Issue link: https://read.dmtmag.com/i/96024
TL1301-proof 11/28/12 9:59 AM Page 1 TURF RESEARCH UPDATE MANAGEMENT, HOST PATHOGENICITY, AND IDENTIFICATION OF MAGNAPORTHE POAE, CAUSAL AGENT OF SUMMER PATCH ON ANNUAL BLUEGRASS TURF Summer patch, a root disease caused by the fungus Magnaporthe poae, is most pathogenic on annual bluegrass (Poa annua) golf course greens in North America. Disease symptom development can occur when the turfgrass is stressed, although M. poae thrives best under conditions of high air and soil temperatures, high soil moisture and high soil pH. Currently, summer patch disease is managed primarily through preventative chemical applications in conjunction with cultural practices. However, the appropriate method of fungicide application (e.g. application volume, additional irrigation) and the effects of various cultural practices on pathogen survival and disease development are not well known for the disease on annual bluegrass putting greens. In addition, pathogenicity and natural resistance in annual bluegrass ecotypes are not known in Ontario. Finally, proper diagnosis of this disease relies on visual observation of symptoms and signs on the PHOTOGRAPH OF THE COMPATIBILITY (THIS IMAGE) AND INCOMPATIBILITY (IMAGE RIGHT) OF VARIOUS M. POAE CULTURES. Sept 2012 - Update Molecular work for identification of Magnaporthe poae in Canada. Magnaporthe poae has been definitively identified in Canada. A disease note was submitted to the journal Plant Disease and was recently accepted for publication. Over one hundred (cup-cutter sized) greens samples exhibiting symptoms reminiscent of summer patch were collected from numerous southwestern Ontario golf courses from summer 2009 and 2010. Several roots of collected samples were covered with dark, ectotrophic runner hyphae and other structures characteristic of M. poae. Root sections were surface sterilized, plated on antibiotic medium and incubated at 28oC for approximately 2 weeks. A fungus with morphological characteristics similar to those of M. poae was consistently isolated and used to identify M. poae through molecular techniques (polymerase chain reaction or PCR) and Koch's postulates. These cultures have been maintained on fresh media through periodic re-culturing. DNA was extracted from the fungal mycelium of the collected isolates. To ensure PCR was successful, a small quantity of each PCR product was run on an agarose gel. As shown in Figure 1, seven DNA bands (~ 520-530 base pairs (bp) in size) were evident and appropriate for M. poae according to previously published literature and personal communication with Dr. H. M. Fouly. IMAGE CREDIT ALANNA SCHWAN & M. BASSORIELLO Project summary: PRELIMINARY PATHOGENICITY TRIAL IMAGE CREDIT XXXX (PHOTO COURTESY M. BASSORIELLO AND A. SCHWAN) roots, both of which can sometimes be misleading. The objectives of this study have been to identify M. poae, the cause of summer patch disease, in Canada, develop best management practices for summer patch, and determine host specificity and pathogenicity to gain a better understanding of disease development. Continued On Page 19 FIGURE #2 (AS REFERENCED IN ARTICLE) RESULTS OF 2010 FIELD TRIAL A) NO FUNGICIDE APPLIED B) AZOXYSTROBIN APPLICATION, NOT WATERED IN C) AZOXYSTROBIN APPLICATION, WATERED IN. WESTERN CANADA TURFGRASS ASSOCIATION 17 IMAGES CREDIT / COURTESY M. BASSORIELLO FIGURE 1. THREE DNA BANDS (~ 520Ñ530 BP) WERE PRODUCED THROUGH PCR. IMAGE CREDIT ALANNA SCHWAN & M. BASSORIELLO BY GRADUATE STUDENT: MELISSA M. I. BASSORIELLO PRINCIPAL INVESTIGATORS: KATERINA S. JORDAN J. CHRISTOPHER HALL