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<p>One of the diseases threatening pasture health is brown leaf spot, caused by <i>Bipolaris yamadae</i>, recently reported in Brazil. The objective was to assess the effect of increasing nitrogen (N) doses on the behavior and severity of brown spot in <i>Megathyrsus maximus</i> cv. BRS Tamani. The experiment followed a randomized block design with four replicates. Treatments included five N doses (0, 50, 100, 150, and 200&#xa0;mg N dm<sup>-3</sup>) in the form of urea (45% N) diluted in water. Disease severity was estimated on 15 randomly selected leaves per pot at 7, 14, and 21 days after inoculation (DAI). At 14 DAI, the plants were cut 20&#xa0;cm above the ground to simulate grazing effects, and the final disease severity assessment was done at 21 DAI. Chlorophyll content in 15 fully expanded leaves per pot was estimated at 7 and 14 DAI. Yield traits were determined through cutting at 14 DAI. Fertilization increased growth, yield, chlorophyll index and brown leaf spot severity. The highest nitrogen dose at 7 and 14 DAI resulted in the highest brown spot severity while the dose of 168&#xa0;mg N dm-3 caused the highest severity at 21 DAI. Simulated grazing removed infected tissue and prevented an increase in severity at 21 DAI.</p>

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Behavior of Megathyrsus maximus cv. BRS Tamani to brown leaf spot, caused by Bipolaris yamadae, as a function of nitrogen fertilization doses

  • 期刊论文

  • 发表日期：

    2025年4月14日

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  • Hitalo Rodrigues da Silva,
  • Néstor Eduardo Villamizar Frontado,
  • Mariane Arce Tico,
  • Gustavo de Faria Theodoro,
  • Marcio Martinello Sanches,
  • Celso Dornelas Fernandes,
  • Gelson dos Santos Difante

摘要

One of the diseases threatening pasture health is brown leaf spot, caused by Bipolaris yamadae, recently reported in Brazil. The objective was to assess the effect of increasing nitrogen (N) doses on the behavior and severity of brown spot in Megathyrsus maximus cv. BRS Tamani. The experiment followed a randomized block design with four replicates. Treatments included five N doses (0, 50, 100, 150, and 200 mg N dm-3) in the form of urea (45% N) diluted in water. Disease severity was estimated on 15 randomly selected leaves per pot at 7, 14, and 21 days after inoculation (DAI). At 14 DAI, the plants were cut 20 cm above the ground to simulate grazing effects, and the final disease severity assessment was done at 21 DAI. Chlorophyll content in 15 fully expanded leaves per pot was estimated at 7 and 14 DAI. Yield traits were determined through cutting at 14 DAI. Fertilization increased growth, yield, chlorophyll index and brown leaf spot severity. The highest nitrogen dose at 7 and 14 DAI resulted in the highest brown spot severity while the dose of 168 mg N dm-3 caused the highest severity at 21 DAI. Simulated grazing removed infected tissue and prevented an increase in severity at 21 DAI.