Determination of the economic threshold of whitefiy,Bemisia tabaciGenn., on American cotton in the Punjab

Studies were conducted to determine the economic threshold of whitefiy, Bemisia tabaci Genn. on cotton at the Cotton Research Station, Muktsar during 1981 to 1983. The results show that the spray on American cotton var LH 372/F 414 against whitefiy be initiated as and when a population of 6 to 8 whitefiy adults/leaf is noticed from mid July onwards or when the middle canopy leaves show yellow spots and are sticky by touch. The average reduction in yield due to whitefiy attack were 8% and 10% in the first and last years and 31% the maximum in 1982–83.