Abstract

Potato (Solanum tuberosum) is one of the most important industrial vegetable cash crops grown worldwide, with its tubers used for food. Potato production is constrained by pests and diseases, among which Phytophthora infestans is the most destructive, causing 50 to 70% yield loss under favorable environmental conditions. An experiment was conducted at the Institute of Agricultural Research for Development, Regional College of Agriculture, and Catholic University of Bamenda to assess the efficacy of plant extracts (Ocimum gratissimum and Zingiber officinale) and tissue culture cultivars in controlling potato late blight disease. Four potato varieties (Cipira, Dosa, Jacob, and Panamera) were used to produce tissue culture cultivars in the laboratory. These tissue culture cultivars were planted in the field alongside non-tissue culture cultivars in a randomized complete block design with four treatments, replicated three times. The plants were sprayed with two different plant extracts (Z. officinale and O. gratissimum), except for the tissue culture cultivars and the control field, which were not sprayed. Data were collected on disease incidence, severity, and yield. Infected potato plant leaves were used to isolate P. infestans in the laboratory. Plant extracts (Z. officinale and O. gratissimum) were tested in vitro for their effect on fungal mycelial growth. Results obtained from the field revealed a decrease in disease severity and an increase in yields in the fields treated with plant extracts and tissue culture cultivars compared to the control field. Plant extracts (Z. officinale and O. gratissimum) showed a reduction in mycelial growth of fungal isolates in vitro compared to the control, with the best results obtained from Z. officinale extract. Thus, O. gratissimum can be used to control potato late blight disease.

Key words: Potato, late blight, tissue culture cultivars, plant extract.