Field insect pests and crop damage assessment of pigeon pea (Cajanus cajan [L.] Huth) grown under ratoon and in mixture with maize.

Mandag Dasbak1,Bonaventure Echezona1*, and Jerry Asiegbu1

The widespread adoption of cropping systems that are sustainable and environmentally friendly is vital for the macroeconomic survival of civilization. Intercropping could ensure stability of insect populations in a system. A 3-yr (2005-2007) field trial was therefore carried out in Nigeria under regular and ratooncrops to evaluate five recently developed pigeon pea (Cajanus cajan[L.] Huth) genotypes (ICPL 87, ICPL 161, ICPL 85063, ICP 7120, and ICPL 87119) from the International Crops Research Institute for Semi-Arid Tropics (ICRISAT) and one local variety for their relative performance and susceptibility to insect pests. The pigeon pea genotypes were in a mixture with two maize genotypes (Zea mays L., open-pollinated and hybrid) in regular crops for 2 yr (2005-2006) followed by a ratoon crop for 1 yr (2007). Termites (Odontotermes badius), crickets (Gymnogryllus lucens), and variegated grasshoppers (Zonocerus variegatus) were the crop’s seedling pests and caused minimal damage. Clavigralla spp. infestations were high at the reproductive stage causing 24% and 29% seed damage in regular and ratoon pigeon pea crops, respectively. Maize slightly suppressed insect pest incidence and damage to pigeon pea pods and seeds but significantly (P < 0.01) reduced grain yield in the regular pigeon pea crops in 2005 and 2006, although not in the 2007ratoon. The pigeon pea genotypes differed significantly (P < 0.05) in pest incidence at the podding stage in both the regular and ratoon crops and ingrain yield (P < 0.01) for the regular crop. Grain yield of the pigeon pea ratoon crops was about 60% of the regular crop. Farmers were recommended to adopt the ICPL 161 and ICPL 87 genotypes based on pest tolerance and high grain yield or as idiotypes in pigeon pea hybridization programs.

Keywords: Cajanus cajan, Clavigralla spp., cropping system, ratoon crops, regular crop.
1University of Nigeria, Department of Crop Science, P.O. Box 28 Nsukka, Nigeria.*Corresponding author (chezbon2001@yahoo.co.uk).