I've made a couple posts about herbicide resistant weeds but I thought today would be a good time to go back to the basics for a moment. Occasionally, there is some confusion about the definitions of a "resistant" weed versus a "tolerant" weed. Although on one hand a definition seems like a pretty basic starting point, there was considerable debate about how to define herbicide resistance. The Weed Science Society of America (WSSA) [http://www.wssa.net] eventually settled on the following:
"Herbicide resistance is the inherited ability of a plant to survive and reproduce following exposure to a dose of herbicide normally lethal to the wild type. In a plant, resistance may be...
This is one part follow up to my previous post on glyphosate resistance and one part test of a tool to imbed articles in the blog.
The above frame has a 2008 report that Anil Shrestha, Kurt Hembree, and I wrote for California Agriculture on our glyphosate-resistant hairy fleabane work. You can click on it to open it in a full-screen reading pane.
I like this document hosting interface and may use it again. If you have problems viewing it in a particular browser, please let me know.
The article can also be downloaded here
I thought I'd followup on my post last week about herbicide resistant weeds with a little more detail on our recent (and ongoing) work on glyphosate-resistant horseweed (Conyza canadensis) which is also known as mare's tail.
In 2006 and 2007, we conducted research to determine the magnitude of the glyphosate-resistant horseweed problem in the Central Valley. The sampling was focused at that time in the Fresno area but included sampling as far south as Wasco and as far north as Marysville. We published the results of the initial project in 2009 (Weed Science 57:48-53) but the work has also led to several related projects which are ongoing.
In general, we found that:
1. Glyphosate-resistant horseweed was...
This is a reposting of an article I recently wrote for the California Weed Science Society Journal (also reprinted by Western Farm Press). The article is based on a presentation I made at the California Weed Science Society annual meeting in Visalia last January.
Here is a link to the whole issue where you can read several other articles: http://www.cwss.org/PDF/10CWSS%20Fall%202010.pdf
- Herbicide Resistance - An Evaluation of Hard-to-Control Weeds and a Discussion of What Might Be Coming Our Way
*This was an article that Doug Munier and I put together and tweaked for a couple orchard crop newsletters in summer/fall 2010. I thought I'd repost it here for posterity... Brad
Controlling Glyphosate-Resistant Weeds in Orchards with Rely:
Understanding the Issue and Managing the Solutions
Brad Hanson, UC Weed Extension Specialist, Davis
Doug Munier, UC Farm Advisor, Glenn, Butte, and Tehama Counties
By now, many tree fruit and nut producers in the Central Valley are familiar with glyphosate-resistant weed species. In the north Sacramento Valley, glyphosate resistant ryegrass is...