- Author: Cari Koopmann Rivers
- Author: Steve Orloff
- Posted by: Gale Perez
The weather pattern this year in the Intermountain Region of Northern California has been radically different from what we have seen the previous 4 years. In most years, high pressure usually moves in periodically sending Pacific cold fronts farther north and giving us periods of warm dry weather. However, this winter and so far this spring high pressure has not dominated and we have been continually bombarded by cold fronts.
The frequent rains this winter and spring has resulted in changes in the weed spectrum. One weed we have seen a lot more of in this area is bur buttercup. Bur buttercup (Ranunculus testiculatus) has been widespread this spring and in some cases dense populations have been...
- Author: Richard Smith
- Author: Steven Fennimore
- Posted by: Gale Perez
Spinach is susceptible to weed pressure because it is produced on high-density 80-inch wide beds with 18 to 42 seedlines. There is no opportunity to cultivate the bed top so all weed control is accomplished by managing weeds in prior rotations, cultural practices, chemical weed control or hand weeding. Clipped spinach is mechanically harvested and must be kept as weed free as possible to reduce hand weeding costs. In the recent UC publication, Sample costs to produce and harvest organic spinach (Tourte et al, 2015 http://coststudies.ucdavis.edu/current/ ) hand weeding costs averaged $440 per acre. However, weeding costs can easily exceed $1,000 per acre in weedy fields, and...
- Author: Whitney Brim-DeForest
- Posted by: Gale Perez
We talk about herbicide resistance all of the time in California rice, but how does it evolve in a field? Understanding how herbicide management selects for resistant populations is an important part of preventing the problem from occurring in your fields.
We have many weed species in CA rice that are confirmed to be herbicide resistant. The major herbicide-resistant species are late watergrass, early watergrass, barnyardgrass, smallflower umbrella sedge, ricefield bulrush (roughseed), sprangletop, and redstem. For this illustration of how herbicide resistance evolves in a field, we use redstem as our example.
Year 1, Beginning of season: A population of redstem is found in a...
- Author: Sarah Morran
- Posted by: Gale Perez
Weed management strategies in California are as diverse as the cropping systems grown in it, which cover over 400 commodities and $47 billion in revenue (California agricultural production statistics, 2015). A challenge for growers across the state is to respond to the continuing adaptation, invasion and spread of weeds in their cropping systems. Many factors contribute to the ability of a weed to adapt itself to changing environments, and one focus of research in the weed group at UC Davis includes investigating the contribution that genetic plasticity plays in plant adaptability. Many weed species, particularly grasses, contain multiple genomes (polyploidy). Some plants (and humans) contain a single genome, which means that one...
- Posted by: Gale Perez
From California Ag Today by Patrick Cavanaugh, Farm News Director :: Aug. 8, 2016
Vigilant Seed Bank Reduction: Whatever it takes, don't let weeds set seed.
By Patrick Cavanaugh, Farm News Director
For the past 15 years, Robert Norris, professor emeritus and vegetable crops weed specialist, UC Davis Department of Plant Sciences, has continued to attend Weed Day each year at UC Davis and to contribute weed photography for
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