Washington State University Extension

Garden Tips

Archive for August 2011


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Everything seemed to be going so well in my flower garden after the cold wet spring and an unbelievably slow start to the season. Little did I know that my flowers, both annuals and perennials, were going be attacked by an army of small and stealthy caterpillars. It’s Armageddon in my garden!

The pest is the tobacco budworm. The adult is a greenish brown moth with a wingspan of 1.5 inches. At nightfall, the adult supposedly lays its eggs individually on flower buds. The eggs hatch into tiny larvae which eat their way inside of the buds. As they eat, the larvae grow bigger, doing more and more damage. They also tunnel into plant stems and feed on leaves.

My first hint of the attack came when I noticed that all my daisy-like flowers (coneflowers, zinnias, helianthus, and more) weren’t lasting very long. The flowers were fading fast after opening. I discovered the problem when I was deadheading the spent flowers. I noticed frass (insect excrement) in the flower centers and tore them apart to find little brownish, striped caterpillars. In large coneflowers, several larvae were busy chowing down. (Depending on its food source, the striped larvae will vary in color and can appear red, green or tan.)

The tobacco budworm doesn’t just attack daisy-like flowers, it wreaks havoc on a number of other types of garden flowers, especially geraniums, petunias, zinnias, and Nicotiana. Geranium is so commonly attacked that this pest’s alternate common name is geranium budworm. According to Whitney S. Cranshaw, Colorado State University Extension entomologist, it has become such a serious problem in some parts of the country that people have discontinued the use of geraniums and petunias in their gardens.

I first encountered the tobacco budworm several years ago when it attacked my petunias. It feeds on the petunia flower buds which then open up with big holes in the petals. I also noted damage on my zinnias and other gardeners complained about it attacking their geraniums.

From my personal encounters with the tobacco budworm, I know this pest is established in our area. However, few gardeners seem to recognize its presence or complain about its damage. Because of our relatively long growing season, it’s likely that there are at least two generations of the tobacco budworm here per year.

It has been thought that the budworm would not survive our cold winters, because it overwinters as a pupa in the top six inches of soil and is killed by temperatures below 20 degrees Fahrenheit. However, Cranshaw points out that ” warm soil microclimates, such as those found around the foundations of heated buildings, can allow many to survive. As a general rule, the number of overwintering tobacco budworms and the likelihood of problems are related to the severity of the previous winter.”

Because the budworm bores inside of buds and stems, it’s difficult to control with insecticides, plus it’s resistant to many pesticides. Cranshaw indicates that synthetic pyrethrins (such as permethrin, esfenvalerate, cyfluthrin, and bifenthrin) labeled for garden use are the most effective. Bacillus thuringiensis (Bt), an organic pesticide, will provide only minimal control.

Attacked by these sneaky destructive budworms, my garden flowers are losing the battle. I’m reluctant to join the fight and use pesticides, but if I want to have pretty flowers in my garden and pots I must.

Published: 8/6/2011 2:46 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

My vegetable garden is small, so the only veggies I grow are yellow crookneck squash and tomatoes, my two favorites. I rely on the local Farmer’s Markets for other fresh vegetables during the season. The reason for growing garden tomatoes is obvious to anyone who relishes fresh, vine-ripe tomatoes… taste. I grow crookneck squash for the same reason. Most of the summer squash I find at the grocery store or the markets is too big and not very tasty.

All of us know the tales of gardeners who try to unload their gigantic zucchinis on unsuspecting neighbors or those who make endless loaves of zucchini bread so they don’t waste their garden produce. Many folks don’t like any type of summer squash. That’s probably because all the squash they’ve ever tasted has been from mature and over-mature fruit.

Summer squash should be harvested when they’re small and immature. That’s when their flavor is the best. Harvest zucchini, cocozelle, yellow straight-neck, and crookneck squash when they’re quite small, about 6 inches in length and less than 2 inches in diameter. Patty pan and scallop squash are best when they’re about the size of a silver dollar up to 3 inches in diameter.

During summer heat, summer squash develop very quickly and can be ready to pick within several days of flowering, so frequent checking and harvesting is a must. To harvest summer squash, wear garden gloves and use garden shears or a sharp knife to cut the stems. The skin is very tender, so handle them carefully to avoid scratching it. For the best flavor, prepare and eat the squash right away. (I like them best grilled on the barbecue.)

If you harvest more than you can use immediately, wash the fruit with clean water, let dry, and place them in plastic bags in the refrigerator crisper drawer. Use them within two to three days.

Knowing when to harvest tomatoes for best flavor may not be as easy as you might think. Once a tomato blossom sets fruit, the tomato starts to develop. It will reach full size and maturity after a month or more. Once fully mature, the dark green fruit changes to a light green. After that it begins to soften and ripen, developing the color for that variety, such as red, yellow, or purple.

The ripening process depends on temperature and ethylene, a natural growth regulator produced by the plant. The best temperatures for tomato ripening are between 68 and 77 degrees Fahrenheit. The ripening process is slower when temperatures are lower than 68 degrees. When temperatures are above 90 degrees, the softening process speeds up, but fruit color development slows down and may even stop when the weather is very hot.

Sweet vine ripened tomatoes are the goal of every gardener, but during hot weather it may be prudent to regularly harvest mature tomatoes that are beginning to show some color and ripen the fruit indoors at temperatures of 72 to 75 degrees. Left outdoors to ripen in hot weather, they may fail to develop good flavor and color. Tomatoes don’t need sunlight to ripen.

Harvesting more squash or tomatoes than your family can use? Don’t forget that local food banks welcome your extra produce. However, save the green zucchini monsters that have hidden from you and recycle them in the compost pile.

Published: 8/13/2011 2:43 PM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Last year one of my columns was titled “Tenacity Key to Controlling Bermudagrass in Landscape .” Little did I know that a newly introduced herbicide has the name “Tenacity.” Unfortunately, this new herbicide isn’t the key to Bermudagrass control, but it does provide control for a number of other broadleaf and grassy lawn weeds.

The active ingredient in Tenacity is mesotrione produced by Syngenta who says the chemical is based on a naturally occurring compound produced by the bottlebrush plant (Callistemon citrinis) that naturally inhibits the formation of carotenoids in susceptible plant species.

Why the bottlebrush plant? Syngenta recounts that one of their scientists noticed that there were fewer weeds growing under his bottlebrush plant, fewer than could be explained by shading alone. This scientist surmised that the plant was probably producing allelochemicals to suppress weed competition. Syngenta investigated and found that bottlebrush does indeed produce allelochemicals. Based on the naturally produced chemicals they discovered, Syngenta was able to synthesize mesotrione for use as a selective lawn herbicide.

How does it work? Mesotrione inhibits a plant enzyme that’s needed for photosynthesis and prevents the formation of carotenoids in susceptible plant species. Lacking essential carotenoids, cell membranes and chlorphyll are destroyed when exposed to light and photosynthetic by-products.

Mesotrione is a systemic herbicide that quickly moves throughout the weedy plants after application. Once it disrupts photosynthesis, plant leaves turn white and within several weeks the plant dies. Not only does Tenacity provide control of at least 46 lawn weeds, including some invasive grasses, it has both pre-emergence and post-emergence activity. It’s safe to use on lawns comprised of Kentucky bluegrass, perennial ryegrass, tall fescue, or fine fescue.

Listen to this… it can be used to control creeping bentgrass, crabgrass, foxtail, goosegrass, nutsedge, and barnyard grass in lawns. It will also provide some pre-emergence suppression of annual bluegrass. Many common and some particularly tough-to-manage broadleaf weeds are also controlled, including dandelion, oxalis, ground ivy, henbit, clover, violets, purslane, lambsquarter, and plantain.

Another nice thing about Tenacity is that unlike many other pre and post-emergent herbicides it can be applied when seeding a new lawn or renovating an old one to prevent weed seed germination.

Other things you should know about Tenacity.

1. Because of possible carryover, you should not use the clippings from a treated lawn as a mulch in the vegetable and flower gardens or beneath trees and shrubs.

2. You should not grow anything other than grass in treated areas for 18 months or more.

3. An application of Tenacity may cause your lawn to turn whitish for several weeks, but the healthy green appearance will return in several weeks.

4. EPA has given Tenacity a registration of reduced-risk status because of its unique mode of action, low use rates, and low impact on human health.

One more thing you need to know is that an eight ounce bottle of Tenacity costs about $80 to $85 via mail-order, but the bottle is enough to treat an acre or more of lawn. This new herbicide is pricey, but if it does its job it may be worth it.

Published: 10/11/2012 11:24 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

I was talking with a Master Gardener the other day about the root weevil problem in his little blueberry patch. Root weevils are a group of specialized brown or black snout-nosed beetles that attack a variety of ornamental plants.

Root weevil damage is characterized by notching of plant leaf edges. (They don’t eat holes in leaves.) Generally, this notching is a cosmetic concern and seldom does significant injury to a plant, but when their numbers are extremely large they can damage plants.

The weevil’s white C-shaped, legless larvae develop in the soil, feeding on the plant roots, root hairs, and the root crown at the base of the stems. The larvae can cause serious damage in potted nursery plants and in very sandy soil.

Most gardeners only note the notching damage and seldom see the actual weevil adults. That’s because during the day the adult weevils hide out in the soil and debris at the base of plants. After dark they come out and climb up the plants to feed on the leaves.

With the demise of many harsh garden pesticides, root weevil control has been particularly difficult to achieve, especially on food producing plants like the blueberries. That’s why the Master Gardener has been trying to collect them off his plants on a nightly basis to reduce their numbers.

Because adult root weevils will drop from the plant and “play dead” if disturbed at night when feeding, he was able to spread a cloth under his plants to collect the adults. After dark he went out at midnight and shook the plants. However, he encountered a problem. No weevils dropped off at that time. However, when he went out at 2:30 a.m. he was able to collect 15 per plant. He did this for several nights in a row, collecting about 15 weevils each time. He stopped when the number dropped to just one or two.

Curious about root weevil behavior, I called WSU Extension’s resident root weevil expert, Sharon J. Collman. She has done extensive research on these creatures for her PhD thesis.

Collman found 14 different species of root weevils in the Pacific Northwest during her 450 nocturnal collections of weevils. The black vine weevil (Otiorhynchus sulcatus), the obscure root weevil (Sciopithes obscurus) and the strawberry root weevil (Otiorhynchus ovatus) are the most commonly known root weevils that she found. She also found that the lilac or privet weevil (Otiorhynchus meridionalis) was the most common and often dominant species in eastern WA gardens and landscapes.

Collman notes that research on the effectiveness of specific insecticides for control of root weevil adults is limited, with 60 per cent of the studies researching the control of black vine weevil and only a limited number of studies (0 to 20 per cent) looking at the other 13 species found in our region. Some studies indicated that pesticide efficacy differed from species to species. This points out that what works in one region, may not work in another.

WSU recommends using acephate, cyfluthrin, neem oil, befenthrin, and azadiractin to control root weevils on ornamental plants like lilac and rhododendron. They recommend malathion for control on berries, such as blueberries. However, depending on the actual type of root weevil doing the damage, you may find these are not extremely effective. It may come down to setting the alarm clock and going out in the dead of night to shake the weevils from your plants.

Published: 10/11/2012 11:24 AM



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