The effects of salinity stress on the development of Pythium blight of Agrostis palustris

Abstract

Salinity stress predisposed Penncross creeping bentgrass to cottony blight caused by P. aphanidermatum. Studies were conducted on the effects of salinity on the mycelial growth of P. aphanidermatum and on the growth of Penncross bentgrass. Mycelial growth increased significantly up to Ec levels of 7.1 ds/m when compared to mycelial growth at the control Ec levels of 0.5 ds/m. Plant growth was reduced to 50% of the control at Ec levels of 4.3 ds/m. 3-month-old Penncross bentgrass plants were inoculated and incubated at two differing temperatures. At 32 C, all plants died within 3 days regardless of salinity treatment. Rates of plant death were greatest at salinity levels over 2.8 ds/m. At 27 C, plants irrigated with water at Ec levels from 4.3 to 7.1 ds/m showed complete necrosis within 5 days, while treatments irrigated with tap water showed no disease symptoms.