September’s Weed of the Month: Shiny Geranium

By Jade Keehn, ODFW Wildlife Habitat Biologist

Shiny geranium (Geranium lucidum) is an annual weed native to Eurasia. This species is a recent invader in Oregon with a strong foothold in the Willamette Valley. Shiny geranium was first documented in the Rogue Basin in the mid 2010’s and populations have since expanded along the Rogue River corridor (from Gold Beach to Galice) and through Forest Creek north of Highway 238. Additional undocumented infestations may be present in Jackson and Josephine counties—habitats likely to harbor this species include disturbed sites (lawns, gardens, pastures, and roadways), riparian corridors, oak woodlands, and forest edges and openings.

As an early-season bloomer, shiny geranium can rapidly expand into new areas where it quickly becomes established by producing multiple generations each growing season. If left uncontrolled, shiny geranium will form dense monocultures characterized by few native understory species. Invaded sites provide limited cover or forage value to wildlife.

Relative to similar species, shiny geranium can by identified by its 5- to 7-lobed waxy or shiny leaves (sometimes sparsely hairy), flowers with 5 pink petals, keeled sepals with transverse ridges, and stems that become more red in color as leaves senesce.

Shiny geranium begins to sprout in the fall. By springtime, plants will start to form dense patches. Flowers are visible in May and seeds mature by late June to July. Each plant can produce hundreds of seeds that are easily transported by livestock, pets, wildlife, people, or in other plant materials.

Shiny geranium can be difficult to remove by hand. Seeds remain viable in the soil for two or more years, and plants can resprout if not completed removed. Smothering infestations with mulch can reduce densities, and herbicides such as glyphosate can be applied in the fall. Some land managers have controlled shiny geranium populations through a combination of tilling, spraying, and re-seeding with native species.

Have you seen this species in the Rogue Basin? If so, please report your sighting to the Oregon Invasive Species Hotline, or visit the Oregon Department of Agriculture’s Weed Program website to contact your local Cooperative Weed Management Area partners.

August’s Weed of the Month: Yellow Starthistle

By Kristi Mergenthaler, Southern Oregon Land Trust

In pastures, roadsides, oak woodlands, meadows and over buried pipelines and under power lines, the spiky yellow flowers and frosty vegetation of nonnative invasive yellow starthistle (Centaurea solstitialis) is a familiar sight in the Rogue Basin. This noxious weed is native to the Mediterranean and was first introduced to the region around the time of the California Goldrush in the 1850s through contaminated forage brought from Chile. Why should you care?

            Honey bees like it, right? 

            Love horses? Yellow thistle is poisonous to horses and can be fatal.

Proud of our natural heritage of rare and uncommon native plants, some of which grow nowhere else in the world, in the Klamath-Siskiyou Ecoregion? Enjoy the beauty of a meadow full of spring flowers? Starthistle is a monoculture specialist and is especially effective at taking over oak woodlands and meadows. It extinguishes biodiversity.

Fond of pollinators? Honey bees and native pollinators require a diverse menu of pollen and nectar from many flowering species from spring through fall. A monoculture of starthistle only provides resources for a brief time. A field of summer-dried starthistle stalks has no value for bees or butterflies.

Want to sell your hay? Hay contaminated with starthistle harms horses and helps spread starthistle to new locations and decreases the value of your product.

Want to tiptoe or stroll through a meadow? Walking through a field of dry and pokey starthistle is unpleasant and can be barrier to the movement of wildlife. Dry starthistle stalks can also increase wildfire hazard.

What to do? ?

Just pull it! Starthistle is an annual plant so target pulling plants before they go to seed. Prioritize removing small infestations, along corridors like roads and trails, and around buildings.  There may be multiple generations at a site so monitor for new plants and pull. The seeds remain viable in the soil for around three years, so please pull plants every year until gone.

Going on a hike? Please pull for a good cause and stop for a few minutes and pull starthistle along roads and trails. The natural world gives you solace and fun, give back.

Stop the seeds! One starthistle plant can spread as many as 30,000 seeds per square meter, with up to 95 percent of the seed being viable. Remove vegetative and early flowering plants before the seeds develop.

When working with contractors, require the use of clean equipment and weed-free gravel fill. Roadwork and construction are some of the main culprits in spreading starthistle and other noxious weeds.

Other control options include careful mowing, prescribed burns, irrigation, and managed cattle, goat, or sheep grazing. For more info: https://www.oregon.gov/oda/shared/Documents/Publications/Weeds/YellowStarthistleProfile.pdf.

July’s Weed of the Month: Saltcedar

Saltcedar, also known as tamarisk, is an invasive shrub or small tree that is found across the American West. Populations are prevalent along waterways east of the Cascades, but last week members of the Applegate Partnership & Watershed Council identified it along the mainstem Applegate River near Provolt.

The plant was intentionally introduced to the West in the 1800s as an ornamental, windbreak, shade, and erosion control species. They can grow to be anywhere from 1-18 m and foliage ranges from dark green to a light greygreen depending on the species.

Ecosystem impacts from salt cedar can be significant. They provide poor wildlife habitat, restrict access to rivers, and increase soil salinity, making it capable of easily displacing native species like cottonwoods and willows. Their leaves are flammable which can serve as potential fuel, significantly increasing an area’s wildfire risk.

Conventional control methods, including mechanical cutting and herbicide applications are effective but limited by cost. Communities in the Colorado River Basin have successfully used the Tamarisk Beetle as a biocontrol.

Please notify info@roguepartners.org if you see this species growing in the Rogue Basin.