Location: Foreign Disease-weed Science Research2011 Annual Report
1. Improved methodology for host range determination. Determining host range of classical biological control agents has been a cumbersome process, often involving tests of 50 or more non-target species under conditions that make it difficult to predict results in the field. Recently ARS researchers at Ft. Detrick, Maryland, developed a procedure to generate best linear unbiased predictors (BLUPs), based on disease reaction and plant species DNA sequences, to determine the probable host-range, in the field, of plant pathogens for classical biological control of weeds. Results of host-range tests using this approach have been published in several articles, and the approach was presented at the Biological Control for Nature conference in Northhampton, MA. Comparison of BLUPs with actual damage on non-target plants indicated that BLUPs successfully predict damage by pathogens to non-target plants while having a lower probability of erroneously predicting a species not susceptible.
2. Successful initiation of in-field epidemics of Canada thistle rust. Canada thistle rust (Puccinia punctiformis) is either native or naturalized in all areas of the world where the weed occurs. Despite being studied for over 100 years the disease cycle had not been completely understood and this had prevented epidemics of the rust from being successfully initiated and used for biological control. Our research results indicate that inoculation of Canada thistle rosettes with teliospores or teliospore-bearing leaves in September (in the northern hemisphere) consistently leads to establishment of systemically diseased shoots the following spring and epidemics of the rust in subsequent seasons. These successes indicate that epidemics of the rust fungus can be initiated and have the potential to control Canada thistle. This has now been accomplished in Maryland and in Greece, and, through collaboration epidemics are being initiated in New Zealand, Russia, and Turkey.
Berner, D.K., Cavin, C.A. 2011. Finalizing host range determination of a weed biological control pathogen with BLUPs and damage assessment. Biocontrol. DOI:10.1007/S10526-011-9399-X.