In mid-1996, we detected an unintentionally introduced seed-head ßy, Chaetorellia succinea (Costa), destroying seeds of yellow starthistle, Centaurea solstitialis L., one of the worst weeds in the western United States. In overseas studies, Chaetorellia succinea had been considered as a potential biological control agent for yellow starthistle, but had been rejected because of fears that itmigh...

Abstract Manure is a useful source of nutrients in olive orchards, but its effect on weed growth such an ecosystem has not been studied. A field experiment was conducted six-year old orchard (cv. Chondrelia Chalkidikis ) northern Greece to study the effects two forms fertilization (inorganic fertilizer and composted cow manure) weeds abundance flora composition (species diversity dominance). ra...

Spectral reflectance values of four canopy components (stems, buds, opening flowers, and postflowers of yellow starthistle (Centaurea solstitialis)) were measured to describe their spectral characteristics. We then physically combined these canopy components to simulate the flowering stage indicated by accumulated flower ratios (AFR) 10%, 40%, 70%, and 90%, respectively. Spectral dissimilarity ...

Conservation easements are an increasingly popular strategy for conserving biological diversity on private land. Long-term vegetation monitoring on conservation easements can provide critical information on persistence of biological diversity and abundance of invasive species. We sampled understory plant composition on five of The Nature Conservancy’s conservation easements in the Mt. Lassen fo...

The noxious weed yellow starthistle (Centaurea solstitialis L.) can be controlled effectively at the seedling stage with foliar application of the auxinic herbicides picloram or clopyralid. Although resistance to these herbicides is rare, a yellow starthistle biotype resistant to picloram and cross-resistant to clopyralid was observed in 1989 near Dayton, WA, in a pasture that had been subjecte...

Chronic ingestion of yellow star thistle (Centaurea solstitialis) or Russian knapweed (Acroptilon repens) causes nigropallidal encephalomalacia (NPE) in horses with an abrupt onset of neurologic signs characterized by dystonia of lips and tongue, inability to prehend food, depression, and locomotor deficits. The objectives of this study were to reexamine the pathologic alterations of NPE and to...