EFFECT OF THREE SELECTED AQUEOUS PLANT EXTRACTS ON THE MANAGEMENT OF RICE BLAST (Magnaporthe oryzae) DISEASE UNDER TROPICAL FIELD CONDITION

Field experiments were conducted during the 2018 and 2019 cropping seasons at the Teaching and Research Farm, Federal College of Agriculture, Ishiagu, Ebonyi State, Nigeria, to determine the effects of foliar sprays of Morinda lucida, Piper guineense, and Xylopia aethiopica at a 7.50% w/v level of concentration on disease incidence and severity on three rice (NG/SA/DEC/07/0278, FARO- 19, and FARO- 21) accessions. Experiments were a 3 5 factorial arrangement fitted into RCBD with three replications. Data obtained on disease incidence, severity, and agronomic performance were subjected to analysis of variance while significant means were separated with the Tukey HSD test at p < 0.05. Assessment of blast disease showed that incidence, severity, and agronomic performance varied significantly with the plant extracts. The extracts sprayed on the foliage of the rice accessions significantly (p < 0.05) reduced the intensity of blast disease development in both seasons. Disease incidence ranged from 20.98 to 29.57% compared with 41.78 and 48.90% in the unsprayed plots, while severity ranged from 1.23 to 1.55 relative to 2.93 to 3.23 in the unsprayed plots in the 2018 and 2019 cropping seasons. Qualitative analysis showed that alkaloids, cyanogenic glucosides, tannins, saponins, flavonoids, phenols, and steroids were the secondary metabolites detected from the three plant samples. However, the quantitative results showed that there was a significant variation in the amounts of secondary metabolites present in each plant sample. In conclusion, the use of resistant cultivars is the best option in the management of blast disease. However, in the absence of resistant cultivars, foliar spray of P. guineense, M. lucida, and X. aethiopica at 7.5% w/v could help in the management of rice blast disease in the field and thus be recommended as a viable option for improved rice production.