Date of Award

12-2006

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Plant and Environmental Science

Advisor

Martin, Samuel B

Abstract

Seashore paspalum is a new turfgrass being evaluated in the southeastern United States due to its tolerance to salinity and sodicity. Rhizoctonia solani AG 2-2 `LP` was isolated from seashore paspalum exhibiting symptoms typical of Large Patch (LP). The disease was identified based on field symptoms, lesions on the plant, and the fungus identified based on cultural characteristics, multinucleate hyphal cells, and anastomosis with a known tester isolate of R. solani AG 2-2 `LP` from zoysia grass.
Two research putting greens were constructed in 2005 located in Florence, SC and near Bluffton, SC and planted to seashore paspalum cultivars SeaIsle 1, SeaIsle 2000, SeaIsle Supreme, Sea Spray, SeaDwarf, Aloha and Salam, with 3 blocks at each location. Sub-plots were treated with fungicides three times in the fall 2005 on 21 day intervals, at low label rates. Epidemics of LP occurred at both locations in fall and winter months. There were no cultivar _ fungicide interactions at either location. All cultivars were affected by LP and severely damaged in non-fungicide treated plots. The most susceptible cultivar at Bluffton was SeaIsle I and at Florence SeaIsle 2000. SeaIsle Supreme, Aloha and SeaSpray were damaged less. Fungicides giving the best control were azoxystrobin and pyraclostrobin; thiophanate methyl performed well at Florence but not at Bluffton.
An irrigation quality experiment was conducted in the greenhouse to evaluate the salinity tolerance of the seven cultivars to five levels of irrigation water salinity from 0.5dS/m to 30 dS/m of electrical conductivity. Significant differences in turf quality, turf density and leaf firing were found as salinity increased. The highest levels of salinity reduced quality, density and increased leaf firing to unacceptable levels.
We conclude that LP is a major disease of seashore paspalum in transition zone climates and will require fungicide treatment for acceptable quality and that there is a limit to the irrigation water electrical conductivity that seashore paspalum can tolerate with no deterioration in turf quality.

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