Evaluation of neem seed extract, black soap and cow dung for the control of groundnut leaf spot at Samaru, Nigeria

Abstract

Trials were conducted at the Institute for Agricultural Research (IAR) farm, Samaru (Lat. 11° 11′N, Long. 07° 35′E) in 1999 and 2000 cropping seasons to evaluate cheap biorational products for the control of late leaf spots on groundnut. SAMNUT – 14(Ex – Dakar) a variety which is susceptible to leaf spots but commonly grown by resource-poor farmers was used for the study. The experimental design was a randomized complete block in which there were five treatments, neem (Azadirachta indica) seed extract, black soap and cow dung as biorational products, the recommended mixture of benomyl (Benlate 50% wp Du Pont) plus mancozeb (Dithane M-45) and an unsprayed check. Each plot consisted of five 75 cm ridges 5 m long and there were three replicates. The mixture of benomyl and mancozeb gave significantly better control of the leaf spots and higher yield than the others. Neem seed extract and black soap were not significantly different from each other in the disease control but different from cow dung extract which was not better than the unsprayed check. The black soap and cow dung scorched the groundnut leaves. There were significant high correlations between disease severity score, pod and haulm yields. Plants sprayed with neem seed extract gave yields higher than the plants that received other treatments, apart from the treated check.

Keywords:

• Neem seed extract
• Black soap
• Cow dung
• Late leaf spot
• Groundnut
• Nigeria

Acknowledgements

We acknowledge with thanks the technical support received from Messrs Jonathan Due and Dalhatu Abdu and the statistical analysis done by the staff of the data processing unit of the Institute for Agricultural Research, Samaru.