weeds Archives - TreeTopics

By Amy Grotta, OSU Foresty & Natural Resources Extension – Columbia, Washington & Yamhill Counties

Holly foliage usually (but not always) has sharp, prickly lobes.

Rid your land of English holly

Fa-la-la-la-la, la-la-la-la

Tis the season to spot holly

Fa-la-la-la-la, la-la-la-la

When all the other leaves are gone

Fa-la-la, la-la-la, la-la-la

Holly’s deep green stands out strong

Fa-la-la-la-la, la-la-la-la

Ok, there’s a good reason I didn’t become a songwriter. The point I want to make, though, is that this is a great time of year to scout your woodland for a common and nefarious invasive plant: English holly. It stays green all year long, so now that herbaceous plants have died back and other shrubs have lost their leaves, it’s easier to spot. Continue reading →

Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent, Benton, Linn and Polk Counties.

Pretty much every landowner I know has a weed issue.

Some are fairly short term and narrow, such as controlling common weeds in a new tree planting. Others are much longer term and less defined, such as keeping invasive species at bay in the woodland, or perhaps encouraging native plants in a meadow or streamside restoration.

There are multiple approaches to weed management, including preventing new weed introductions, mechanical or physical control such as mulching or mowing and the use of herbicides. Most people use a mix of two or more of these approaches, with many including herbicides as one of the methods they use.

Here are some key resources to help you manage your weed issues.

Invasive Weed Identification and Management EC 1563

It is important to know the enemy, and this is a good place to start, beginning with the 3-page introduction. This publication goes on to describe the identifying characteristics, origin, habitat, ecology and management strategies for selected invasive weeds in the Pacific Northwest. This list is not inclusive of all invasive weeds, but focuses on the most dominant or potentially invasive species that plague us. Check PNW Weed Management Handbook for current herbicide recommendations.

The Nature Conservancy’s Weed Control Methods Handbook

A useful resource for many types of landowners, the Weed Control Methods Handbook: Tools & Techniques for Use in Natural Areas provides detailed information about weed control techniques including manual and mechanical methods, grazing, prescribed fire, biological control, and herbicides. Check PNW Weed Management Handbook for current herbicide recommendations.

Continue reading →

By Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent, Benton, Linn and Polk Counties

Last month I spent a morning at OSU attending the annual science meeting of the Vegetation Management Research Cooperative (VMRC). It was well worth the time.

The VMRC’s mission includes conducting applied reforestation research of young plantations from seedling establishment through crown closure and, to promote reforestation success. The VMRC’s research has an emphasis on practical, operational vegetation control, and their research is broadly relevant and readily applied to the needs of family forest landowners, so I do try to keep up on their work.
Continue reading →

By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties

Like just about any small woodland, the Matteson Demonstration Forest has its share of invasive weeds. Besides familiar and ubiquitous foes such as Scotch broom and thistles, one of particular concern is knapweed.

Meadow knapweed, photo by Eric Coombs, OR Dept of Ag, bugwood.org

With purple flowers emerging from roundish bases at the top of a tall stalk, knapweeds superficially resemble a sort of spineless thistle, and in fact they are relatives of thistles, botanically speaking. They are biennial (2-year life cycle) to perennial plants and reproduce by seed. Fairly inconspicuous in the winter and spring; at this time of year, their purple flowers betray their location on and along roadbeds and other disturbed areas. Continue reading →

By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties

Dead tips (upper branch) and stunted growth (lower branch). Photo taken in January 2015, eight months after herbicide was applied.

A local landowner contacted me this winter, concerned about his ten acres of young trees and whether they had been damaged by herbicides. In May 2014, a year after the trees were planted, grass was coming in thick, so he hired a contractor to do a release spray. We don’t know what the exact spray mixture was, but the landowner thought it may have been a formulation of glyphosate such as Accord. Glyphosate is known to damage Douglas-fir seedlings (and many other conifers) during the active growing season – the time from when buds begin to swell in spring until resting buds are formed and hardened off in fall.

Affected trees showed several symptoms characteristic of herbicide damage. The least affected trees simply had stunted growth. On many others, the leader and branch tips were droopy and dead. Some seedlings were completely dead. Continue reading →

By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties

Remember those Magic 8 balls where you would ask a question, shake the ball, and get an answer? I wish life were that simple.

Extension agents get a lot of questions. Some say we are notorious for always answering with “well, it depends.” As an Extension agent I’m as guilty as anyone of using “it depends”, and not because I want to dodge your question. Usually there is more than one answer; more information is needed; and ultimately, you are the one who will be able to answer your own question after more a more thorough evaluation. Here is a sampling of inquiries I’ve received by phone, email, or Ask an Expert over the past few weeks, to illustrate this. Continue reading →

By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties

As tree planting season winds down and the weather warms, we are already starting to see buds popping on spring’s earliest bloomers. Soon the spring explosion will be in full force. It won’t be long before the hillsides are brilliant yellow – and not with daffodils.

Photo: Eric Coombs, Oregon Dept. of Agriculture, bugwood.org

Colorful and abundant as it is, Scotch broom is one of the more serious forest weeds that we have to contend with. The Oregon Department of Agriculture has estimated the economic impact of Scotch broom on Oregon forestland at $47 million annually – that figure includes lost forest productivity and control costs. Continue reading →

By Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension – Benton, Linn & Polk Counties

Even a wall of blackberries can be tackled

In recent entries in this series on the basics of herbicide use in weed control, I have reviewed how some foliar herbicides work, and the relationship between the plant’s physiology and the herbicides’ behavior. Now I want to illustrate how that that information translates to what gets done in the woods, looking at controlling blackberries, a frequent target of foliar herbicides.

Blackberries are a problem because they are widely dispersed by birds and start readily from seed and once established, rapidly spread vegetatively by tip rooting, quickly forming daunting patches seemingly too tall and wide to tackle. We’ve all seen these conditions in old pastures, riparian areas and struggling plantations. Continue reading →

By Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension – Benton, Linn & Polk Counties

In previous installments of this series on the basics of herbicide use in weed control, I distinguished between foliar and soil active herbicides, describing foliar herbicides as those applied to the leaves or stems of plants to be absorbed and carried throughout the plant to affect control. In the previous post I began discussing foliar herbicides in more detail with an overview of glyphosate.

In this entry I will look at a group of herbicides called “growth regulators” that include some important foliar herbicides and popular weed and brush killers commonly used in forestry, agriculture and habitat restoration. Continue reading →

By Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension – Benton, Linn & Polk Counties

In my previous installment of this series on the basics of herbicide use in weed control, I distinguished between foliar and soil active herbicides. In this post I begin discussing foliar herbicides in more detail. Note: The attention given to herbicides in this series does not indicate an advocacy for their use but an acknowledgement that using herbicides presents some unique risks, and that landowners and managers need to know enough about them to make informed decisions on their use.

Foliar herbicides are applied to the leaves or stems of plants to be absorbed and carried throughout the plant to affect control. They are common and widely used to control annual and perennial herbs and also woody shrubs. Continue reading →

TreeTopics

Serving small woodland owners and managers in the Willamette Valley and northwest Oregon

Tag Archives: weeds

Have a holly-jolly holiday

Resources in the fight against weeds

Understanding vegetation in young plantations: It’s what they do

Knapweed

Use caution with spring tree release

It depends

Spring’s Scotch broom show is around the corner

Using foliar herbicides: Getting the bang for your buck

Understanding foliar herbicides – part 2

Understanding foliar herbicides – part 1

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