- Author: Joseph DiTomaso
In 1997-1998, the big El Nino year in California, yellow starthistle (Centaurea solstitialis) (YST) infestations throughout the state were probably the largest that I have seen in my time in California. Not only were the infestations the densest, but the size of the plants often exceeded six feet tall. The reason for this is that water uptake by the roots of YST in the Sacramento Valley and surrounding foothills is highest between March and June in both shallow and deep soils. In contrast, water uptake by annual grasses is highest earlier in the season and only in shallow soils. During the El Nino year of 1997-1998, there was plenty of available soil water long after grasses had completed their life cycle and the extensive...
- Author: Joseph DiTomaso
Yellow starthistle (Centaurea solstitialis) (YST) is the most pervasive invasive and noxious weed in California. Previous work showed that YST uses substantially more water than forage annual grasses it typically displaces. Soil moisture was 20% higher in annual grass test sites compared to YST test sites. Because yellow starthistle is found (sometimes in very extensive stands) on millions of acres of California, it is possible that removal of the thistle could substantially increase groundwater recharge and subsequent surface runoff. This could greatly improve range conditions, wildlife habitat and water supply, especially in the Sacramento Valley where groundwater levels are generally still...
The Economist reports that Hungarian biologists have trained rabbits to preferentially eat common milkweed (Asclepias syriaca), an invasive plant (and a native to North America).
Elise Gornish, Josh Davy, Travis Bean, and I are testing the use of sheep for management of late-season invasive annual grasses. This trial is taking place at five sites at the Hopland Research and Extension Center – two with barb goatgrass, two with medusahead, and one mixed.
Treatments include grazing at boot stage (32 sheep-days on 324 m2), revegetation with native spp vs forage spp, and treatment with low or high rates of glyphosate at tillering, boot stage, and heading. The main plots are 18 m x 36 m including an 18 x 18 grazing enclosure and are replicated three times at each site. All treatments are crossed, for a total of 48 subplots in each main plot.
Grazing was conducted from mid-April to...
There is already a wall on our southern border, apparently, made of arundo (giant cane). This NY Times feature discusses US - Mexico cooperation in tackling the giant grass. Great pictures, too.
Arundo is also a big deal in California. Locally, it is one of the target species in the Delta Regional Areawide Aquatic Weed Project.