Effect of Different Sowing Dates on Disease Initiation and Development of Roselle (Hibiscus sabdariffa L.) Leaf Spot Disease Caused by Coniella musaiensis Var. hibisci in Makurdi, Central Nigeria

摘要

The experiment was conducted mainly to investigate the effect of change in sowing dates on disease severity of Roselle (Hibiscus sabdariffa L) leaf spot caused by Coniella musaiensis Var hibisci, plant height, number of branches, number of fruits and calyx yield of Roselle (H. sabdariffa L). Five dates were selected with an interval of fourteen days (14) between the dates for two years (2003 and 2004) to determine the most appropriate time to sow the crop using two Roselle accessions; green (Acc₁) and red (Acc₃).The first date was determined by the establishment of the rains in the season. It was observed that change in sowing dates had significant (p = 0.05) effect on disease severity but not on plant height, number of branches, number of fruits and calyx yield. Plants sown on July 18/27 had lowest disease indices; and are thus the best and therefore recommended for cropping of Roselle.