Assessing Irrigation Management for Its Effects on Disease and Weed Levels in Perennial Ryegrass
- Hongfei Jiang,
- Jack Fry and
- Ned Tisserat
Irrigation management is generally assumed to have a significant effect on turfgrass pest management, yet little research has been done in this area. This field study was conducted on perennial ryegrass (Lolium perenne L.) maintained under golf course fairway conditions in 1995 and 1996. Objectives were to evaluate water savings afforded by monitoring turf ET and adjusting irrigation accordingly; to compare preventive and curative pesticide control measures for control efficacy and amounts required; and to evaluate effects of two irrigation regimes on turf quality, weed infestation, disease incidence, and pesticide requirements. Turf received either daily irrigation of 7.6 mm of water regardless of prevailing weather conditions or irrigation to replace approximately 80% of atmometer-estimated evapotranspiration (ET) on 3 d weekly. About 200% more water was applied to daffy irrigated turf than to turf irrigated based on atmometer-estimated ET. Similar amounts of active ingredient were used on both fungicide schedules in 1995. In 1996, a curative fungicide schedule resulted in application of 64% less active ingredient than a preventive schedule. Daily irrigation suppressed brown patch (Rhizoctonia solani Kühn) injury by 9% in 1995 and 2% in 1996 but resulted in more than twice as many dollar spot (Sclerotinia homoeocarpa F.T. Bennett) infection centers in 1996. Irrigation treatment had no effect on smooth crabgrass [Digitaria ischaemum (Schreb.) Muhl.] or dandelion (Taraxacum officihale Weber) incidence.
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