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United States Department of Agriculture

Agricultural Research Service

2012 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 are being isolated from diseased tissue from each weed. Both rust and leaf spot diseases were found on Chondrilla juncea. Two apparently new diseases of Cirsium arvense were also found and collected. Proof of pathogenicity has been completed for a fungus identified as Colletotrichum gloeosporioides collected from mile-a-minute (Persicaria perfoliata) around the Firtina (Storm) River outside of Ardesen, Turkey. This weed (mile-a-minute) is a serious invasive weed problem on the east coast of the U.S. and a report of this disease discovery is being published. Nine pathogens of field bindweed (Convolvulus arvensis) were evaluated for effectiveness in controlling this weed. These pathogens are being further evaluated alone and in combination at our quarantine facility. A visiting scientist from OMU is currently evaluating research with the goal of developing a mycoherbicide formulation for bindweed control. Field tests were also established in Turkey in collaboration with OMU. An epidemiology test has been established in 2012 on Rhaponticum repens (Russian knapweed) in the field at Ayas, Turkey with the fungus Boermia exigua. The fungus was multiplied in liquid culture. This was the first time this was done, and chlamydospores and mycelia, but not conidia, were formed abundantly. Aqueous suspensions of these cultures have been applied to R. repens plants in the field at Ayas, and collaborators from OMU and the Plant Protection Central Research Institute in Ankara, Turkey are collecting data on disease progress. Data from a previous epidemiology test with B. exigua on R. repens 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. It’s anticipated that data from the current (2012) field test should confirm these results and support release of the pathogen for biological control of Russian knapweed in the U.S. Another field test with the systemic rust fungus Puccinia punctiformis on Canada thistle (Cirsium arvense) is planned to be conducted at OMU in Samsun. Collaborators from OMU are currently collecting, in Haymana, Turkey, Canada thistle leaves diseased with the rust fungus Puccinia punctiformis to inoculate emerging rosettes of the weed in September, 2012. The objective of this test is to establish systemically diseased plants which will emerge in the spring of 2013. Tests in the U.S., Greece, and Russia have been successful in doing this, and these tests in Turkey, and 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.

Last Modified: 12/21/2014
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