Seasonal incidence of fall armyworm, S. frugiperda in maize

Abstract

The activity of FAW in maize was observed throughout the crop period during rabi, 2019-20 and 2020-21. The activity commenced (3.50 & 4.00 larvae/10 plants; 58.33 & 60.00% plant damage, respectively) in the 3rd week of November (46th SMW) and continued till the 2nd week of February (6th SMW). After the appearance of FAW, it gradually increased and reached its peak (7.67 & 7.83 larvae/10 plants; 81.67 & 83.33% plant damage, respectively) during the 4th week of December (51st SMW). In the following week, it gradually declined and reached 1.67 and 1.83 larvae per 10 plants along with 58.33 and 60.00 per cent of plant damage during the 2nd week of February (6th SMW), respectively. The per cent cob damage began from the 3rd week of January (2nd SMW) and it was 23.33 and 26.67 per cent during 2019-20 and 2020-21, respectively. Thereafter, it continuously increased and lasted up until the crop was harvested on the 2nd week of February (6th SMW), when it hit 55.00 and 58.33 per cent for both years, respectively. The incidence of FAW exhibited a highly significant positive association with minimum temperature and evening relative humidity. The maximum temperature showed a significant positive correlation, whereas rainfall and evaporation showed a significant negative correlation with the population build-up of FAW.