Natter’s Notes

Fertilizing Seasonal Vegetables and Flowers

Jean R. Natter, OSU Master Gardener

When it comes to fertilizing plants, common myths may risk your plants’ health.  The general guideline is to start early and supplement as the season proceeds. So, let’s look at the facts, while focusing on growing annual flowers and vegetables.

Synthetic or organic?

It’s important to know that many brands and forms of fertilizer work well. Whatever your choice, organic or synthetic, liquid or solid, the goal is to produce abundant yields of flowers and/or edibles. It’s also possible to use a combination of organic and synthetic. For instance, you might plant a cover crop, then follow with synthetic fertilizers at the appropriate times. (See Cover Crops for Home Gardens; FS 304;

In order to obtain the same end result, synthetic products are less costly than organics, are applied in small amounts, and act rapidly. Organics cost more, in part, because they require larger amounts as well as considerable labor to haul and apply. Then, too, organics react relatively slowly because they rely on soil organisms to release the fertilizer elements. Perhaps the greatest value of the bulky organics (manure), is that a small percentage of fertilizer elements remains to be released during subsequent years. Thus, avoid overloading the soil by applying the full amount of manure for 1 to 3 years, then apply a smaller amount during successive years. (See EC 1503, page 7.)

Soil tests

A professional soil test is useful before beginning a new garden to identify possible excesses and deficiencies in the soil. Then, when repeated every several years, the test will note changes and suggest adjustments in fertilizer applications. Fall is a good time for a test because lime and possibly other remedies can be applied in a timely manner.

Here, in the metro counties, we typically suggest the nearby A&L Soil Lab, 503-968-9225. Call them to ask how to sample and how to deliver the soil. Request a general test, with recommendations, for a home garden in which you will grow annual vegetables, or whatever else you are interested in, perhaps lawn.

Fertilizing seasonal plants in the garden versus in pots

When it comes to fertilizer deficiencies in our region with its clay-based soils, the most common in home gardens is nitrogen. (Nitrogen deficiency is revealed in pale and/or stunted growth; oldest leaves turn yellow, then dry and may drop; new tip growth is dark green.)  So, for the most part, you can forget about using any of those various fancy deficiency charts when growing seasonal plants in the garden. In most instances, a general fertilizer with nitrogen (N), phosphorus (P), and potassium (K) will do the job for seasonal flowers or vegetables, presuming, of course, that the plants receive appropriate amounts of light and water for their kind.

Growing in containers is where things may become complicated. Fill them with a commercially-prepared potting mix because the coarse components will allow good drainage in the shallow depth available in most pots as long as it has drain holes. (Avoid adding coarse stuff in the bottom because, contrary to popular opinion, it impedes drainage.) Find a potting mix that works for you and your watering habits, then always use the same stuff in your containers.

It’s worth knowing that commercial potting mixes enriched with a bit of fertilizer will need additional fertilizer if your seasonal plants are expected to achieve the expected abundant yields. Always use a general purpose product designed for container-grown plants.

Wherever a seasonal plant is growing, in the ground or a pot, don’t bother adding a high phosphorus fertilizer to encourage bloom. A plant absorbs what it needs when it needs it. More important yet, adequate phosphorus must be available in the first quarter of the plant’s life.

Starting seasonal flowers and vegetables from seed

If you seed directly into the garden, begin by digging to the depth of a garden fork, remove weeds and debris, mix in several inches of compost, then level the soil. Next, rake in a starter dose of granular fertilizer, then seed and, finally, settle the soil by gently watering.

As soon as the cotyledons (seedling leaves) change position from vertical to horizontal, apply a liquid fertilizer at quarter strength. Follow up with a side-dressing at about 4 weeks. (Or follow the package directions!)

Similarly, when seeding into a container, fill it with slightly moist potting mix, seed, then water lightly to settle the seed and potting mix. When the cotyledons become horizontal, apply a liquid fertilizer at quarter strength.

Set your transplants, either home-grown or purchased, into their final growing place when they are several inches tall, then water with quarter-strength fertilizer to settle the soil. It won’t be long until you can start harvesting.

Useful Resources

Growing Your Own (EM9027) provides a rapid overview especially useful for gardeners, including those new to our region. Particularly helpful is the chart of planting dates for vegetables. (We’re in Region 2.)

Soils and Fertilizers (chapter 2 in Sustainable Gardening, the MG handbook)

A Guide to Collecting Soil Samples for Farms and Gardens

Fertilizing Your Garden (PNW 1503) includes the use of wood ashes.

Fertilizing with Biosolids (PNW 508)

PDF Version:
Fertilizing Seasonal Vegetables and Flowers

Natter’s Notes

Helpful Books & Websites

Jean R. Natter, OSU Master Gardener

Research-based information underlies everything Master Gardeners do. But it’s challenging to keep up with all that when you’re scrambling to know where the information is. When you’re searching online for data, adding “site:edu” (without the quote marks) will limit the results list to information from educational institutions. Unfortunately, “site:edu” doesn’t guarantee accuracy, because people aren’t perfect. (Believe it or not, mistakes happen.)

Right now, you may be wondering who, or what, can you believe? Well, to increase the likelihood of passing on accurate information, always review and compare at least 3 of the search responses. If disparities exist, continue searching and/or ask someone who may be able to provide additional insights. Your goal is a “Teachable Moment” during which you accurately inform the public. No home remedies, even if one was suggested in a university publication.

To begin your research, realize that each metro MG Office has a list of pre-approved resources in the “Master Gardener Office Information” binder under Tab L, Helpful Books and Websites. Begin with the list’s Table of contents. Each section generally lists books first, then websites. Most cited books are in each MG Office.

Following is a brief sample from the final page: Five very common, annoyingly weedy plants that tend to run rampant in the northwest. Some have been declared invasive, others are on a watch list.

Arum, or Lords and Ladies (Arum italicum) Herbaceous perennial; green leaves marked w/ white; deep fleshy root w/ offsets; prolific seeder

Lesser Celandine (Fig buttercup; Ranunculus ficaria; formerly Ficaria vicaria; Ficaria verna)

Pokeweed (Phytolacca americana) An escaped shrubby herbaceous perennial with poisonous berries

Spurge laurel (Daphne laureola) A woody Daphne escapee; seeds freely in northwest woodlands

Tree of Heaven (Ailanthus altissima) Large, rapid-growing, a profuse seeder, with many root sprouts

Tree of Heaven

PDF Version:
Helpful Books and Websites

Natter’s Notes

A New Spider; Trellis Rust

Jean R. Natter, OSU Master Gardener

A new spider in Oregon: The Brown Widow Spider

The Brown Widow Spider (Latrodectus geometricus) recently identified (October 2018) in Oregon City, OR, is a tropical species unlikely to survive outdoors in the northwest. The hourglass mark on the ventral abdomen is orange instead of red as on the Black Widow (L. hesperus). (

Almost everybody loves to hate spiders. Especially during the late summer and fall, when the males are dashing around the house searching for females.

Well, let me introduce the Brown Widow Spider, Latrodectus geometricus, a relative of the black widow. Now, people have another spider to worry about. (The western black widow, L. hesperus, is scarce in western Oregon, more abundant in the south and east sections.)

A first-ever record for Oregon, the brown widow was found in Oregon City earlier this year. It resembles an adult-sized version of an immature black widow, a variable combination of off-white, brown, tan and black. It can be challenging to differentiate between the 2 species until they’re more than half-grown. Finding an egg sac makes it easier; the brown widow’s is “spiky” whereas the black widow’s is smooth.

Resources: Spiders

– Oregon Spider Facts, a livestream video, with the main topic the recently identified Brown Widow Spider (ODA 2018-10-01; Entomologists Jim LaBonte and Josh Vlach, ODA Insect Pest Prevention and Management Program;

– “How to Identify the Brown Widow Spider” (R. Vetter; UC Riverside) –

– “Brown Widow Spider: Facts from Entomologist Josh Vlach” (video; 2 min 35 sec;

– “Oregon Spiders” contains basic information and numerous links –

– Overview of potentially venomous spiders in Washington (and Oregon):

– “How to Identify the Hobo Spider” and the giant house spider (Eratigena atrica) – The final verification step: Examine the male palps (p.7) or the female epigyne (p.9).

Trellis Rust on Pear

Trellis Rust on pear was submitted to the Clackamas County MG office last month (October 2018). To date, reported cases in the metro counties have been mild, with the unusual eruptions (“acorns”) on the leaf reverse of only a few leaves on each infected tree. (Client image)

An alert client submitted images of Trellis Rust on 3 y.o. pear trees to the Clackamas County MG office last month (October 2018), a disease first identified in Oregon during 2016. Signs, symptoms, and the alternate host (juniper) are quite different from those of the more common Pacific Coast Pear Rust (alternate host incense cedar).

The MGs reported the infection to Jay Pscheidt, the OSU Plant Pathologist. Here’s his response:

Looks like we have this disease on pear in Benton, Marion, Clackamas and Multnomah counties. I have not heard of any other places. No one has made mention of it on Juniper which is interesting in itself.

From our experience this year in the Corvallis area it has not been too severe on pear. A few leaves on a few trees. In the home landscape, leaf removal seems a viable option for the moment.

I suspect chemical management may help but timing is everything. Bonide Fruit Tree and Plant Guard RTS is registered for pear but also contains an insecticide in addition to a group 7 + 11 fungicide. It should have some activity on both scab and rust. But we don’t need to be spraying pear trees now as the spores are heading to the juniper alternate host. Infuse Systemic Disease Control is registered for juniper and may have some activity to prevent infection of rust. In other words, spray pears in the spring and junipers in the fall if you want to use chemical protection.

Separation of the hosts will be the best method.

Resources: Trellis Rust on Pear

– Trellis Rust (PNW Handbook; –

– Pacific Coast Pear Rust (PNW Handbook –

– “Pear Trellis rust, a new disease” (Natters Notes; 2017-10 –

– “Pear Trees: Rust, times 2” (Natters Notes; 2018-06 –

PDF Version:

Natter’s Notes Spiders and Trellis Rust PDF

Natter’s Notes 

When Pesticides Change

Jean R. Natter, OSU Master Gardener

You know the rule about pesticides: “Read and follow label directions.”

Well, that catchy little phrase has become more critical than ever. Several popular home-use products have changed their formulations with minimal fanfare. There’s no indication of “new” on the label.

To compound the confusion, labels on the revised formulation closely resemble the old ones. Unless the user is more observant than average, it’s very likely something may go awry. The application method may have changed; the precautions may have been modified; and/or the end result may be different than expected.

The explanations below were published in “When Familiar Pesticides Change.” (“Pests in the Urban Landscape;” August 29, 2018.

When Sevin is no longer carbaryl

Sevin is a familiar insecticide brand name for home gardeners used to control insects in lawns, on ornamental plants, and on vegetables. Sevin and the active ingredient carbaryl are practically synonymous. Recently, the active ingredient in some Sevin products was changed from carbaryl (a carbamate) to zeta-cypermethrin (a pyrethroid).” . . .  This pyrethroid is less toxic to mammals but both carbaryl and zeta-cypermethrin are highly toxic to bees and aquatic species. The new label on Sevin Insect Killer states that it controls more pests than the old product containing carbaryl, which may seem great, but the product may also kill some of the good bugs like lady beetles (ladybugs).

Product labels often look very similar, even when the ingredients change. On the left is the recently released product containing zeta-cypermethrin; the former version on the right contains carbaryl.

Another very important difference is the time the products can safely be applied on fruits and vegetables before harvest (called preharvest interval or PHI). Following the PHI reduces your pesticide exposure when you eat the food. For fruits such as apples and peaches, the PHI for the zeta-cypermethrin Sevin is 14 days, but for the Sevin with carbaryl it’s 3 days. For other fruits and vegetables, the PHI for the new Sevin label may be shorter than the carbaryl label. Again, check the label.

When Roundup is no longer glyphosate

Another familiar pesticide name is Roundup, a product known historically for containing the herbicide active ingredient glyphosate. Monsanto, the manufacturer of Roundup, now produces an extensive line of Roundup products containing multiple active ingredients, rather than just glyphosate alone. Many of these products contain triclopyr or diquat in addition to glyphosate. Some don’t contain any glyphosate at all

“Roundup Landscape Weed Killer” is a new product which contains pendimethalin instead of  glyphosate. It’s both a non-selective herbicide and a pre-emergent.

When Corry’s Slug and Snail Killer is no longer metaldehyde

In 2012, the active ingredient of the well-known Corry’s Slug and Snail Killer was changed from metaldehyde to sodium ferric EDTA, but the general look of the product box didn’t change. This relatively new active ingredient is less toxic and less attractive to dogs and still effective against snails and slugs. However, the amount users apply and how quickly it works both differ from the previous active ingredient. If you are familiar with the old product you may have noticed a change, but unless you read the label, you may not know why.

A Bonus Snippet on a different topic

MGs who volunteered this summer probably received multiple inquiries about the seemingly overabundant wasps this summer.  Well, the general public is seriously confused concerning the differences among bees, yellowjackets, and paper wasps. When they see a somewhat elongated yellow and black insect, they assume “wasp;” that is, yellowjacket. (Don’t bother asking how I know.)

But yellowjackets have a near twin: European paper wasps, Polistes dominulus, invasive insects officially identified in Oregon years ago. Most paper wasps are mild-mannered whereas P. dominulus is nasty. To easily differentiate them from yellowjackets, check the antennae. Text and images are at “Invasive paper wasp responsible for increasing yellow jacket complaints.” ( )

PDF Version:
When Pesticides Change

Natter’s Notes

Coping with the Heat; Leafrollers on Succulents;
Japanese Beetle Update

Jean R. Natter, OSU Master Gardener

Japanese Beetle Update from ODA

Japanese Beetle

The Oregon Department of Agriculture has completed its main treatment operations for Japanese beetle for 2018. From April 2 to June 1, ODA and General Tree Service, a contracted pesticide applicator, treated approximately 5,800 residences, 5 schools and 4 parks, 2 shopping centers and 1 golf course for Japanese beetle in Washington County. This number was increased from the 2,100 homes treated in 2017. In addition, an area of Portland International Airport and about 30 homes in Oakland, OR, were also treated due to beetle detections in 2017.

Community support for the project is very positive. We received consent to treat from over 5,100 residents! This success of this project depends on this kind of support from the community. We also served around 400 administrative warrants to residences from which we had not received a response. Residents have been sending in reports of beetle sightings. Thankfully, almost all of the reports of “serious infestations” of Japanese beetle have been determined to be box elder bug or other pests. [Editor’s emphasis.]

The project has entered trapping and detection phase for 2018. Seasonal survey staff are in the process of deploying 5,900 traps to detect Japanese beetle throughout the greater Portland metro area and the northern Willamette Valley. . .

No Japanese Beetle logo
Image courtesy of the Oregon Department of Agriculture

It’s still too early to make any conclusions about success of the project from this season’s data, but early numbers are very encouraging. Our first detection of JB in Washington County this year was on June 17. . .  As of July 21, 2018, we have captured 386 beetles total in the 9 traps. At the same time in 2017, we had captured 2961 . . .  these numbers are early and there are many more traps to check, but a reduction is good news, especially in the most active beetle areas. Final trap catch numbers will tell the whole story, and will be available late Summer/early Fall . . .

Our containment operations are also in full swing. Curbside yard debris bin contents are being redirected to Hillsboro landfill, as they were in 2017. Debris moved offsite by landscapers working in the quarantine area are being reminded and encouraged to take debris to our drop-off site at Northwest Landscape services. Residents in the area and landscapers that we have contact information for have been sent two reminders this season. Flyers in English and Spanish are also available on our project website,

The Oregon Department of Agriculture would like to express its sincere appreciation to the residents in the Japanese Beetle treatment area for their cooperation, as well as all of the partner agencies that have offered support, advice, time and energy to the project. This eradication is one of the largest ever undertaken by the department and would not be possible without the help of the community and partner agencies. This is a multi-year project, and is proposed to continue until 2021. . .  In the meantime, . . .  check for updates on

Coping w/ the continuing heat:

– Water early morning (by 6 am) or late day.

– Don’t assume a droopy plant is dry; check the soil with a trowel or finger. Excess soil water can kill.

– Realize that plants (and soil or potting mix) are drying more rapidly than usual. (Blossom end rot is rampant during heat waves because of erratic water supply.)

– Move containers to the shade and/or rig temporary shade 18 inches above sensitive plants.

– Mulch: Add two inches of bark dust or, for shrubs and trees, 4 inches of bark chips.

– Don’t fertilize.

– Mow the lawn high, at 3 inches or so.

Oblique banded leafroller on succulents

Leafrollers and leaftiers are common minor pests of various trees but, this year, the oblique banded leafroller has targeted several succulents, making an unsightly mess of tip growth, precisely where the flower buds should be. The victims: two rather stately sedum cultivars, ‘Matrona’ and ‘Autumn Joy.’ The remedy is simple: Pull the webbing apart and squish the little beasts. See “leafroller and leaftier” in the PNW Insect Management Handbook:

PDF version

Coping with the Heat; Leafrollers on Succulents; Japanese Beetle Update PDF

Natter’s Notes

Blister Mites: Grapes; Pears; Walnuts

Jean R. Natter, OSU Master Gardener

Erineum mite damage on home garden grape leaves: “Blisters” on the top; corresponding concave areas on reverse filled white fuzzy material (enlarged leaf hairs). (J.R. Natter; 2016-04)

Blister mites are running wild this season. It seems that the perfect conditions combined for population explosions of these tiny, elongated mites which noticeably disfigure the leaves of grapes, pears, walnuts, and more. Among pears, even newly planted trees are victims. The symptoms are similar on all three genera but the specific causal agents – also referred to as eriophyid mites or simply eriophyids – vary.

Blister or eriophyid mites reside on the undersides of the leaves, injecting fluids into the leaf tissue as they feed. Those fluids cause the blistering on the top surface with the associated white “fuzz” (enlarged plant hairs) in the concave areas on the reverse. (So, no, it’s not fungal growth.)

Blister mites are far different than the more common spider mites. Adults are microscopic, light in color, cylindrical, tapered at the posterior end, with two pairs of short legs just behind the head. Nymphs are the same but are smaller.

Microscopic image of an erineum mite, Aceria species, elongated, 2 pair legs, size about approximately 1/100-inch. (

Grape Erineum Mites (Colomerus vitis) are microscopic, wormlike, with 2 short pairs of legs at the head end, and white-yellow in color. They overwinter between the outer bud scales and bud tissue and feed on leaves during spring and summer. Feeding from the undersides of the leaves produces a blistered appearance on the top of the leaves. At the same time, the corresponding depressions on the underside are filled with enlarged light-colored leaf hairs which shelter the mites from natural enemies and pesticides. In spite of how extensive and nasty-looking the infestation is, blister mites seldom affect grape health or production.

As the season progresses, the enlarged leaf hairs progress from white to yellow and, finally, brown. Then, from mid-August until leaf drop, the mites return to their overwintering sites beneath the bud scales.

Home management for grape erineum mites: Sprays aren’t needed. Dormant-season oils and insecticides used for other pests and sulfur applications for powdery mildew usually control this pest.”

Pear Leaf Blister Mites (Eriophyes pyri) feeding causes reddish to yellowish green blisters on the top surface of the leaves, often in 2 lengthwise rows, one at each side of the main vein. With time, the blisters turn brown or black. Leaves may drop prematurely. Loss of excess foliage weakens trees, reduces shoot growth, and interferes with fruit maturation and fruit bud formation. Feeding on fruit causes irregular, russeted spots which feel rough and somewhat scaly. PNW Insect says “Eriophyid mites move from tree to tree, perhaps by wind or carried on birds or insects.”

Home Management for Pear Leaf Blister Mites: Lime sulfur applications in the fall can significantly reduce populations of these mites the following year. (The trick, though is to obtain it in small home-use packaging.) Applications before bud swell can also be effective. Or apply superior oil as buds begin to swell.

Walnut Blister Mites (Aceria erineus)

Just as do the previous two mites, walnut blister mites overwinter beneath bud scales. When springtime temperatures rise, the mites feed among the leaf hairs on the undersides of the leaves. Several generations occur during the summer, which attack new foliage as soon as it unfurls.

Home Management of Walnut Blister Mites: Naturally-occurring predator mites almost always keep mites under control if broad-spectrum insecticide applications are avoided. Heavy rain and cold weather also suppress mite numbers.

Broadleaf weeds like mallow, bindweed, white clover, and knotweed enhance mite numbers. Avoid excessive nitrogen applications, as this encourages mites.

Horticultural oil is the only spray suggested for home-use.


Eriophyid Mites:

Grape Erineum Mites:

Pear Leaf Blister Mites:

Walnut Blister Mites:

(Click the link below for PDF containing the above text and all the images.)

Blister Mites – PDF

Natter’s Notes

Pear Trees: Rust, times 2

Jean R. Natter, OSU Master Gardener

Pear trees are having a rough time of it this spring. It seems that this year supplied  the perfect conditions for rust on pears. So, let’s compare and contrast  the two important rust diseases of pears in Oregon. Recall that cedar-apple rust is not an issue in our region.

Seven different Gymnosporangium species cause rusts on members of the rose family in Oregon. For this discussion, let’s differentiate between Pacific Coast Pear Rust (G. libocedri) and Trellis Pear Rust (G. sabinae).

Most rust fungi have two different hosts: the primary host  — in this case, pear– on which growth and yield may be severely affected and a secondary host which typically displays subtle effects. With both diseases, pear trees exhibit brilliant orange spores on affected tissues, spores which readily rub off.

Numerous powdery, bright orange spores are present on leaves, twigs, blossoms, and fruites in Pacific Coast Pear Rust.
Numerous powdery, bright orange spores are present on leaves, twigs, blossoms, and fruits in Pacific Coast Pear Rust, as shown here and in Trellis Pear Rust. (Client image; Lincoln County; 2012-05)

Pacific Coast Pear Rust is a well-established disease in the northwest and, this spring, is on a spree infecting leaves, twigs, blossoms, and newly set fruit. All ages of trees are affected, from venerable specimens to newly planted saplings. Incense cedar is the alternate host.

Trellis rust, aka European Pear Rust, was found in western Oregon in 2016. It’s considered well -established in western Washington, coastal British Columbia and Contra Costa County, CA. Known infections in Oregon are in Benton, Marion, and Clackamas Counties. Junipers are the alternate hosts.

Trellis Pear Rust, also called European Pear Rust, on back surface of leaf.
Trellis Pear Rust, also called European Pear Rust, on back surface of leaf. (Client image; Multnomah County; 2017-09)

Differentiating between these two rust diseases of pear relies on careful examination of symptoms on submitted sample(s) and images. Both rusts sport bright orange, powdery spores on pears. A diagnostic symptom for the trellis variety is an “acorn-like” eruption on the backs of leaves later in the season.

Be certain to ask about potential alternate hosts nearby.  Both alternate hosts of these pear rusts ooze orange gel during wet spring weather. Off-season, affected junipers have subtle, elongated galls while incense cedars may develop  a more obvious symptom, witches’ broom(s). (

Management choices are limited for home gardeners who fear for their fruit crop.

– Sanitation –The common advice to collect and discard affected parts is unlikely to limit rust unless alternate hosts are removed.

– Resistant varieties – Growing resistant varieties is commonly suggested for disease management for backyard trees. In pear rust, both Asian and European kinds are affected. ‘Bartlett’ is usually less affected while ‘Winter Nellis’ is severely affected. Resistant varieties aren’t listed for trellis rust.

The PNW Disease Handbook states “Eliminating either host [primary or secondary] is the only practical cultural control.” For Pacific Coast Rust the PNW says “Remove alternate hosts around the orchard.” (It also states that, spores from the gel on incense cedar can be blown 6 for 10 miles.) The advice is more specific for trellis rust: “Remove all junipers within 1000 feet.”

No home-use chemicals are listed for either rust. So, the gardener’s next predicament is to locate a company which sprays fruit trees. Clients will need to research local companies that spray landscape trees. (I found that company websites usually offer a link to “contact us” while some list a phone number. You’ve heard it before: Let your fingers do the walking.)


Pear Trellis Rust

–  Pear, primary host –

– Juniper, secondary (alternate) host-

Pacific Coast Pear Rust

–  Pear, primary host –

– Incense cedar, secondary (alternate) host-

(Click the link below for PDF containing the above text and all the images.

Pear Trees: Rust, times 2 – PDF

Natter’s Notes 

Update: Japanese Beetle

Jean R. Natter, OSU Master Gardener

No Japanese Beetle logo
Image courtesy of the Oregon Department of Agriculture

The Oregon Department of Agriculture (ODA) has an extensive website with information about their continuing efforts to eradicate the invasive Japanese beetles (JBs) from Washington County, Oregon, which is expected to require 5 consecutive years of treatment. (Treatments began in 2017..) For a history and overview of the project, including all public updates beginning with March 2017, see ODA’s website at

ODA advises that adult Japanese beetles (JBs) found within the designated treatment area should be disposed of in soapy water. If JB adults are observed outside the treatment area, capture it/them and, then, promptly notify ODA by email at or phone 1-800-525-0137.

The following is the full text of the most recent Oregon Department of Agriculture update (April 16, 2018) for the ongoing eradication effort of the Japanese beetle in Washington County:

– – – –

The Oregon Department of Agriculture has begun treatment operations of residences in Washington County as part of the second year of Japanese beetle eradication. Oregon Department of Agriculture has contracted General Tree Service to perform the applications of the larvicide. General Tree Service (GTS) worked with ODA during the first year of the project, and has worked with ODA on past eradication projects for Japanese beetle in Oregon in years prior.

The treatment area in Washington County for 2018 is approximately 2000 acres containing an estimated 6500 residences. As of Friday, April 13, ODA and GTS had treated 2,049 properties for Japanese beetle. Four application crews consisting of one ODA team lead and two General Tree Service applicators and staff meet each morning at 7:30am to prepare the day’s plans. Treatment begins at around 8:15 am when the ODA team member visits each home to inform the resident of the treatment, inspects the property for hazards or areas to avoid application, and flags the property to let the crew know it’s ok to treat. Residents are notified about treatment schedules the week before.

– JB life cycle – Adult Japanese beetles are active only during a brief window during the summer months but are capable to doing considerable damage to numerous ornamentals. Credit: Lifecycle illustration by Oregon Department of Agriculture, Thomas Shahan

There have been some delays due to weather, but mostly treatment has been able to be completed as scheduled. This is due in large part to the hard work being done by the seemingly tireless application crews and crew leads who are working long days, rain or shine, to make sure treatment is correctly and done on time. Operations are expected to continue until mid-May, with some applications planned in Douglas County and at the Portland International Airport.

Support from resident in the area has been very positive. Before treatment, we’d received over 5,000 responses from residents allowing ODA and their staff to treat the properties, including 30 Home Owners Associations allowing treatment in common areas. Tualatin Hills Parks and Recreation Department and the Beaverton School District are also supporting the project and allowing treatment to parks and school fields. Applicator crews have said that residents in the area are expressing their support for the project, with many “Thank yous” and “Get those beetles!”

Containment will begin ramping up soon, with the yard debris quarantine still in effect and expanding in 2018. Residences will receive electronic notices from Oregon Department of Agriculture this week, along with other communications planned throughout the summer.

– Chris Hedstrom, Japanese Beetle Project Coordinator

(Click the link below for PDF containing the above text and all the images.)

Japanese Beetle Update PDF

Natter’s Notes:
Carpenter Ants

Jean R. Natter, OSU Master Gardener

Fig 1: Relative size of carpenter ants: Top row: Winged queen (L) and winged male (R); 3 sizes of workers in bottom row: minor (L); media (center); and major (R). (

Carpenter ants, sometimes referred to as “termites of the northwest,” can be important structural pests which typically nest in moisture-damaged wood. In our region, swarms of flying reproductives (males and females) often leave the nest during January. After mating, the surviving queens will shed their wings and search for a new nest site.

Once a thriving colony is established, it has 10,000 to 50,000 or more individuals. The main nest is in dead wood, perhaps a tree, stump, or landscape timbers.

But that’s only part of the story.

The pupae and some workers are in a secondary nest, one that’s in a relatively warm, dry structure such as a house, garage, or shed. When a colony is about 6 to 10 years old, it produces its first winged swarmers (reproductive males and females). The females, at 16- to 18-mm (about 5/8-inch), are larger than the males, the latter a scant 1/2-inch long.

It doesn’t matter which Camponotus species is in an infestation. In western Oregon, C. modoc (black with red legs) is more common than C. vicinus (black with red thorax and legs). A mature colony has 3 sizes of workers: minors (the smallest); media; and majors. They may invade households, just as nuisance ants will, but are unaffected by over-the-counter ant bait.

Fig 2: Characteristics of carpenter ant workers are elbowed antennae; evenly rounded thoracic profile; and a large node on the narrow connection between thorax and abdomen. (

All ants have elbowed antennae, and a petiole (a slender connection between thorax and abdomen) with a noticeable node (a bump).  Carpenter ant workers are recognized by their particularly large node and an evenly convex thoracic profile. The additional musculature for the swarmers’ wings creates a beefier profile changing the thoracic outline to somewhat flattened and table-like. After females drop their wings, close examination of the lateral thorax with a hand lens will reveal small indentations – the places where the wings were attached.

Key points

  • Secondary nests in structures begin in moisture-damaged wood.
  • Buildings near a wooded area are more liable to attack than others.
  • Carpenter ants don’t eat wood; instead, they excavate wood for housing.
  • Carpenter ants feed on honeydew and captured insects.
  • If winged ants emerge indoors from underneath the baseboard, the nest is probably in the wall; if via a ceiling light fixture, in the space above, in either the attic or ceiling void.

More often than not, clients don’t know if they are infested or where the main nest is.  These activities can provide answers:

  • Look for piles of fresh sawdust in the attic and crawl space.
  • To determine where the ants are entering the structure, look for 2-way trails outdoors. The best time is from 10 PM to 2 AM during April through October. Inspect along the foundation and other architectural lines, in the crawl space, and where utilities (pipes and wiring) enter the structure.
  • If a trail is found, follow it to the main nest which, to limit structural re-infestations, must be treated by a pest control company.
Fig 3: Queen carpenter ants shed their wings after mating. Additional muscles for the wings change the thoracic profile to somewhat table-like. (

Thwart the likelihood of a carpenter ant infestation with several ongoing practices:

  • Create an airy clear zone around structures by trimming, or removing, any plant material within 12 to 18 inches.
  • Maintain mulch at least 8 inches below the siding.
  • Ensure roofing is intact.
  • Inspect the perimeter of the structure periodically, to check for a 2-way trail which warns of an infestation.

Management practices for an infestation

  • Hire a pest control company to treat the structure and, whenever possible, the main nest.
  • Correct the moisture problem and replace damaged wood
  • Over-the-counter ant baits available in the northwest are ineffective against carpenter ants.


– PNW Insect Management Handbook, the section titled Structural and Health Pests.

– “Identification and Habits of Key Ant Pests of Washington” (EB0671) has identification details for common ants.

“Carpenter Ants: Their Biology and Control” (EB0818; WSU)

– “The Technician’s Handbook” (Richard Kramer; PCT Handbooks) is a handy source of brief summaries about key pests. Each entry includes the pest’s description, a clear line drawing, life cycles, foods, habitats, and cultural management.  Still more details about ants are in “Structure-infesting Ants” (Stoy Hedges; PCT Handbooks). These professional handbooks offer insights as to the services pest control companies may offer. For one thing, pest control companies have effective ant baits not otherwise available to the public.

(Click the link below for PDF containing the above text and all the images.)

Carpenter Ants PDF

Natter’s Notes


Jean R. Natter, OSU Master Gardener

Odorous house ant, Tapinoma sessile; lateral view.
Fig 1. Odorous house ant, Tapinoma sessile; lateral view. The small petiolar node is hidden by the abdomen. (From Accessed 11 January 2018;

Ants! They’re likely major players in perhaps one of the oldest good-news-bad-news stories ever.

The good news is that ants are valued for their beneficial activities. They add large quantities of spent plant and animal remains into the soil surrounding their colonies as they cultivate and aerate the soil. They also create channels for water and roots. They’re predators, too, and are members of nature’s clean-up crew, carting away debris that includes stray crumbs indoors and dead insects outdoors.

The bad news is that, outdoors, ants sometimes get carried away. If they aerate the soil in and around a rootball excessively, water passes through the ground too rapidly to soak in, the plant wilts, and may die. Then, too, people take a dismal view of their uninvited excursions indoors when they trail across the floor, headed for the pet’s dish or wayward crumbs.

Overall, it’s safe to say that most people detest the little buggers. People don’t want to control them. They want to eradicate them. Forever!.

Well, the cold, hard truth is this: That’s not possible; ants are here to stay.

Everyone, clients and Master Gardeners alike, must discard their dreams to eradicate ants. The more accurate strategy, although far less comforting, is to hope to manage ants.

Odorous house ant, Tapinoma sessile; dorsal view.
Fig 2. Odorous house ant, Tapinoma sessile; dorsal view. Notice the small petiolar node hidden by the abdomen. (From Accessed 11 January 2018)

Odorous house ants, Tapinoma sessile, are probably the most common house-invading ants across the country. They’re small, dark brown or black ants, 1/16- to 1/8-inch long, with the usual 3 body parts of an insect – head, thorax, and abdomen. The characters which define them as ants are a petiole (a narrow connection between the thorax and abdomen) and a pair of elbowed antennae. The character which differentiates them from other ants is the single node on the petiole; it’s small and hidden by the abdomen. When crushed, these ants emit a rather penetrating odor, likened to rotted coconut.

Colonies are relatively small, to about 10,000 individuals, each with multiple queens. Nests are usually outdoors just below the soil surface, underneath pavers, wood piles, or other debris. But nests may also be indoors, in a wall void or near warmth-emitting sources.

Odorous house ant populations enlarge by one of two methods: mating of reproductives or via budding. Budding may be triggered when a hundred or so workers transport several of the colony’s queens to a new site. With time, a series of closely related, cooperative colonies—a supercolony – forms.

Sweets are a favorite food but they will eat most any people or pet food.

Managing ants requires a multi-pronged approach.

  1. Sanitation (clean up regularly), and store perishable foodstuffs in tight, rigid containers.
  2. Caulk and seal entries such as cracks in the foundation or gaps where utilities enter structures.
  3. Limit honeydew-producing insects: ants, mealybugs, whiteflies, and scale, both soft and cottony scales.
  4. Limit access indoors by trimming foliage away from structures.
  5. Use commercially-formulated ant baits and repeat as needed.
Aluminum cast of ant nest (species not identified) reveals the extent to which some ants will go.
Fig 3. Aluminum cast of ant nest (species not identified) reveals the extent to which some ants will go. (Cast by Walter R. Tschinkel, entomologist and former professor at Florida State University.)

Ant baits are superior to sprays but require more time to be effective, occasionally several weeks. The reason? They are shared with other ants within the colony, including the queens. If a bait is ineffective after a week or more, try a different kind. It can be useful to pre-bait by first setting out a small dab of jam or other food.

Active ingredients in commercial ant baits

  • Avermectin – Derived from soil bacteria; affects the nervous system.
  • Boric acid – An inorganic compound used in ant management for years. Mode of action unknown.
  • Fipronil – Causes hyperexcitation of the central nervous system causing convulsions and death. Very active against ants.
  • Hydramethylnon – Interferes with energy production.
  • Imidacloprid – Useful in baits for ants that prefer sweets.
  • Insect growth regulators (IGRs) – The queen’s reproductive organs degenerate and immatures die before they become adults.
  • Indoxacarb – Activated by enzymes inside the insect.
  • Spinosad – Produced by soil actinomycetes; the insect dies of exhaustion because of continuous activation of motor neurons.
  • Sulfuramid – Potentiated by enzymes inside the insect body; toxic metabolites inhibit energy production.


(Click the link below for PDF containing the above text and all the images.)

Ants PDF