Garden News April 2023

Japanese Beetle Eradication update

The largest infestation of Japanese beetles ever found in the state was detected in 2016 in the area of Cedar Mill, Bonny Slope, Oak Hills, and Bethany of Washington County in Oregon. We have a unique and brief window of opportunity to ensure the population does not become established in Oregon. Failure to eradicate the current population will result in a widespread destructive population that will be impossible to stop from ultimately spreading throughout the western United States. Learn more here.

Property treatments were completed in late July 2022, and the last traps were collected in October. We had snow in May, an unseasonably long and rainy spring, and consecutive days of heat in July. Weather impacts our ability to carry out our Japanese beetle treatments, causing delays and rescheduling. We thank you for your patience and cooperation. Of those who responded to our consent letters over 96% consented to treatment last year!

For the 2022 season we successfully trapped 3254 Japanese beetles, which is more than a 10% reduction in overall beetles caught in 2021. Because of the 2021 granular treatments and 2022 foliar treatments, there was a 12% reduction in number of beetles trapped in 2022 within the 2021 treatment boundary. 2022 marked the first year that we reduced the size of the treatment area. This was possible because of your continued support, the hard work of our seasonal crews, and the assistance from our cooperators, General Tree Service (GTS), Best Buy in Town, and the Hillsboro landfill, who provided yard waste collection to keep contaminated material from escaping our area. We have continued that trend into the 2023 season with about a 30% reduction in the planned treatment area for this year.

Visit the map to see if your property is in the treatment area

Oregon Department of Agriculture (ODA) has been sending out consent forms for the 2023 season since late January. Treatment begins the second week in April.  If you didn’t get the treatment notice, you may not be in the treatment area now. View this year’s treatment area on the GIS map here. Reminder: we ask for consent from each residence in the treatment area every year. ODA appreciates your willingness and support to help our program. Each season, we get closer to our goal of eradicating Japanese beetle and protecting Oregon from this harmful pest.

Another harmful pest on our doorstep

Notice the D-shaped hole that the beetles make in bark

The emerald ash borer (Agrilus planipennis) is considered the most destructive forest pest in North America. It is a very small, yet extremely harmful non-native insect that kills all species of ash trees. Emerald ash borer (EAB) has decimated millions of ash trees since it was discovered in Michigan in 2002. Biologists have been tracking its inevitable spread across the country, and it was finally discovered in the Forest Grove, Oregon area in 2022.

In the greater Portland area and throughout the Willamette Valley, we are especially concerned about the devastating effects this insect will have on Oregon ash (Fraxinus latifolia). This tree is critically important for forested wetlands, riparian areas, and in our urban forest canopy. Learn more about EAB and what you can do to help.

[NOTE: a friend says he found one in Bonny Slope, where we have Oregon ash trees along all our creeks. Keep your eyes out for this pest and please report any suspected emerald ash borer insects or signs of infestation to or call 1-866-INVADER]

Master Gardener programs

The Washington County Master Gardener™ Association (WCMGA) sponsors a wide variety of gardening–related demonstrations, lectures, seminars, and workshops in various Washington County Oregon locations. Most of our events are free and open to the public. For more details, please click here. Below is a sampling of programs to attend:

Plant Propagation

Saturday, April 29, 10 am-noon, WCMGA Learning Garden at Jenkins Estate, 8005 SW Grabhorn Rd, Beaverton, free

Learn how to make more of the plants you love using a leaf, a twig, or a piece of root. Master Gardeners Karen Anderson and Cindy Muir will show you the basic elements of plant propagation.

Perennials: How to Choose, Plant, and Maintain for Year-Round Flowers

Saturday, April 22, 10 am-noon, PCC Rock Creek Campus Building 4, Room 103, free

Learn how plants give the garden beauty, food for wildlife, and create an ever-changing tapestry of color with presenter Lisa Graff. They are a good investment since they come back year after year. This class will discuss different types of perennials, from easy care to more challenging, and how to best care for them in terms of planting, pruning, fertilizing, pest control, and general maintenance, plus tips to extend blooming time for year-round color.

Presenter Lisa Graff retired in 2016 after a 28 year career at Intel Corporation in electrical engineering and business. She has had a passion for gardening for decades with a focus on densely planted, continuously blooming perennial beds. After retirement, she became a Master Gardener and blended her love of science with gardening and began propagating plants. She opened Lux Perennials Nursery in 2020 and has opened her one-acre English garden for tours and to customers at her nursery.

Gardenfest Plant Sale

Saturday May 6, 9 am-1 pm, PCC Rock Creek Campus Hoop House area near Building 4,17705 NW Springville Road, free parking

Come along for a fun-filled day shopping from a selection of thousands of plants expertly selected for the Pacific Northwest. You can also get ideas from our Education garden and ask gardening questions at our “Let’s Talk Plants” booth. The sale will offer perennials, shrubs, vegetables, houseplants and more for flower-filled gardens and bountiful harvests.

Our Master Gardeners are delighted to welcome you, inspire you, and help you succeed in your garden by providing practical knowledge on plants, garden care and diagnosing problems. There will be kids’ activities and Gifts for Gardeners, too. OK to bring wagons—please, no pets.

SWCD hosts spring workshops and events

Various dates, times, and locations, some are free. For details please click here.

Tualatin Soil & Water Conservation District is hosting an array of workshops and events this spring. Join us to learn about soil, how to identify priority weeds, and to celebrate agriculture in Washington County.

Weed Watchers

Wednesday, April 12, 6 pm, Tualatin SWCD, 7175 NE Evergreen Pkwy #400, Hillsboro

Join a Weed Watcher Workshop and learn how you can help prevent the spread of invasive species in our community. This workshop highlights Early Detection and Rapid Response (EDRR) weeds in the Tualatin River watershed.

Soil School

Saturday, April 15, 8 am-3 pm, PCC Rock Creek|, 17705 NW Springville Rd, $35 per person

Soil School offers multiple sessions on a wide variety of topics related to soil and soil health. This year’s event is back in person at PCC Rock Creek for classroom and outdoor hands-on sessions! Registration is open until noon, Thursday April 13, and space is limited.