- Author: Ben Faber
- Re-posted by: Gale Perez
From the Topics in Subtropics blog ∴ June 15, 2016
Researchers have now confirmed that six glyphosate-resistant weed species have been identified in California. Four have been known to exist for some time; they are horseweed (marestail, Conyza spp.), hairy fleabane, rigid ryegrass and annual ryegrass. To that list, junglerice and Palmer amaranth in the Central Valley have been recently added to the list. Additional weeds that have become more of a challenge to control and are on the suspect list are goosegrass and, in the central San Joaquin Valley, the summer grasses sprangletop and witchgrass.
There have never been a lot of...
- Author: Sarah Morran
- Posted by: Gale Perez
Each of us have the entire blueprint for our bodies contained in every cell, and the same is true of plants. This information is stored in the form of an extremely long molecule known as DNA (in human cells its length is ~6 feet). Studying and understanding DNA in plants has led to many advances in weed science including; the development of herbicide- tolerant crop varieties, understanding the causes of herbicide resistance and understanding the origins and spread of weeds in our environment.
Here in California, the weed science group at UC Davis is utilizing this technology to investigate glyphosate resistance that has been detected in California populations of junglerice. Junglerice is a summer grass weed present in many...
- Author: Cheryl A. Wilen
- Author: Guy B Kyser
- Author: John Madsen
In summer 2015, USDA-ARS and UC Davis Dept of Plant Sciences set up a water hyacinth control study with California Department of Boating & Waterways. The goal of the study was to determine the best of several different surfactants to pair with an aquatic-use formulation of glyphosate.
Aquatic weed trials are tricky compared to terrestrial trials, because the test sites are three-dimensional and they move around. In addition, water hyacinth is free-floating. In order to establish secure test plots, we built floating 1-m2 quadrats out of PVC pipe, swim noodles, and construction fencing.
On 31 July, we anchored the quadrats in open water within a sunken island in the Sacramento delta. Quadrats were...
- Author: Clyde Elmore
- Posted by: Gale Perez
Do weed populations change during a drought? Does drought favor certain species? Does annual or perennial species matter? During this four year period of drought in California, have they changed? What are the populations of annual and perennial weeds? With a limiting growth factor, in this case water, weeds become more prominent and which of them will or could disappear?
In urban landscapes, where turf grass areas are being renovated, or in non-irrigated land that has been farmed, but furloughed, or in non-cropped roadsides or wasteland, are we seeing life-cycle species shifts? Or is it that we see a loss or decreased competitiveness of annual species, thus perennial species can be observed?
I will give the example of...