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GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published July 3, 2016

It is simple, I grow flowers in my garden because they are pretty and colorful. It is very disappointing when insects damage or destroy these blossoms. Here are three dastardly pests that are significantly impairing beautiful blooms in my garden.
Thrips: Western flower thrips cause damage to roses and a variety of other flowering perennials. Thrips are very tiny, straw-colored insects that feed on flower petals, often before the buds even open. They use their rasping mouths to scrape at plant tissues and suck up the liquids that ooze out. Their feeding causes streaks and blotches on the petals. If damage is severe, the flower buds may fail to open.
Thrips are difficult to control because their populations build up very quickly. Prune off and dispose of badly infested flowers and buds. Eliminate plant litter and weeds in and around the garden. Avoid using pesticides that kill thrips predators, like lady beetles and lacewings, or that harm bees visiting the flowers. If you decide to apply an insecticide, apply it directly the buds and blooms. Repeat applications are likely to be needed. For effective insecticides, go to:
Tobacco Budworm: The tobacco budworm is devouring all the buds on my petunias, including my beloved Wave petunias, before they even have a chance to open. Aargh! The few flowers that are able to open, are riddled with holes. The adult of the tobacco budworm is an unremarkable greenish-brown moth about ¾ inch long. Like many moths, it is nocturnal, flying, mating, and laying eggs at night starting in late spring to early summer.
On petunias the moths typically lay their eggs on the leaves, but on geraniums they deposit them directly on the flower bud clusters. As soon as the eggs hatch, the little larvae immediately get to work eating flower buds. They will also eat holes in leaves, especially when there are not many flower buds left. Along with the obvious holes in flower petals, buds, and leaves, they deposit their telltale small black frass (poop) on the leaves.
The larvae are hard to detect because young larvae are yellowish-green in color and blend in well with the foliage. More mature larvae vary in color from green to brown, tan, or purple. During the day, the larvae tend to hide in the soil at the base of the plant and then venture out at dusk to feed. When using hand picking for control, look for them at dusk.
As their name infers tobacco budworm is a pest of tobacco, but it also feeds on many other hosts, such as roses, snapdragon, zinnia, verbena, chrysanthemum, marigold, and sunflower. However, its preferred hosts are petunias and geraniums.
Sunflower Moth: The larvae of the sunflower moth also attacks garden flowers. Its hosts are sunflowers and other members of the same family such as daisies, zinnia, coneflower, and cosmos. The larvae of the sunflower moth feed on the flower centers, eating the developing seeds and leaving webbing and frass .
Most home garden insecticides are ineffective against both the tobacco budworm and the sunflower moth. For effective insecticides go to:
When using insecticides for control of tobacco budworms, apply them as soon as feeding damage is noticed. For sunflower moths, apply them when the flowers start to bloom.
I do not like using insecticides in my garden, especially on flowers that are visited by bees and other pollinating insects. As a result, I have switched to plants planted for the colorful foliage, like coleus and sweet potato, but I just cannot give up my petunias!


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

The brown marmorated stink bug that has been plaguing the eastern part of the US damaging crops and invading buildings, but the stink bug that’s a problem for some area gardeners is a green stink bug. It’s feeding is causing yellowish to whitish cloudy spots all over tomatoes infested with stink bugs. Just beneath the skin of a ‘cloudy spot’ are clusters hardened white spongy cells. While still edible ,this makes the fruit difficult to peel and impairs their eating quality.

This is the time of year stink bugs residing in nearby weeds move to the garden to pierce ripening tomatoes. Scientists disagree exactly what causes the spots, but generally it’s believed that they inject a toxin into the fruit when they pierce it for its juices. There are a variety of different stink bugs that can cause this damage, but the one gardeners are bringing to me are bright green ‘Say’ stink bugs. These shield-shaped bugs are about .5 inch in length with orange spots at the base of the triangular back. The nymphs or young stink bugs are blackish in color. There are also brown stink bugs that can be found in the garden.

According to University of Utah bug experts, one stink bug per plant could cause 5-10% damage. That means that it doesn’t take excessive amounts of stink bugs to cause significant injury to garden tomatoes. If suspect you have a stink bug problem, the Utah expert indicated that you can find the culprits ‘by vigorously shaking the plant and examining the dirt beneath for fallen insects.’ Another hint that stink bugs are present is the brown liquid frass (yuck) that they leave behind as dried spots on the leaves and fruit where they’ve been feeding.

If you have a stink bug problem, control will not be easy. That’s because stink bugs don’t reside in the garden, but in weedy areas nearby, such as fence rows and ditches. Control involves eliminating weeds to prevent their overwintering and keeping weeds down during the gardening season. Potential overwintering hosts include Russia thistle, plantain, mullein, mustards, mallow, dock, blackberries, legumes, as well as other weeds.

In addition to good weed management, pesticides can be utilized for control but you should not only spray the vegetable garden, but also weedy areas that may be serving as stink bug havens. If you’re gardening organically, try using insecticidal soap sprays. Keep in mind that the soap sprays only affects the bugs to which it directly applied, so you’ll need to reapply soaps regularly.

There are also garden insecticides containing bifenthrin, permethrin, cyfluthrin, imidacloprid, or carbaryl that are effective against stink bugs. Be sure to find a product labeled for use in the vegetable garden, particularly tomatoes. If you use them on other vegetables or fruits be sure that they’re also listed on the label.

Some of these garden insecticides are highly toxic to bees. Be sure to follow all label directions and take the precautions needed to protect bees, wildlife, and yourself. Always check the label to find out how many days after spraying you must wait before you can safely harvest and consume (or preserve) the fruit. This may be labeled as ‘days to harvest’ or ‘pre-harvest interval’.

Finally, to answer another question that may be on your mind… yes, stink bugs do really stink. As a defense mechanism they have small glands on their body that emit a foul smelling liquid when threatened or mistreated. Eat one in a raspberry or hand squash them in the garden, and you’ll find out that they come by their name honestly.

Published: 8/3/2012 1:42 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Several weeks ago we talked about two relatively new pesticides that are available to home gardeners for controlling pests out in the garden. Today, let’s tackle two more pesticides commonly available to home gardeners.

PYRETHRUM, PYRETHRIN, PYRETHROID: Pyrethroids are synthetic chemicals that were created to have a structure and mode of action similar to naturally occurring chemicals known as pyrethrins. Pyrethrum is a plant-based or botanical pesticide made from the dried flowers of the pyrethrum daisy (Chrysanthemum cinerariaefolium) and some other closely related Chrysanthemum species. Pyrethrins are the naturally occurring chemicals found in these flowers that have insecticidal properties.

Pyrethrins are fast acting contact poisons that attack the nervous system of certain insects leaving them paralyzed. Some of these insects are able to recover from this knock-down effect by detoxifying the chemicals in their system. That’s why most pyrethrin-based products contain a synergist compound, usually piperonyl butoxide (PBO), that interferes with an insect’s ability to break down the pyrethrins. With the addition of synergists to pyrethrins, they act both as stomach poisons and on contact to kill insects.

While considered “natural,” pyrethrins are highly toxic to fish, bees, and other beneficial insects so care must be taken when using them. However, they are quickly degraded in the environment by UV light and have little residual activity. Because of their short residual activity, pyrethrins often need to be applied more than once to control a pest problem.

Now let’s move onto pyrethroids, manmade pyrethrin synthetic derivatives. While the chemical structure of pyrethroids are similar to pyrethrins, they have been created to be longer lasting in the environment. Where pyrethrins may degrade and lose their effectiveness in 12 hours, some of the pyrethroids will last 30 days or more. Because of their residual activity and their chemistry, they’re more effective in controlling a variety of pests, working both as contact and stomach poisons. The newest pyrethroids tend to have a much longer residual and are more effective on chewing and crawling insects. You’ll note on the labels that pyrethroid products are also toxic to fish, bees, and other insects.

A number of pyrethroids can be found in todays’ home and garden pest control products. These include allethrin, bifenthrin, cyfluthrin, cypermethrin, deltamethrin, esfenvalerate, imiprothrin, lambda-cyhalothrin, permethrin, prallethrin, sumithrin, tau-fluvalinate, and tetramethrin, with permethrin currently dominating the market place.

INSECTICIDAL SOAP: Insecticidal soap is frequently recommended as a low toxicity and environmentally friendly pesticide for control of soft-bodied insects and mites. Insecticidal soaps are soaps (potassium fatty acids) that have been formulated for use on plants. They work on contact via disruption of the structure and permeability of an insect’s membranes. They’re only effective on mites and soft-bodied insects (aphids, mealybugs, adelgids, true bugs, leafhoppers, mealybugs, thrips, and whiteflies) to which they’re directly applied. There is no residual activity, so soaps ONLY control those susceptible pests to which they’re directly applied. If aphids are protected by leaves that have become curled and distorted by their feeding, soap sprays will not be effective.

You may find various home “recipes” for making your own insecticidal soap using dishwashing liquid or other “soaps.” Many of these materials are actually detergents and may injure plants. Insecticidal soaps have been formulated to be safe on most garden and landscape plants, although certain plants are sensitive to soap sprays. Check the label, but generally insecticidal soaps should not be used on horse chestnut, mountain ash, hawthorn, cherry, Japanese maple, sweet gum, lantana, bleeding heart, azalea, begonia, impatiens, nasturtium, or succulents.

Soaps should not be applied to plants that are under drought stress or when temperatures are high, above 90 degrees Fahrenheit. Spray in the cool of the morning or evening. Soft plant growth in the spring may be sensitive to injury from soap sprays, so try to wait to treat plants until after the new growth has hardened. If you don’t purchase a RTU (Ready-To-Use) insecticidal soap and will be mixing it yourself, use distilled or softened water. Hard water decreases the effectiveness of a soap spray. When applying the soaps, be sure to cover both the tops and bottoms of leaves. Soaps are most effective with thorough coverage.

Published: 6/14/2008 1:58 PM


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

This year many gardeners are facing the growing season with fear and trepidation. Diazinon, the old tried-and-true chemical that they used for many years to control insect pests is no longer available to gardeners. As an organophosphate insecticide, there were concerns about the health risks, especially to children, that diazinon posed. With the demise of this familiar chemical, gardeners are wondering what they can find to help them manage destructive pests in their garden.

One group of chemicals showing up in many home garden insect control products are the pyrethroids. These are man-made synthetic pesticides that are chemically similar to the natural pesticide pyrethrum. Pyrethrum is considered a natural chemical suitable for use by organic gardeners. It’s a natural chemical that comes from Dendranthemum cinerariaefolium, which is grown mostly in parts of Africa and Ecuador.

Pyrethrum is one of the most widely used organic pesticides. It’s valued for it’s quick knock-down effect on many insects. However, because this knockdown doesn’t always mean the insect is ‘down for the count,’ many of the pyrethrum products have a synergist (usually piperonyl butoxide known as PBO) added to them which magnifies the effect of the pyrethrum and leads to insect death.

Since pyrethrum has a very short residual, its use is primarily as a contact poison. This means the material must contact with the insect to be effective. It doesn’t kill via ingestion when the insects eat treated plant tissues. Because it has extremely short residual activity, many gardeners have not found pyrethrum to be a particularly effective tool in their attempts to manage garden pests.

Pyrethroids are synthetic chemicals that have been created to chemically imitate natural pyrethrum. The big difference between pyrethrum and pyrethroids is that these synthetic materials have been altered to provide better control of insects and longer residual activity.

While over 1000 of the pyrethroid synthetics have been created, only a handful are typically found in home and garden products. Resmethrin and allethrin have been available for a number of years and are typically found in short residual sprays for control of household pests, including wasps, hornets, flying insects, spiders, and mosquitoes. Permethrin can be found in sprays and granules sold for control of chewing and crawling insects.

The newest pyrethroids on the market are those with a longer residual and greater effectiveness in killing chewing and crawling insects. It is this group that is filling in part of the gap left by the withdrawal of diazinon. These newest pyrethroids include sfenvalerate, cyfluthrin, bifenthrin, deltamethrin, lambda-cyhalothrin, tralomethrin, cypermethrin, and others.

As with any pesticide product, you should always read and follow all the directions and precautions on the label. One thing to note is that some people using pyrethroids and pyrethrum containing products may have an allergic skin reaction to the materials. If you’re allergic to members of the chrysanthemum family, it’s probably best not to expose yourself to them via application of pyrethroid products. Another precaution that should be noted in our region is to avoid use of products containing the synergist PBO when the temperature is above 90 degrees, as plant damage can occur. The final precaution regarding their use is toxicity. While these products are not highly toxic to mammals, they are highly toxic to fish. Don’t spray them around bodies of water where fish reside.

Another type of chemical that will probably see increased use by gardeners are horticultural oils. The use of oil to control pests is not new. Different types of oils have been used for many years to control certain insect pests on plants. In recent history, horticultural oils were used primarily on dormant woody plants to control overwintering pests and were applied just before plants and insects started to grow in the spring. These oils were commonly called ‘dormant oils.’

A new ‘breed’ of horticultural oils are now being used for pest control both in the dormant season and also later in the season. These oils are highly refined petroleum oils which have had various chemical compounds and impurities removed. These ‘superior horticultural oils’ are now safe enough to use on many woody ornamentals and garden plants during the growing season.

Back in the ‘old’ days, the less highly refined horticultural oils used for pest control could only be applied to dormant woody plants to control overwintering pests, such as aphids and mites. The new horticultural oils can also be used on dormant plants in the same manner, but at a lighter rate they can be used on plants during the spring and summer.

Oils kill target insects by suffocation, the oils block their air holes (called spiracles) through which they breath. Scientists also believe they may also act as poisons that interfere with the insect’s normal metabolism or prevents its feeding. Oils are primarily useful against soft-bodied pests such as adelgids, aphids, eriophyid mites, spider mites, leafhoppers, scale insects, whiteflies, plant bugs, and even some caterpillars.

One concern about using oils on plants is the potential damage they can cause to plants if not used correctly. There is less hazard of injury to plants with the newest horticultural oils because they have been highly refined. These new oils can be used safely on a number of plants including many woody ornamentals, fruit trees, bedding plants, vegetables, and herbaceous plants. However, plant damage can occur if not used correctly.

Injury to plants can happen if too much oil is applied; if plants are under drought stress; if temperatures are above 90 degrees; if temperatures are below 45 degrees; if the relative humidity is over 90 per cent for 48 hours (not likely to happen here); if used too often; if the dormant rate is used on plants that are not fully dormant in the fall; and if used in combination with sulfur containing materials or applied soon after sulfur has been applied.

Certain plants are sensitive to oils and damage can occur, even if they are applied correctly. The pesticide label will indicate to which plants the oils should not be applied, but plants that are generally known to be sensitive include black walnut, hickory, cryptomeria, spruce, Douglas-fir, juniper, cedar, maple, redbud, and smoke tree.

Gardeners should not fear garden disaster without diazinon. As gardeners start to utilize these new substitutes, they should be able to effectively manage pests… as long as they understand the correct use of the materials and what types of pests they’ll control. Good luck!

Published: 5/14/2005 1:41 PM


written by Marianne C. Ophardt WSU Extension Faculty for the Tri-City Herald, Kennewick, WA Usually we have several more weeks of cool weather before our spring gardening chores have us all bustling about, but spring has arrived early! It’s time to get our ‘crabgrass preventers’ on lawns. It’s also time to be thinking about what we’re going to use for pest control in our yards and gardens now that diazinon is gone. With a severe drought declared for this year, we need to make some choices in our landscape. Lawns: With this early spring weather, comes the need to apply crabgrass preventers, also known as pre-emergent herbicides, to our lawns. These chemicals (benefin, trifluralin, and pendimethalin) prevent the germination of crabgrass seed. They’re applied to lawns when the soil temperature reach about 50 to 55 degrees. That usually happens when forsythia starts dropping its flowers and redbud trees are in full bloom. (Forsythia is the bright yellow-flowering shrub that’s in bloom right now.) To be effective, you must apply the materials before the crabgrass seeds begin to germinate and grow. Germination starts when the soil reaches a temperature of about 60 degrees and usually continues for several weeks. Because of our early spring weather, you may need to consider a second application of crabgrass preventer late in the spring. This is because some of the materials used may dissipate before the end of this long germination period brought on by our very early balmy weather. Some chemicals, such as benefin, have shorter periods of residual activity, others last longer. Check your label to see how long the product should be effective. Crabgrass preventers are useful chemical tools, but there are lawn care practices that can go a long way in helping control a crabgrass problem . Crabgrass needs light to germinate. A dense, healthy lawn discourages crabgrass. The best way is to keep your lawn thick and healthy is through sound management practices, including proper mowing, irrigating, and fertilizing. Finally, before you use a ‘preventer’ chemical make sure the offending weedy grass is actually crabgrass. Many local gardeners apply these chemicals at the right time and then complain about their ineffectiveness. This could be because the material wasn’t applied uniformly or at the correct rate, but it could also be that the ‘crabgrass’ wasn’t crabgrass at all. Frequently, home gardeners think they’re dealing with crabgrass, when they actually have a tough perennial weedy grass, Bermuda grass. This wiry, tough-to-control weedy grass is not effected at all by the preventer chemicals. To be sure you have a crabgrass problem, bring a sample of your problem grass to the Benton County WSU Extension Master Gardener Plant Clinic in Kennewick. No More Diazinon: Because there were concerns about long-term health hazards, especially to children , the use of diazinon by home gardeners has been canceled. As of the end of 2004, diazinon may no longer be sold to home gardeners… although gardeners may use up their existing supplies. That leaves home gardeners with very few materials for controlling of garden pests, especially chewing insects. There is still an older material, malathion, but many gardeners don’t like it because of it’s odor. Carbaryl, also known as Sevin, is also still available for control of chewing insects. Relatively new on the market are spinosad products. Spinosad is a ‘biorational’ pesticide that is derived from metabolites the result from the fermentation process of a particular soil bacterium. Spinosad mainly kills insects through ingestion… eating treated plant tissues. That means it will control chewing insects, such as caterpillars, leaf beetles, and leafminers but it won’t control sucking insects, such as aphids. It kills the insects by overexciting their nervous systems. It is considered an organic pesticide and has limited impact on certain beneficial insects. Spinosad is available to home gardeners in Monterey Garden Insect Spray. Several local specialty farm and garden stores carry it. It’s also available as Bull’s-eye Bioinsecticide through mail order from Spinosad has no offensive odor and it’s of low toxicity to mammals, but it is highly toxic to bees. It can be used on ornamental plants, most tree fruit, lawns, and vegetables for control of caterpillars (worms), thrips, and leaf miners. It does not have a long residual and several re-applications will be needed with certain pests. Drought Tip 2: Making Choices and Getting Ready for Drought Now Some areas of our region will have only a small percentage of the normal amounts of irrigation water available to them this growing season. Gardeners facing these types of restrictions will need to make some choices now about which plants to save and which plants to let go. If you will be getting very little irrigation water, decide now which parts of your landscape you will water regularly and which ones you won’t. Perhaps the most important part of your landscape are the trees. Trees increase in value as they grow older and bigger in size… and increase your property values. Trees should probably be the first in priority when watering this year. Next, would be well-established healthy shrubs that are contributing to the beauty and value of the landscape. Overgrown, pest-ridden, or poorly placed shrubs could be sacrificed. Perhaps next in the hierarchy would be garden areas with flowering perennials, especially those with special, expensive perennials that would be costly to replace. Lowest on the list would be annual bedding plants and vegetable gardens. These are annual plantings that have a relatively high water demand. You may want to forego these plantings for this year. Finally… many lawn grasses can survive with minimal water. Lawns can be allowed to go dormant (turn brown), but can survive the drought if watered two or three times during the growing season.

Published: 3/19/2005 1:45 PM



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