WSU Extension
Ask a Master Gardener
Free access to unbiased research-based horticulture advice
We’re trained to help you!
For more than a half century, home gardeners have been bringing us their questions and issues. We have University trained volunteers who can help you tackle those intractable problems! Our diagnostic team specializes in pinpointing issues with plants and pests, offering free research-based advice on effective management strategies for both the pests and the overall health of gardens and landscapes.
You can also do a quick lookup in our collection of local weeds and pests that we have compiled for you.
More Information
Ask a Master Gardener
Physical Samples
Bring in a plant or bug to the Stevens County Extension office!
- Samples must be in a sealed, transparent glass or plastic container.
Master Gardener Office Hours:
(Mid-March through late September)
- Mondays, 9-11 a.m.
- Thursdays, 1-3 p.m.
Ask a Master Gardener Email/Online
For your convenience, you can submit questions, including photos, by either:
- emailing us at: AskaMasterGardener@stevensmg.org
- filling out the Question Submission form
Photos should be in focus, and if possible, taken close up and farther back, and/or from different angles if needed. The next time Master Gardeners are in the office, they will research your question/issue and send a detailed email response.
Help us to Help You: please complete the appropriate form below and include it with your sample/question.
- Lawn or Turf Problem Diagnosis Form (pdf) – Use this form for any lawn/grass/turf issues.
- Ornamental Plant Problem Diagnosis Form (pdf) – Use this form for any Ornamental plants or garden issues.
- Insect (Pg 1) or Plant/Weed (Pg 2) Identification Form (pdf) – Use this form for any insect or plant you want identified.
NOTE: We do NOT do soil-testing at this office. Soil-testing laboratories in Eastern Washington can be found in this downloadable PDF (instructions on collecting a good soil sample included): Soil Testing Packet (pdf)
Other Research-Based Resources
Hortsense
Hortsense contains home gardener fact sheets for managing plant problems.
Other gardening resources
Find publications and links to a vast library of gardening resources.
Evergreen Thumb Podcast
Gardening Tips and Insights with WSU Extension Master Gardeners
Local Gardening Info
Weeds to Watch Out For
Hoary Alyssum
Hoary Alyssum, Berteroa incana, is a noxious weed in the Mustard family. It is most abundant in disturbed sites but also can be found in meadows and pastures. White, four-petaled flowers at the top of the plant It spreads rapidly through seed only and it has a high number of seeds per plant. Can be toxic to horses if it is 30% or more of their diet and can be a problematic invader of alfalfa crops.
Tansy Ragwort
Tansy Ragwort, Jacobaea vulgaris, is toxic and a threat to livestock and agriculture. All plant parts are toxic, with the highest concentration of alkaloids in flowers then leaves, roots and stems. Toxic properties are a possible threat to humans through food chain contaminants. It is a biennial and during the second year, one or more flowering stems form. Disturbance, such as mowing, may cause the plant to behave as a perennial, appearing year after year.
Field Bindweed
Field Bindweed, Convolvulus arvensis, is a perennial plant with creeping and twining stems that grows along the ground and up through other plants and structures. It has an extensive system of rhizomes that can grow deep into the soil. Found in ravines, greenbelts, forested parks and farmlands, driveways, flower gardens, and ornamental borders.
Milk Thistle
Milk thistle, Silybum marianum, is a sparsely branched thistle growing up to 6 feet tall with distinctively patterned green and white leaves. Flowerheads are large and rounded, occurring at stem tips. Flowers are purple. Milk thistle is found in dense stands along roadsides, waste areas, pastures, ditches and disturbed areas.
Japanese Knotweed
Japanese Knotweed, Polygonum cuspidatum, is a noxious weed in the Buckwheat family. This previously-planted-as-an-ornamental can be found choking out other plants in riparian sites or roadside ditches, waste areas, and pastures. Woody stems can grow 4-9 feet tall and spreads rapidly by rhizomes, seeds, and stem pieces.
Purple Loosestrife
Purple Loosestrife, Lythrum salicaria, is commonly found growing in waste areas, roadsides, and sites with wet soil conditions. The plant will grow from 2 to 6 feet tall and spreads rapidly from underground shoots. This weed will make thousands of tiny seeds that spread easily through wind, water and animals.
Common Mallow (Cheeseweed, Buttonweed)
Common mallow is a weed of waste places, gardens, and cultivated areas. Leaves are alternate on the stems and have long, slender petioles. Each blossom has five white or pinkish petals with notched tips.
Common Tansy (Tanacetum vulgare)
Common Tansy, Tanacetum vulgare, is an aromatic perennial with rhizomes, reaching 1 to 5 feet tall, with fern like foliage and yellow button-like flowers. It is reported to be poisonous to livestock, though it is seldom grazed due to its strong odor. It is generally found along roadsides, waste areas, streambanks and in pastures.
Rush Skeletonweed (Chondrilla juncea)
Rush skeletonweed, Chondrilla juncea, is a threat to irrigated lands, wheat areas and rangelands. Rangeland infestations displace native and beneficial forage species grazed by livestock and wildlife. Plants begin as a basal rosette of leaves and then grow 1 to 6 branching flowering stems. Plants will exude a latex sap from injured surfaces. Click link to see a map of distribution in WA state.
Dandelions
The common dandelion is a persistent taprooted plant reproducing by seeds and by short shoots from the crown. It also grows back from roots broken during hand removal.
Insects to Watch Out For
Aphids
Aphids are small (1/16″ to 1/8″), soft-bodied, sap-sucking insects. Depending on species, their color can vary from green to yellowish to rose-colored or black. Some species may appear powdery or woolly. Adults are winged, but usually most of the infestation consists of wingless individuals. Aphids are often found near the tips of shoots, preferring tender new growth where they may cluster in large groups. They also feed on the underside of leaves and on stems.
Cabbageworm
Caterpillars affect cabbage, broccoli, kale, collard greens and some other plants. Adult butterflies are commonly seen flying around plants during the day
– Adults are white butterflies with black spots on the forewings.
– Eggs are yellow and oblong and are on both upper and lower sides of leaves.
– Caterpillars can grow up to 1 inch in length and are velvety green with faint yellow stripes running lengthwise down the back and sides.
– They move sluggishly when prodded.
– Adults are white butterflies with black spots on the forewings.
– Eggs are yellow and oblong and are on both upper and lower sides of leaves.
– Caterpillars can grow up to 1 inch in length and are velvety green with faint yellow stripes running lengthwise down the back and sides.
– They move sluggishly when prodded.
Codling Moth (Cydia pomonella)
The gray wings of adult codling moths are marked with dark brown bands near the wingtips. Females lay eggs on leaves or fruit. The larvae burrow into fruits, usually through the blossom end, where they eat the core and seeds. The fruit appears dirty brown or rotted in the center when cut open. Codling moth is a serious problem in commercial apple and pear orchards. Because home-grown fruit trees can serve as alternate hosts for codling moth, homeowners in fruit-growing areas are encouraged to manage this pest to help control regional codling moth infestations.
Spider Mites (Tetranychidae)
Several species of spider mites may become significant pests on ornamental plants. Spider mites are very small, eight-legged arthropods that damage foliage with their piercing mouth parts. Strands or mats of silk webbing may be present on the underside of infested leaves or in the axil between leaf and stem. Cast skins, eggs, eggshells, and living mites are all commonly present in the webbing.
Mealybug (Pseudococcidae)
Mealybugs are common pests of houseplants. They are pink, soft-bodied insects covered with a white, waxy, cottony material. The white “fluff” helps protect them from excessive heat and moisture loss. Females are rounded, wingless, and about 1/16″ long. Yellowed or wilting foliage may indicate the presence of mealybugs on the roots.
Tomato Hornworm
Tomato Hornworm, Manduca quinquemaculata, is the caterpillar form of the Hornworm Moth.
They are very large caterpillars with a horn-like tail, and their favorite plant is tomato.
Hornworms chew leaves and can completely defoliate plants, as well as chew holes in the fruit.
Physical removal is usually the only necessary management
They are very large caterpillars with a horn-like tail, and their favorite plant is tomato.
Hornworms chew leaves and can completely defoliate plants, as well as chew holes in the fruit.
Physical removal is usually the only necessary management
Beneficial Insects
Lady Beetle (Coccinellidae)
There are about 90 species of lady beetles in the Pacific Northwest. The alligator-shaped larva is dark gray-blackish blue with two small, indistinct orange spots on the pronotum and four larger ones on the back. Lady beetles are industrious predators of not only aphids but also many other soft bodied arthropods like mites, thrips, insect eggs, scale insects and mealybugs.
Lacewing (Chrysopidae)
Adult lacewings are delicate-looking slender-bodied creatures (1/2 to1 inch) that fly weakly with lacy, netted wings. Larvae of the Lacewing eat mites, aphids, leafhoppers, whiteflies, thrips, mealybugs, caterpillars, insect eggs, and scale insects. Lacewing are also available to purchase in the Spring from many companies.
Predatory Beetle: Ground Beetle (Carabidae)
Carabids or ground beetles, as their name suggests, are ground-dwelling, living in soil and detritus, with some species preying on mites, aphids, leafhoppers, mealybugs, thrips, insect eggs and small larvae, scale insects, whiteflies. Avoid regular use of synthetic, broad-spectrum pesticides to attract & keep these beneficial insects in your garden ecosystem.
Predacious Hoverfly (Syrphidae)
Adult hoverflies look like and mimic wasps and bees but fly more quickly or hover more than wasps. Larvae prey on aphids and scale. Adults are important pollinators. They do not sting or bite but do harmlessly feast on human perspiration. Please do not kill Hoverfly!