Influence of some inert diluents of neem kernel powder on protection of sorghum against pink stalk borer (Sesemia calamistis, Homps) in Nigerian Sudan savanna

摘要

Neem (Azadirachta indica) kernel powder (NKP) mixed 1:1 (weight basis) with some inert diluents (fine-sand, kaolin-dust, and saw-dust) were applied into the whorls of sorghum seedlings at 20, 30, 40, 50, days after sowing to provide protection against pink stalk-borer in field trials in 2002 and 2003. Carbaryl (Sevin 85) and untreated seedlings were used as check. Results showed that diluted NKP and carbaryl significantly (p <= 0.01) reduced leaf puncturing, dead hearts, stalk and peduncle boring below the untreated check. Although sole NKP caused scorching of leaves (phytotoxicity), this was not observed on plants treated with diluted NKP and absent with carbaryl. Mean yield increases above the untreated check for the two seasons were: 40.0% (NKP + fine-sand), 36.4% (NKP + kaolin-dust), 35.5% (sole NKP), 35.3% (NKP + saw-dust) and 29.4 % (carbaryl). Cost-benefit analysis shows that it was financially most beneficial to use NKP + fine-sand to control S. calamistis on sorghum in Nigerian Sudan savanna.