INFLUENCE OF WEATHER FACTORS ON POPULATION DYNAMICS OF GERBERA THRIPS (SCIRTOTHRIPS DORSALIS HOOD) AND ITS MANAGEMENT IN POT-PLANTED GERBERA

Abstract

Thrips (Scirtothrips dorsalis Hood) is a major sucking pest of gerbera (Gerbera jamesonii), yet information on its seasonal abundance, cultivar preference and management on this crop is scarce. Three experiments were conducted at the Hi-tech Horticulture Unit, Dr. Rajendra Prasad Central Agricultural University, Pusa (Bihar), during Rabi 2023–24. On pot-planted gerbera cv. Atlanta, thrips were present from the first standard meteorological week (SMW) of January to the last week of March, rising from 3.20 plant−1 (SMW 1) to a maximum of 26.07 plant−1 (SMW 10) before declining to 9.93 plant−1 (SMW 13). Weekly counts were negatively correlated with evening relative humidity (r = −0.718, P < 0.01) and positively, but only marginally significantly, with maximum temperature (r = 0.547, P = 0.053). Among ten cultivars screened in a polyhouse, mean thrips counts ranged from 12.63 (Soulmate) to 18.19 plant−1 (Brilliance); Soulmate, Stanza and Balance fell in the highly resistant group and Goliath, Atlanta and Brilliance in the highly susceptible group. In a field trial on cv. Goliath, two sprays of six insecticides reduced thrips by 21.3–74.2% over control; spinosad 45 SC (162 ml ha−1) was the most effective (74.2% and 47.6% after the first and second spray), followed by flonicamid 50 WG (65.6% and 44.3%), while dimethoate 30 EC was the least effective. Spinosad also gave the highest additional yield (15,392 cut stems ha−1 over control) and incremental benefit–cost ratio (7.38:1), followed by flonicamid (6.89:1). Regular monitoring, less-susceptible cultivars and alternation of spinosad and flonicamid at threshold are suggested for thrips management in gerbera.