Foliar disease assessment of groundnut (Arachis hypogea L.) Varieties in forest/savanna transition agro ecology of Osun state, Nigeria
Groundnut (Arachis hypogea L.) is an important food and oil legume but its commercial production is often limited to some regions in Nigeria due to attack by pests and diseases. Seven varieties of groundnut released by the Institute for Agricultural Research Samaru and a local variety papa were assessed for their response to three fungal foliar diseases (early leaf spots, late leaf spots and rust) and insect pest damage under natural infection during the 2012 and 2013 cropping seasons in the forest/savanna transition agroecology of Osun State. All the tested varieties and the local check showed varying degrees of susceptibility to early leaf spot caused by Cercospora arachidicola, late leaf spot caused by Phaeoisariopsis personata and rust caused by Puccinia arachids. At the end of the on-farm trial, SAMNUT 10, 11 and 23 consistently showed the least severity of infection and favourably compared with the adapted local variety papa while SAMNUT 14 had the highest level of infection by both the early and late leaf spots throughout the period of observation. Rust was significantly (P<0.05) higher in SAMNUT 10 at 84 days after sowing but at the end of the assessment period, there were no significant (P<0.05) differences among the varieties in their response to rust infection as well as insect damage. The introduction of SAMNUT 10, 11 and 23 to farmers as well as improvement on the management of these foliar diseases may enhance the productivity of the crop in the region.