Abstract
Sweet potato is an important root crop that serves as a staple food crop to the people in the South East, it was found to be heavily
threatened by leaf distortion disease. A field trial was therefore conducted during the 2024/ 2025 cropping season at the Research Farms
of Michael Okpara University of Agriculture, Umudike, South Eastern Nigeria to evaluate the potential effect of plant extracts including
Zingiber officinales (rhizomes), Carica papaya (seeds) and Moringa oleifera (leaves) on the control of bacterial leaf distortion of
sweetpotato (Ipoemea batatas Lam.) pathogen. The main aim was to isolate the causal organisms, identify and control the pathogens that
induced leaf distortion disease. The experimental design was Randomized Complete Block Design (RCBD) with three replicates. The
varieties used (Umuspo 1, Umuspo 2 and Umuspo 3) were sourced from National Root Crop Research Institute, Umudike (NRCRI).
Diseased sweet potato leaves were obtained randomly from the field during the cropping season and inoculated onto nutrient agar medium
for isolation and identification of bacterial pathogens. Some standard morphological and biochemical tests were also conducted. The
bacterial isolates obtained were sub cultured to obtain pure culture after incubation for 24hours and pathogenicity test was also conducted
to determine the pathogenic nature of the causal organisms. All data obtained were subjected to analysis of variance and the means
separated using Fishers significant difference at 5% probability using SASA 2009 Model. From the field experiment results showed that
all the plant extracts assessed reduced disease incidence and severity significantly at 5% probability when compared with the untreated
control. M. oleifera was found to be best in reducing incidence of bacterial leaf distortion (16.66%), as well as severity of leaf distortions
(2.87). However, extracts of C. papaya seed had the best performance (P ≤ 0.05) in terms of some growth parameters; vine leng th
(144.23cm), number of leaves (270.11), stem diameter (3.54cm) and number of branches across all the sweet potato varieties tested. Data
on C. papaya extracts compared favourable with those of extracts of Z. officinales on tuber yield at harvest (3.14kg). Laboratory results
obtained showed that four genera of bacteria were isolated: Pseudomonas (100%), Erwinia (80%), Staphylococcus (40%) and Bacillus
(20%). Pathogenicity test however proved the major organisms responsible for the leaf distortion disease of Sweet potato in Umudike were
two Pseudomonas and Erwinia spp. This study proves that the extracts of Z. officinales, C. papaya and M. oleifera have the potentials to
serve as biopesticides in the management of bacterial leaf distortion disease of sweet potato.
Key Words: Pseudomonas, Erwinia, extracts, botanicals, severity, pathogenicityjaerem NEW ANONABA, N. K., 2EFURUIBE. P. E
Menu