Impact of Planting Date, N. Fertilization and Infestation Rate by Cowpea Worm Etiella zinckenella, (Treitschke) Treated with Trichogramma evanescens, (Westwood) on Dry Seed Yield of Cowpea Vigna unguiculata, L.

Abstract

Two-field experiments were carried out during two-successive summer-seasons (2015-2016) at Vegetables-Research-Farm, Kaha-Qalubia-Governorate, Egypt. Study aim to investigate three-dates effect of sowing (1st-April, mid-April and 1st-May) and two-mineral nitrogen recommended doses 100 and 50% under field of Etiella zenckenella controlled by (Trichogramma),and their interactions on growthing, nutrient concentration, yield and components of cowpea-plants (Vigna unguiculata L.). Obtained results showed, first sowing-date was desirable significant effect on growth, yield and components i.e. seed number/pod, weight 100-seeds and seed yield/feddan in both seasons. Also, 1st-sowing-date×60kg/fed N-dose with Trichogramma releasing recorded, highest vegetative growth characteristics, yield traits, highest nitrogen concentration, phosphorus, potassium and protein-content in seeds. Also, full nitrogen dose (60kg/Fedd.) along with Trichogramma utilization at all sowing-dates gave best growth parameters and seed yield. Infested%/pods decreased after Trichogramma treatments with about 54.1, 42.4 and 39% in 1st-season and 82.3, 82 and 78.5%, in 2nd, at 1-April, Mid-April and 1-May, when compared with control. However, significant differences in infested%/pods were observed between three planting-dates. Moreover, infestation% increased by delaying planting-date in both seasons. No significant differences were found in percent reduction of % infested pods between 1st and 2nd planting-dates of cowpea treated with Trichogramma. Itcould be recommended release of egg parasitoid T. evanescens combined with select 1-April planting-date against E. zinckenella.