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  1. Vol. 36 No. 6, p. 1631-1638
     

    * Corresponding author(s): pd9@umail.umd.edu
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doi:10.2135/cropsci1996.0011183X003600060036x

Brown Patch Severity in Perennial Ryegrass as Influenced by Irrigation, Fungicide, and Fertilizers

  1. Michael A. Fidanza and
  2. Peter H. Dernoeden 
  1. Dep. of Agronomy, Univ. of Maryland, College Park, MD 20742

Abstract

Abstract

Brown patch (Rhizoctonia solani Kühn) is a common and destructive disease of turfgrasses, but little information is available regarding its management by cultural practices. This 2-yr field study assessed the influence of irrigation, and N source alone or in combination with P and K on brown patch severity. Perennial ryegrass (Lolium perenne L. cv. ‘Caravelle’) was subjected to either morning or evening irrigation. Sodium nitrate, a quickly available non-soil reacting N source, was compared with sulfur-coated urea (SCU), a slowly available soil acidifying N source. Fertilizer treatments were applied three (May-September-October) and six (March-May-June-September-October-November) times annually, representing lower and higher N application rates, respectively. Forty-nine kilograms N per hectare were applied on each date for a total of 147 and 294 kg N ha−1 yr−1. Plots were split with one-half treated with iprodione [3-(3,5- dichlorophenyl)-IRN-( 1-methylethyl)-2,4-dioxo-1-imidazolidine-carboxamide)](3.1 kg ai ha−1) on an extended 21-d interval. In nonfungicide-treated plots, brown patch severity was consistently reduced with morning irrigation when compared with evening-irrigation. Non-fungicide-treated plots fertilized with SCU generally had lower blight levels than NaNO3-treated plots, regardless of N rate. In the second year, brown patch was more severe in plots treated with the high N rate, and P (72 kg ha−1 yr−1) and K (150 kg ha−1 yr−1) reduced blight for both N-sources in non-fungicide-treated plots. Sulfur-coated urea applied at the high N rate plus P and K resulted in blight levels equivalent to or less than low N. Fungicide-treated plots receiving the high rate of N from SCU plus P and K had the highest summer quality in both years. While low soil pH was weekly correlated (r = 0.352) with less blight, the slow N release characteristics of SCU were probably a more important factor in disease reduction than soil acidification. While brown patch severity was reduced by morning irrigation, SCU + P + K, and iprodione, an excellent level of summer turfgrass quality was not achieved using the extended fungicide application interval.

Scientific article no. A7743 and contribution no. 9064 of the Maryland Agric. Exp. Stn., College Park, MD 20742.

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