakable. For just that reason, this shrub has been a staple of many landscapes. I can remember a hedge of Burning Bush on my college campus. It was huge. The species form of Burning Bush grows from 15 to 20 feet tall. Of course, most gardeners have planted Compact Burning Bush (Euonymus alatus ‘Compactus’), sometimes misleadingly called “Dwarf Burning Bush.” It is smaller than the species, ONLY growing to a height of 8 to 10 feet.

Because of their still rather large size, Compact Burning Bush shrubs are frequently sheared into ball, oval or square shapes. This is understandable, but unfortunate because the shrub has a very attractive rounded habit with a layered horizontal branching habit. This is lost when sheared to restrain its size.

If you like the color and habit of this shrub like I do, I would recommend looking for cultivars that are even smaller. One of these, ‘Odom’, also known as ‘Little Moses’, only grows to a height of three feet. This little guy has great red fall color, plus it holds onto its leaves a little longer in the fall.

Another diminutive Burning Bush is ‘Rudy Haag’ that grows very slowly to a height of 3 to 4 feet. It’s touted for its small size, dense mounded habit, and pink to red fall color. Within the nursery industry it’s also valued because it’s nearly seedless.

Burning Bush has become invasive in parts of the eastern US. It’s even been banned in Massachusetts and named as an invasive plant in Connecticut. Why the concern? Seeds from the fruit have been spread far and wide in the northeast by birds. “Planted” by birds, the shrubs have spread from landscapes and highway medians to the native forests where they have prospered, displacing native understory shrubs and wildflowers. While the spread of Burning Bush isn’t a worry in our area, the threat of invasive plants forcing out native growth should be of concern to all of us.

Recent research has shown that ’Compactus’ is a prolific seed producer. ‘Compactus’ and ‘Rudy Haag’ produced an average of 1238 and 12 seeds per plant, respectively. This was across a span of three years and over two growing sites. ” With very limited seed production, ‘Rudy Haag’ is much less of an invasive threat.

While sightseeing in the area, I noted many gorgeous trees and shrubs with excellent fall color. There were some spectacular maples along Jadwin in Richland. It was hard to make a definite identification while driving by, but they were most likely red maples or red maple hybrids.

Red maples (Acer rubrum) are well known for their beautiful fall color potential and there are a number of named cultivars. ‘October Glory’ is one very popular red maple cultivar with red to burgundy leaves in the fall. ‘Red Sunset’ tends to develop its orange to red fall color earlier than ‘October Glory’. ‘Autumn Blaze’ is a hybrid of red maple (Acer rubrum) and silver maple (Acer saccharinum). It has amazing fiery orange-red fall color, plus it’s a fast growing shade tree.

There are also other shrubs that can lend various hues of red ,orange, and yellow to the fall landscape. This includes Ninebark (Physocarpus opulifolius), Tiger Eyes Sumac (Rhus typhina ‘Tiger Eyes’), Amur Maple (Acer ginnala), Paperbark Maple (Acer griseum), and Dwarf American Cranberry Bush (Viburnum trilobum ‘Nanum’).

We may not have the spectacular fall color of the Northeast, but if you drive around the Tri-Cities you’ll see some outstanding plants in their fall glory.

Published: 10/24/2009 11:31 AM

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