The Optimal Temperature and Dew Duration Affecting the Control of Water Chestnut by Epicoccosorus nematosporus
1998
Hong Yeon-Kyu | Shin Dong-Bum National Yeongnam Agricultural Experiment Station. RDA Milyang 627-130 (Korea Republic)
In greenhouse studies, control dfficacy of water chestunt (Eleocharis kuroguwai) by Epicoccosorus nematosporus was affected by temperature and dew condition. The appressoria were formed abundantly in the range of 20~28 degrees. When stem segments (30 cm long) of the water chestnut were inoculated with the conidial suspension of E. nematosporus, the mean conidial number attached amounted to 2,545 conidia. Out of 2545 conidia attached to the stem pidces, 1,733 (68%) conidia formed appressoria. When these stem pieces were treated for 24 hr at 28 degrees under dew condition, 183.1 (7.2%) lesions were formed 10 days after incubation. The time necessary for the death of the plants was about 25 days. Appressoria were formed at 15~35 degrees, but decreased rapidly in their numbers at the temperature lower than 10 degrees or at 35 degrees. The appressoria formation seemed to be depended on the dew duration, which was effective to the lesion formation and plant mortality. Under dew duration of 16~24 hr with temperature range of 25 degrees to 30 degrees, the weed control was increased up to 93.9%. There were no differences between the first and second or third dew treatments. A delat of 2 or 3 days in dew treatment did not increase the mortality of plants. For the use of E. nematosporus as a mycoherbicide of water chestnut, a conidial suspension should be applide when dew conditions are kept for 12 hr after inoculation.
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