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 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
Happy New Year!
Today I thought I'd attach a poster presentation from the recent 38th Annual Almond Industry Conference. The attached poster has some information on an ongoing research project in which we are testing thermal disinfestation as an alternative to soil fumigation for management of almond replant disease.
This is not especially a weed research project but has become an interesting area of research because of the high economic and environmental costs of soil fumigation. In second and later generation, trees can be affected by a variety of soil pests including fungal and bacterial pathogens, parasitic nematodes, and other yet-to-be-identified pests that can reduce orchard establishment and early...
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...
A few months ago I compiled some statistics on the acreage and value of tree and vine crops in California and put together a simple map of where the main production areas are located. One caveat to this map is that I only had access to land use data layers for the Central Valley counties and some Bay area and Central Coast areas. Therefore, this map does not show orchards and vineyards in Southern California or the Desert growing regions which are very important for some crops in the chart below the map.
These crops all fall under the label of "specialty crops" although some of them have fairly substantial acreage. One of the things I found most interesting in looking at these data compared to a few years ago is the...