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United States Department of Agriculture

Agricultural Research Service

2011 Annual Report

1a.Objectives (from AD-416)
(1) Collect, in Turkey, new pathogens of invasive weeds that are important in the U.S. and Turkey; (2) Determine the efficacy of the pathogens in infecting and damaging these weeds in the field in Turkey, and (3) Determine the host range of the pathogens among related non-target species.

1b.Approach (from AD-416)
New pathogens of invasive weeds in the U.S. and Turkey will be collected each year of this agreement. These pathogens will be isolated from diseased tissue either at FDWSRU or OMU or both. Studies on inoculation and infection efficacy of pathogens collected in Turkey in the past are currently ongoing in the containment laboratory at FDWSRU. Newly collected pathogens under this agreement will be studied in a like manner. Results of these studies will enable development of inoculation protocols that give maximum infection and disease development. Discovery of the best inoculation procedure and timing of inoculation to produce infected plants will enable instigation of epidemics in the field in Turkey. These protocols will be used for infection and host range studies in the field with the indigenous pathogen isolates from Turkey. These studies will be carried out simultaneously with inoculation and infection experiments.

Inoculum of pathogens collected in Turkey will be initially increased by our collaborator at OMU in Samsun, Turkey. The collaborator will inoculate host weeds to further increase inoculum for field tests. The collaborator will also locate fields infested with host weeds that can be used for our field tests. FDWSRU will supply the collaborator with seeds of some non-target test plants and seeds of other non-target test plants will be collected from Turkey.

Inoculation, monitoring, harvest, reisolation, and propagation of plants in and around OMU will not be problematic. Good facilities at OMU laboratories will help in accomplishing these activities. No hazardous procedures, materials, situations, or activities will be encountered. In short, successful infection, host range, epidemiology, and pathogen-spread studies in the native range of both the host and the pathogen are entirely feasible. Multiple successes, with different pathogens and hosts, within the anticipated three-year duration of the proposed project is very likely.

3.Progress Report

Diseases of several invasive weeds in the U.S. were collected in Turkey through collaboration with Ondokuz Mayis University (OMU) in Samsun. Pathogens were isolated from diseased tissue from each weed. Proof of pathogenicity has been completed for a Cercospora sp. collected from mile-a-minute (Persicaria perfoliata) growing around the Firtina (Storm) River in the Kackar Mountains outside of Ardesen (near Rize). Speciation of this pathogen is in progress. Other pathogens isolated included Alternaria cirsinoxia, a fungus once proposed as a control agent of Canada thistle. From field bindweed (Convolvulus arvensis), we isolated Septoria convolvuli and a Phoma sp. From Russian knapweed (Rhaponticum (=Acroptilon) repens we isolated Cercosporella acroptili, another fungus once proposed as a control agent. From cheatgrass (Bromus tectorum), we isolated a Septoria sp., and we will try further to identify this isolate to species, as there is already a Septoria sp. reported on cheatgrass in the U.S. Field tests were also established in collaboration with OMU. An epidemiology test was established on R. repens in the field at Merzifon, Turkey with the fungus Phoma exigua and a mycoherbicide formulation test with the same fungus on the same weed in Merzifon. For the mycoherbicide formulation test, the fungus was multiplied in liquid culture. This was the first time this was done, and chlamydospores, but not conidia, were formed abundantly. These chlamydospores will be formulated into an invert emulsion with a sucrose solution, surfactant, and crop oil following a procedure that was developed at FDWSRU in the 1990s. This formulation will be applied to R. repens plants in the field at Merzifon. Collaborators from OMU will collect data on disease progress in both tests. Data from the epidemiology test with P. exigua on R. repens that was conducted in 2010 in Ayas, Turkey showed that disease progress reached, on average, 86 percent diseased tissue by 65 days after inoculation and was predicted to reach 100 percent by 98 days after inoculation. Disease progress was most closely related to degree days above 18 C. Two other field tests were established on Canada thistle (Cirsium arvense) with OMU in Samsun and with Dr. Yusef Yanar (a new collaborator) from Galiosmanpasa University in Tokat, Turkey. Collaborators from both universities will collect Canada thistle leaves diseased with the rust fungus Puccinia punctiformis and inoculate emerging rosettes of the weed in September. The objective of these tests is to establish systemically diseased plants which will emerge in the spring of 2012. Tests in the U.S. and Greece have been successful in doing this, and these tests in Turkey, and also additional tests in the U.S., Greece, and Russia, will be additional replications in an international experiment to demonstrate that systemic rust disease can be routinely established.

Progress was monitored by e-mail and conference calls.

Last Modified: 11/26/2015
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