Role of weather factors in deciding the population of Diaphorina citri Kuwayama on curry leaf

Citrus psyllid, Diaphorina citri Kuwayama is known to cause serious damage to tender shoots, which in turn reduces the leaf yield in curry leaf plants. The pest is emerged as serious on curry leaf growing in and around Dharwad during the recent years. Thus it is important to understand the role of different factors promoting psyllid population on curry leaf plant. The changing weather parameters may also be one among few important factors promoting higher psyllid population. The influence of weather factors on citrus psylla, Diaphorina citri Kuwayama population on curry leaf (Murraya koenigii L.) was studied in 2018 and 2019. The average psyllid population ranged from 1.96 to 38.85 per 4 terminal shoots. There was no nymphal population from the 15th to 18th SMW during 2018 and 2019. The nymphal population peaked during the 37th SMW during both years. The adult population was recorded throughout the year with fluctuation. The adult population peaked (26.20 and 30.10 per 4 terminal shoots) during the 38th SMW (3rd week of September) in both years. Correlation analysis for both years indicated that maximum temperature exhibited a significant and positive correlation with the adult population. Similarly, evening relative humidity was highly significant and positively correlated with the nymphal population whereas, maximum temperature adversely affected the build-up of the nymphal population. The study is useful to find out the weak links of psyllid populations about abiotic factors that could be exploited to curb its infestation.