|Sobhian, Rouhollah - RETIRED (USDA-ARS-EBCL)|
|Cristofaro, Massimo - ENEA C.R. CASACCIA|
Submitted to: California Invasive Plant Council
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2006
Publication Date: N/A
Interpretive Summary: Russian thistle (tumbleweed) is an important alien weed that has invaded about 100 million acres in the western U.S. Tumbleweeds invade fallow fields, clog irrigation systems, are hazardous to automobile traffic, spread wildfires and harbor insect pests that transmit viruses to many vegetable crops. Previously introduced biological control agents became established but are not providing sufficient control. We have evaluated several prospective new agents of these two weeds and have requested permission to introduce one of them. These new biological control agents should help reduce the populations of this weed to innocuous levels over extensive regions. Successful biological control would provide self-perpetuating long-term management of this weed, reduce the need to apply pesticides, and increase the productivity and utility of millions of acres in the western U.S.
Technical Abstract: We submitted a petition to the APHIS Technical Advisory Group (TAG) requesting permission to release the blister mite (Aceria salsolae) to control Russian thistle (Salsola tragus) and its close relatives was submitted to TAG in December 2004. Host specificity experiments conducted in the quarantine laboratory in Albany, CA indicate that the mite will not attack native North American Chenopodiaceae species (goosefoot family) nor commercial species such as beats, spinach or quinoa. A seed-feeding and stem-boring caterpillar, Gymnancyla canella, is undergoing a third year of host-specificity evaluation in Albany. Two interesting weevils (Anthypurinus biimpressus and Baris przewalskyi) have been discovered during foreign exploration in Tunisia and Kazakhstan.