Appraisal of yield losses in pearl millet due to downy mildew pathogen (Sclerospora graminicola) in Nigerian Sudan Savanna

Abstract

Field trails were conducted at the Teaching and Research farm of the Faculty of Agriculture, University of Maiduguri during 2001, 2002, 2003 and 2004 cropping seasons to assess yield losses due to downy mildew on four pearl millet varieties namely Ex-Borno, SOSAT C-88, ICMV-IS-89102 and LCIC 9702. Split plot design was employed in which the four millet varieties were tested in the main plot, while the sub-plot factor consisted of five varying metalaxyl treatments of 0%, 25%, 50%, 75% and 100% designed to generate varying incidences of downy mildew. Results showed that incidence of downy mildew increased with increase in days after sowing (DAS) irrespective of percentage metalaxyl treatment and millet varieties. Results of grain yield loss showed that there was an increase in yield loss due to downy mildew with a decrease in the percentage of plants grown from treated seeds in 2002 and 2004. Grain yield was not taken during 2001 – 2003 due to early cessation of rains. The highest yield loss (33.8%) was sustained by ICMV-IS-89102 in 2002, while in 2004 the highest yield loss of about 29.6% was sustained by LCIC 9702. The lowest yield loss was recorded in SOSAT C-88 in the two years. The percentage mean yield loss for 2002 and 2004 indicate that LCIC had the highest yield loss due to downy mildew (31.61%) and the lowest was recorded in SOSAT-C88 (3.6%). There was no yield loss recorded at 100% metalaxyl treated crop while 45.6% of loss was recorded in 0% metalaxyl treated crops. Regression analysis of downy mildew incidence and severity on grain yield show that there was highly significant (P = 0.05) negative linear correlation between downy mildew incidence (r = 0.6272 – 0.9626) and severity (r = 0.7154 – 0.9148) on yield. Downy mildew incidence and severity correlated negatively on grain yield.