Management of Pod Borer Helicoverpa armigera Hubner) on Pigeonpea (Cajanus cajan (L.) Millsp.: Using Plant Density and Planting Dates for Increased Yield in Owerri. Nigeria

Abstract

: The potential of manipulating planting dates and plant spatial arrangement for management of the pod borers iHelicoverpa armigera Hubner) in early maturing pigeonpea (Cojanus cajan (L) Millsp) eultivar for increased yield was evaluated in a field study carried out in the Postgraduate Teaching and Research Farm, Department of Crop Science and Technology, Federal University of Technology, Owerri, Imo State in 2009 and 20 1 O. The experiment was laid out ina randomized complete block design with factorial arrangement ofthree planting dates (April 7, early-season cropping, July 7, mid-season cropping, and October 7, late-season cropping) and four plant spatial arrangement (15 cm x 35 em; 20 em x 40 em; 25 cm x 50 ern: 30 em x 60 em giving densities of 190,474; 125,000; 80,000; 55,556 plants ha' respectively). The treatments were replicated three times. H armigera larvae sighted from twelve plants from the three middle rows of each plot between 0630 and 0800 hours, during the podding stage were counted for assessment of larval population. The proportion of damaged pod/seed was weighed and the weight expressed as a percentage of the weight of the IOu-pod/sced sample. The results showed that pigeonpea planted at higher plant density of 190,474 plants ha' had higher population of H armigera and also recorded significant (p<0.05) pod and seed damage resulting in low values of seed yield (147.90 kg ha') in 2009 and (168.80 kg ha') in 20 I 0, when compared with pigeonpea planted at lower density of 55,556 plantsha' with seed yield (223.33 kg ha') in 2009, and (268.83 kg ha') in 20 IO. Plots planted in April gave the highest pod (444.00 kg ha'); and seed (295.00 kg ha') yield in 2009. The respective pod and seed yield values in 2010 were 328.40 kg ha' and 287.90 kg ha'. October planting had poor pod (64.00 kg ha'; seed yield 57.50 kg ha' in 2009 and pod/seed yield of60.40 kg ha'; 56.60 kg ha 'respectively in 20 10. Pod borer infestation was lowest in July planted plots and consequently pod and seed yields, 526.00 kg ha I and 353.20 kg ha'. respectively in 2009; and 499.50 kg ha I and 36X.00 kg ha I. respectively in 20 IO. and has higher compared to other planting dates. Therefore, tor increased yield of early maturing pigconpca that may ensure food security. July planting season with minimal H. annigcra loads should be adopted inOwcrri. Nigeria.