The Speargrass (Imperata cylindrica (L) Beauv.) menace in Ghana: Incidence, farmer perceptions and control practices in the forest and forest-Savanna transition Agro-ecological Zones of Ghana

Surveys to determine farmers’ practices, perceptions and the incidence of speargrass were conducted in the forest and forest-savanna transition zones of Ghana in 1996 and 2000. Mean farm size was 1.2 ha, fallow and cropping length was 4.7 and 4.5 years, respectively, with a mean cropping intensity factor (CIF) of 49%. Speargrass had been present in the area for over 40 years and was perceived as the most noxious weed. Eighty- six percent of fields that relied on slash-burn method of land preparation had severe speargrass infestation. Infestations > 50% cover, mean density of 33 plants m-2 and shoot height range of 15–300 cm were observed on 60% of the fields. Fifty-one percent of farmers reported of inadequate level of control with current control practices. Glyphosate was applied onfields with > 50% speargrass cover. Speargrass becomes a problem after 3 years continuous cropping from fallow and, under severe infestation, most farmers abandon fields to natural fallow. A dense regrowth of Chromolaenaodorata is indicative of a speargrass-suppressed field. Follow-up weed control could be 3-6 times/season depending on initial land preparation, type of crop and/or level of infestation. Cost of weed control was 20–60% higher on speargrass-infested field ($71/weeding/ha) than on other fields, and weeding may take 20–25 mandays/ha. Farmers perceived average yield losses of 30–80$31–$84,$155–$414 and$272–$727 for maize, cassava and yam systems, respectively. Reductions in food quality due to the piercing nature of the rhizomes was also paramount

Response of False horn plantain to different plant densities and frequency of handweeding

The study, which was carried out at the Crops Research Institute, Kumasi, Ghana, from April 1992 to March 1995, aimed at determining (i) the optimum plant density of False horn plantain for maximum yield, and (ii) the optimum frequency of handweeding for economic returns. Results indicated that the optimum plant density for False horn was 1667 plants per hectare. At this density, the significantly highest bunch weight was 8.0 kg per plant. In Ghana, plantain is mostly sold as bunches and, therefore, bunch weight per plant rather than yield per hectare is of paramount importance. Handweeding, as weed control measure, proved to result in high economic returns. Keeping the field weedfree for the first 4 weeks followed by slashing every 12 weeks (4-IWP W 12-FUS) produced the highest economic returns of 71.5 per cent over the farmer's practice of weeding at only 12-week intervals from planting. Ghana Jnl agric Sci. Vol.32(2) 1999: 177-18