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This article in AJ

  1. Vol. 83 No. 4, p. 670-677
     
    Received: May 15, 1989


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doi:10.2134/agronj1991.00021962008300040005x

Summer Patch and Kentucky Bluegrass Quality as Influenced by Cultural Practices

  1. D. B. Davis and
  2. P. H. Dernoeden 

Abstract

Abstract

Summer patch, caused by Magnaporthe poae Landschoot and Jackson, is among the most destructive diseases of Kentucky bluegrass (Poa pratensis L.). While fungicides may reduce disease severity, information regarding the impact of cultural practices on this disease is unavailable. Hence, the objectives of this field investigation were to examine the effect of irrigation practice [light frequent (LF) versus deep infrequent (DI) irrigation); mowing height (3.8 versus 7.6 cm); and N source (urea, sulfur coated urea, ammonium chloride and sodium nitrate) on summer patch incidence and severity, and turf quality. The study was conducted on a stand of ‘S-21’ Kentucky bluegrass grown on a Chillum silt loam (fine silty, mixed mesic Typic Hapludult). The effects of these cultural parameters on root biomass, total nonstructural carbohydrate (TNC) content of crown tissue, leaf tissue N, and soil temperature also were evaluated, and their relationship to summer patch incidence and severity is discussed. Turf maintained at 7.6 cm was damaged less by summer patch, exhibited better overall quality, and stored higher TNC levels than turf maintained at 3.8 cm. In 1987 when disease pressure was extremely high, turf subjected to DI irrigation and maintained at 7.6 cm exhibited higher quality and lower summer patch incidence than any other irrigation-by-mowing-height combination. Severely damaged turf allowed to grow from 3.8 to 7.6 cm recuperated more rapidly from disease injury than turf maintained continuously at 3.8 cm. Turf fertilized with sulfur coated urea generally exhibited best quality in 1987 and 1988, and was injured less by summer patch in 1987.

Scientific Article no. A4960 and Contribution no. 8003 of the Maryland Agric. Exp. Stn., Dep. of Agronomy, Univ. of Maryland.

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