Varietal Differences on Incidence and Severity of Leafspot Disease of Groundnut

Abstract

Groundnut (Arachis hypogaea) is a well known oil-seed crop grown mostly in the savannah areas of Nigeria, and
with little cultivation in the forest south. Groundnut comprise of two widely used varieties. The spreading type is
more modulated than the erect. Groundnut is affected by diseases such as fungal, viruses and bacterial diseases.
The two principal species of fungal leafspot diseases being the Cercospora arichidicola which cause early leafspot and
Cercosporidum personatum which cause late leafspot. These are distinguished by the size and shape of the conidia
and the number of Septa. Analysis shows a significant difference in leafspot disease severity at 8 weeks of plant
age, leaf area production at 6 and 10 weeks of plant age, Biomass, Pod length, Pod size index and 10-pods weight
although there is no significant difference on plant depth in the two varieties. Plant densities recorded a significant
difference on the severity of leafspot diseases at 4, 8 and 12 weeks on early maturing variety but the leaf maturing
only showed a significant difference of 12 weeks of plant age. Interaction of plant depth and density are significant
in the two varieties but early maturing is significant, in plant height at 4 and 10 weeks. Erect type recorded lower
disease severity and percentage defoliation of 0.8 and 76.3% while spreading type (late maturing) 0.82 and 89.6%
were high.