Response of Different Varieties of Isabgol against Downy Mildew Disease Severity under Variable Weather Conditions

Abstract

The downy mildew incited by Peronospora plantaginis Underwood is one of the economically important diseases of Isabgol (Patel, J. G., 1984; Yadav. et al., 2011). It is important to study and understand the role of different dates of sowing on the development of diseases and its eco-friendly management. The downy mildew symptoms appeared in four different varieties viz. GI-2, Niharika, H1-5, and HI-2009 sown on 28th Oct.(1st DOS) on 74-76 DAS whereas it was 52-54 days when sown on 12th Nov. (2nd DOS) and 51-52 days on the crop sown on 28th Nov.(3rd DOS). The maximum disease intensity of 62.77 % was observed during the second date of sowing and the least disease intensity was recorded on the third date of sowing (27.77%). The maximum average disease progression (7.50 cm) was observed on the first date of sowing and a minimum of 6.49 cm on third date of sowing. As the disease intensity increased AUDPC values also increased and these values were almost similar for all four varieties in relation to the date of sowing. The apparent infection rate increased to a greater extent from first date of sowing to second date of sowing thereafter, decreased during third date of sowing