Comparative abundance of major pests of important ornamental crops in relation to crop phenology

Abstract

Investigation entitled “Comparative abundance of major pests of important ornamental crops in relation to crop phenology” was carried under protected cultivation (polyhouse) at Navsari Agricultural University, Navsari, Gujarat during 2016 - 2018. No population of bud borer, Helicoverpa armigera larvae was observed on rose during the course of investigation while, thrips Frankliniella schultzei population varied from 0.44 to 42.70 per plant (10.63±11.68) indicating highest (42.70/plant) and lowest populations (0.44) at 42 and 18 SMWs, respectively whereas, no thrips were noticed during 4-8 and 19-26 SMWs. Thrips population was observed at all the three crop stages of rose being highest at flowering stage (19.32 + 17.51) indicating significant positive (r = 0.3119) correlation with crop stage. Mite population on rose varied from 1.89 to 11.89 per plant on 2 cm2 leaf area (6.32 + 2.58) indicating its peak (11.89) at 31 SMW and lowest level (1.89) at 51 SMW. Highest mites (6.45/2 cm2 leaf area) were noticed at vegetative stage of the crop indicating negative correlation with crop stages (r = -0.0687). Thrips, F.schulizei population on gerbera varied from 0.04 to 46.54 per plant (11.79 + 13.26) indicating highest density (46.54) at 42 SMW and lowest (0.04) at 18 SMW. Highest thrips (17.34 + 16.44) were noticed on gerbera at the flowering stage indicating significant and positive (r = 0.3175) correlation with crop stages. Likewise, mite population on gerbera peaked at 31 SMW (12.83 /plant on 2 cm2 leaf area) while, it remained lowest (2.70) at 51 SMW. Mite population at all the three crop stages was more or less the same being slightly higher (7.33 + 2.88) at stalk formation stage indicating persistent nature of the mite pest which in turn exhibited negative but non-significant correlation (r = -0.0733) with crop stages. In case of anthurium, no thrips population was observed at any stage of the crop while, mite, Tetranychus urticae population varied from 0.25 to 1.43 mites per 2 cm2 leaf area per plant indicating its highest (1.43) and lowest levels (0.25) at 1 and 7 SMWs, respectively. Mites were observed only during the vegetative stage of crop growth barring solitary appearance during flowering stage at 5 SMW which in turn indicated negative but non-significant correlation (r = - 0.0344) with the crop stages. No pest was observed on orchid during the current investigation except solitary appearance of blossom midge (1.88/plant) at 30 SMW (bud formation stage). Blossom midge population on orchid also exhibited positive correlation with crop growth (r = 0.0422).