Effect of different mulch materials on the incidence and severity of okra mosaic virus (OMV) in okra

Abstract: The study was conducted from June to September, 2010 to assess the impact of different mulch materials on the incidence and severity of okra mosaic virus (OMV) in okra cv. 'LD 88-1' in Ibadan, Nigeria. The overall effects of the different mulches were assessed on the incidence and severity of OMV and the resultant effect on the number of pods and pod biomass. The mulches assessed in the field experiment were Azadirachta indica (neem) leaves, Eugenia uniflora (pitanga) leaves, Terminalia catappa (tropical almond) leaves, Panicum clippings and black plastic polythene. Positive and negative controls included hoe-weeded and unweeded plots, respectively. Results indicated that at 5 weeks after sowing (WAS), there was no significant difference in the OMV incidence on plants mulched with A. indica, E. uniflora and T. catappa with values ranging from 11.91 to 15.48% while a low virus incidence of 0.5% was recorded for the plastic mulched plants. The mean virus disease severity ranged from 0.7 to 4.0 on a scale of 1-4 scoring system with plastic mulched plants showing little or no symptom of OMV at 5 WAS. However, the plants on the unweeded plots were stunted with deformed fruits. Similar trend was observed at 7 WAS with plastic mulched plot having the least incidence and severity score while the unweeded plot has the highest OMV incidence and severity. Of all the mulch materials, plots mulched with Panicum produced the least yield values while plastic mulch induced the highest yield on the okra plants. Comparing the mean number of pods of weeded and unweeded control plots; the weeded plot produced average value of 23.0?0.1 pods/plant while the unweeded plot produced average of 12.0?0.15 pods/plant. The results obtained showed that mulches especially plastic are effective in controling okra mosaic virus.