- Author: Marie Jasieniuk
Horseweed and hairy fleabane are closely related annual weeds that are widespread in Central Valley orchards and vineyards where many populations have evolved resistance to glyphosate. Interestingly, however, the geographic distribution of glyphosate resistance differs markedly between the two weeds.
A survey of 42 horseweed populations across the Central Valley in 2010 showed that glyphosate-resistant plants were abundant across the southern part of the Valley but that horseweed in the northern part of the Valley was still largely susceptible. In contrast, a survey (unpublished) of 35 hairy fleabane populations in the same general...
- Author: Douglas J Munier
Glyphosate resistant ryegrass has been a persistent problem since appearing in almond orchards in the Sacramento Valley in the late 1990’s. It is a winter annual weed, but under irrigation it can germinate any time of the year. This year round germination pattern wasn’t noticeable in the Sacramento Valley when it was effectively controlled by glyphosate. Summer and early fall germinating ryegrass plants are particularly difficult to control at the typical November to December herbicide timings because they are larger established plants at the time of application.
Pre-emergence herbicides are a good way to deal with this extended germination period. June/July pre-emergence herbicide treatments...
This is a repost (with permission) of an article by Mark Bolda (UCCE Santa Cruz Co) from April 27, 2012. The original post and the Strawberry and Caneberry blog can be found at: http://ucanr.org/blogs/blogcore/postdetail.cfm?postnum=7362
by Mark Bolda:
This comes up a couple of times every year so it is worth reviewing and certainly adds value to our catalogue of plant disorders on these berry blogs.
The following plant sample of a proprietary...
- Author: Gale Perez
Follow-up to Lynn Sosnoskie's 3/6/2012 UC Weed Science blog entry (http://ucanr.org/blogs/blogcore/postdetail.cfm?postnum=6967)
Here's the NPR story "Farmers Face Tough Choice On Ways To Fight New Strains Of Weeds"
- Author: Douglas J Munier
Previously in this blog Brad Hanson discussed some of the research Kent Brittan (UCCE Yolo) and I have done with Roundup Ready canola as a crop and then evaluating it as a weed because of its seed dormancy characteristics. We published an article on the weediness potential of Roundup Ready canola in California this past January in the Journal of Environmental Science and Pollution Research.
Here's the abstract from the article:
Abstract: Canola which is genetically modified (GM) for tolerance to glyphosate has the potential to become established as a new glyphosate resistant weed, thus reducing the effectiveness of glyphosate. Volunteer from dormant canola seeds produced thousands of plants per acre...