Spray schedule for the management of Alternaria blight and white rust of Indian mustard (Brassica juncea) under different dates of sowing

Abstract

A field experiment was conducted during 2002-03 and 2003-04 to develop spray schedule(s) for the management of blight, caused by Alternaria brassicae (Berk.) Sacc., A. brassicicoIa (Schwein) Wiltshire, and white rust caused by AIbugo candina (Pers. ex. Lev.) Kunze, in Indian mustard [Brssica juncea (L.) Czem & Coss.] sown on 15 October, 30 October and 15 November. Fifteen October sowing resulted in least leapblight, pod blight and white rust intensity with highest 1000-seed weight and yield. Three consecutive sprays of mancozeb 75 WP (0.2%) d fortnightly intervals, beginning disease initiation resulted in least leaf blight and pod blight intensity. This spray schedule with benefit:cost ratio of 4.35, 3.98 and 3.33, respectively under first second and third dates of sowing and highest net returns of Rs 6 3 16 and Rs 5 6 12 for the first and second dates provedmost economical. Highest 1 000-seed weight and yield, under all the dates of sowing however were given by the spray schedule having 2 consecutive sprays of mancozeb followed by third of ridomil MZ 72 (0.25%). It gave highest return of Rs 6 492 under third date of sowing. All the spray schedules proved more economical when applied to seed crops.