EVALUATION OF PLANT EXTRACTS FOR THE MANAGEMENT OF CERCOSPORA LEAF SPOT OF GROUNDNUT (Arachis hypogaeal L.)

Abstract

Cercospora Leaf Spot (CLS) caused by Cercospora arachidicola and Cercosporidium personatum of groundnut (Arachis hypogaea L.) is a major constraint against groundnut cultivation. In the wake of rising cost of chemical control, ecological-friendly methods of curbing CLS were studied. The main objective of the study was to determine the effectiveness of Desert date seed extract (DDSE), Neem seed extract (NSE), Jatropha seed extract (JSE) and Tobacco leaf extract (TLE) for the control of CLS disease of groundnut. The study comprised field survey, laboratory studies, green house and field experiments. Multi-stage sampling technique was used for the field survey. The field experiment employed a factorial experiment consisting of 18 treatments laid out in a Randomised Complete Block Design with four replications per treatment for two consecutive years. Farmers’ responses during the field survey showed CLS as a major constraint to groundnut production in Northern Region of Ghana. Farmers described the disease incidence as well as the disease severity to be above 50 %. In vitro studies indicated that aqueous DDSE, NSE, JSE and TLE at 100 g/l significantly inhibited mycelial growth of both Cercospora arachidicola and Cercosporidium personatum by 90.3 %, 80.8 %, 75.6 %, 54.5 % and 84.9 %, 73.3 %, 67.3 %, 59.4 % respectively. Pod yield was significantly more enhanced in plants treated with JSE, NSE, DDSE and Topsin-M, than those treated with TLE and the negative control plants for 2014 and 2015 cropping seasons with values ranging from 729 to 1095 and 931 to 1322 kg/ha respectively. For most of the parameters, DDSE produced similar results as Topsin-M followed by NSE and JSE. The adoption of DDSE, NSE and JSE as alternatives and better remedies to CLS disease control is recommended.