Effect of staggered sowing on incidence of thrips, Thrips tabaci and purple blotch disease in onion

Field trials were conducted to know the most appropriate sowing date to minimize the incidence of onion thrips, Thrips tabaci and purple blotch caused by Alternaria porri in onion. The minimum thrips incidence was observed in 5th August sowing (7.41 numbers/plant) and in 15th August sowing (5.36 numbers/plant) during 2003 and 2004, respectively. The maximum thrips infestation was recorded in 5th July sowing (20.7 numbers/plant and 11.4 numbers/plant) during both the years. The highest disease intensity was recorded in early sown crop (June and July), followed by gradually declining disease intensity in later sown crop (August and September) in both the years. Highest bulb yield was obtained in 5th August (17.90 t/ha) and 15th August (19.80 t/ha) during 2003 and 2004, respectively. Hence, sowing during 5th to 25th August is advantageous for thrips and disease control with higher bulb yields.