Impact of some weather factors, plant age, plant growth stages and sowing date on population fluctuation of some sap-sucking pests attacking fenugreek plants

Abstract

st and March, 14 th at 41, 83 and 104 days from sowing date , respectively. In the second season, the peak numbers and account of aphids/20buds were recorded slightly differences. Pea aphid was insignificantly positive correlated with plant age for all sowing dates during two study seasons except for first date in the first season was significantly positive correlated. Also, pea aphid was the more dominant aphid species through three sowing dates during two seasons. Population fluctuation of T.tabaci had two, five and four peaks at the three sowing dates, respectively, in the first season. But in the second season T.tabaci recorded three, five and four peaks at first, second and third sowing dates, respectively. The three tested sowing dates arranged descending, where the T. tabaci population recorded as 7.29, 4.49 and 3.27 insects / 20 buds, respectively, in the first season. The general trend of T. tabaci infestation in the second season recorded gradually increasing, characterized with significant differences between vegetative, flowering and fruiting stages in the three sowing dates. Also the fruiting stage in the three sowing date is the most stage infested by T. tabaci.Statistical analysis of results for the two seasons was indicated that, the suitable date for fenugreek cultivation in Qualibia ,Governorate , Egypt Nov.,15 th where recorded mean numbers 1.67 ; 2.13 aphids / 20 buds and 4.49 ; 3.31 thrips / 20 buds in the first and second seasons , respectively, compared with other sowing dates. Also, the fruiting stages in the three sowing dates during two seasons is the most stage infested by T. tabaci followed by flowering and vegetative growth stages expect of, third date in the first season