• The Korean Journal of Mycology
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• v.44 no.3
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• pp.196-200
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• 2016

Symptoms of summer patch were observed on Kentucky bluegrass (Poa pratensis L.) cv. "Midnight II" from mid-June in 2015 in Seoul, Korea. The symptoms appeared as leaf blight, root rot, and frog-eye patch, which are typical of summer patch. To identify the causal agent of these symptoms, a pathogen was isolated from diseased leaves and roots, and the cultural, morphological, and phylogenetic characteristics were analyzed. The isolate reached 50-60 mm on potato dextrose agar (PDA) after 10 days as a white-grey mycelium with septa, and became olive-green or brown from the center. Phialide-like structures were observed at the ends of hyphae, and conidia were rarely observed. A phylogenetic analysis was conducted based on large subunit (LSU) and RNA polymerase II large subunit (RPB1) sequences. According to this analysis, the isolated pathogen was confirmed to be Magnaporthiopsis poae. In a pathogenicity test, summer patch symptoms were observed at 20 days after inoculation using the same grass cultivar. This is the first report of summer patch disease caused by M. poae on cool season grass in Korea.

• Weed & Turfgrass Science
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• v.6 no.2
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• pp.151-156
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• 2017

Summer patch is the most serious disease at turfgrass field or golf course established with Kentucky bluegrass during high temperature season in Korea. Nevertheless, chemicals for the summer patch control are not yet registered in Korea. We isolated the pathogens from the turfgrass showing typical summer patch symptoms and identified as Magnaporthiopsis poae by using the internal transcribed spacer ITS1 and ITS4 sequences of rDNA. The inhibition rates of the pathogen were investigated for 10 fungicides. As results, the pathogen growth was suppressed when chemicals concentration increased and negatively correlated with incubation period with the chemicals. In triazole group, all chemicals (metconazole, myclobutanil, propiconazole and tebuconazole) treated showed the inhibition rates by 100%. Thiophanate-methyl showed the next highest inhibition effect against a summer patch pathogen. In strobilurin group, pyraclostrobin was the highest suppression effect compared with azoxystrobin and trifloxystrobin. Inhibition effect of fludioxonil and fluxapyroxad on pathogen was similar to the trifloxystrobin. Based on the results, triazole and carboxamide groups are strongly recommended due to the highest inhibition effect on the summer patch pathogen, Magnaporthiopsis poae.