Piecemeal versus one-time harvesting of sweet potato in north-eastern Uganda with special reference to pest damage

AbstractIn north-eastern Uganda, the sweet potato crop of small subsistence farmers is severely affected by many pests, including (rough) sweet potato weevils, nematodes and millipedes. Field experiments with sweet potato (Ipomoea batatas (L.) Lam.) were conducted at Arapai Station in Soroti District, northeastern Uganda in three consecutive seasons to study the differences between the indigenous practice of harvesting piecemeal in combination with storage ‘in-ground on plants’ and one-time harvesting after crop senescence, with special reference to damage caused by sweet potato weevils (Cylas spp.), rough sweet potato weevils (Blosyrus spp.), millipedes (Diplopoda) and nematodes. The area has two rainy seasons per calendar year, the first one with long, reliable rains and the second one with short, unreliable rains. Severe sweet potato weevil damage in the vines was responsible for the mortality of 46% of the plants in Experiment 1, which was carried out during the first rainy season. Starting 3 months after planting (MAP), sizable storage roots could be harvested, although their number and weight declined after 4 MAP with piecemeal harvesting. The highest storage-root yield (17.8 Mg ha−1) was found in Experiment 2 (second rainy season) at the final harvest. The yield of storage roots stored ‘in-ground on plants’ during the prolonged dry season (Experiment 3) was very low compared with the yields of Experiment 1 (first rainy season) and Experiment 2 (second rainy season). Sweet potato weevil damage of the storage roots was significantly less with piecemeal harvesting than with onetime harvesting, and piecemeal harvesting also increased the quality of the storage roots for human consumption and commercial purposes. However, with piecemeal harvesting the rough sweet potato weevil (Blosyrus spp.) caused more storage root damage than with one-time harvesting. No statistically significant differences between the two types of harvesting were found for damage caused by nematodes or millipedes. It was concluded that piecemeal harvesting of sweet potato storage roots contributes to the control of sweet potato weevil in both vines and storage roots and hence improves the quality of the harvested roots. As rainfall distribution affects the population dynamics of this weevil this method can only be used during a limited period of the year

Are millipedes a pest in low-input crop production in north-eastern Uganda? : farmer's perception and experimentation

These studies included: (i) Field survey on farmers’ knowledge on sweet potato production and perception of millipede infestation; (ii) Field assessment of pests in sweet potato and other major crops conducted in the planting seasons of 2000 – 2002; (iii) Feeding activity of the East African millipede Omopyge sudanica Kraus, based on no-choice laboratory experiments, and (iv) Comparison of the indigenous cultural practices of piecemeal harvesting and storage roots ‘in-ground on plants’ with one-time harvesting after crop senescence in trials conducted in the planting seasons of 2002 – 2003. There was inadequate information about millipedes in general and possible control strategies in East Africa. Therefore a literature study was also done to gain more knowledge about this animal

Feeding activity of the East African millipede Omopyge sudanica Kraus on different crop products in laboratory experiments

Millipedes can cause considerable damage in the production of sweet potato and some other crops in East Africa. Quantitative information on intake of crop diets by and body weight gain of millipedes was collected in short-term no-choice feeding activity laboratory experiments conducted in north-eastern Uganda using female millipedes of the species Omopyge sudanica. Diets consisted of sweet potato and cassava storage root material, groundnut seeds, or maize grains. Differences in intake and body weight gain between diets were not statistically different. The consumption index, i.e., the ratio between intake and body weight gain, was significantly higher for sweet potato than for most other diets. The efficiency of conversion of ingested food, i.e., 100 × the ratio between body weight gain and intake, was significantly lower for the root crops ? especially sweet potato ? than for the grain crops. The research showed how difficult it is to obtain reliable, quantitative data on the feeding habits of millipedes, but also illustrated that O. sudanica can cause harm to crops in north-eastern Uganda and elsewhere in East Afric

Farmers' information on sweet potato production and millipede infestation in north-eastern Uganda. II. Pest incidence and indigenous control strategies

Sweet potato (Ipomoea batatas (L.) Lamk) is an important staple food for the people of north-eastern Uganda. Crop yields per unit area are low partly because of biological constraints, including pests like millipedes. The objective of this study was to generate information on pest incidence and control strategies of millipedes by interviewing farmers in different districts. The respondents associated the dying of planting material with drought. However, millipedes also damaged planting material planted early in the rainy season. The sweet potato butterfly (Acraea acerata, Lepidoptera: Nymphalidae) was present, but considered by farmers to be insignificant. Measures to control sweet potato pests, like sanitation, were hardly implemented and insecticides were not used at all. Most respondents performed piecemeal harvesting. Whenever farmers delayed the harvest, they risked severe damage of their sweet potato crops by weevils (Cylas spp., Coleoptera: Curculionidae) and millipedes (Diplopoda). Millipedes pierce and tunnel the storage roots, especially when harvesting is delayed. The farmers did not mention specific natural control agents for millipedes. Knowledge about pests was generally limited, so control strategies were poorly developed, understood and applied

Pest damage in sweet potato, groundnut and maize in north-eastern Uganda with special reference to damage by millipedes (Diplopoda)

The morphology and rumen fermentation kinetics of the maize cultivars (Zea mays L.) Vitaro and Volens were investigated in detail throughout their growing period as a first step towards understanding the relation between plant characteristics and cell wall fermentability of forage maize. Vitaro is known to have a 9% higher whole plant organic matter digestibility than Volens. Leaf and internode development, fresh (FW) and dry weight (DW) per plant and dry matter content (DMC) of leaves, internodes and developing ears, as well as rumen fermentation characteristics of the stem, were monitored during two seasons. Vitaro plants had a larger final leaf area than Volens plants but their number of leaves (and internodes) was the same. Fully developed Vitaro internodes were shorter and thicker than Volens internodes, resulting in a shorter plant for Vitaro. After anthesis, FW and DW of individual internodes did not vary significantly throughout the growing period. Whole plant FW increased sharply after anthesis, which was associated with the development of the main ear. In both cultivars, DMC of the whole plant more or less doubled between anthesis and harvesting. Vitaro had a higher DW per plant than Volens, but not a larger ear proportion. In rumen fermentation tests on whole stem samples, using the gas production technique, gas production after 72 hours and Tilley & Terry digestibility were significantly higher for Vitaro than for Volens, indicating a higher total degradability for Vitaro. It was concluded that the two cultivars form a suitable model system for studying the causes of differences in rumen fermentation between maize roughages

Farmers' information on sweet potato production and millipede infestation in north-eastern Uganda. I. Associations between spatial and temporal crop diversity and the level of pest infestation

Sweet potato (Ipomoea batatas (L.) Lamk) is an important staple food for the people of north-eastern Uganda. Crop yields per unit area are low partly because of biological constraints, including pests like millipedes. The objective of this study was to generate information on pest incidence and control strategies of millipedes by interviewing farmers in different districts. The respondents associated the dying of planting material with drought. However, millipedes also damaged planting material planted early in the rainy season. The sweet potato butterfly (Acraea acerata, Lepidoptera: Nymphalidae) was present, but considered by farmers to be insignificant. Measures to control sweet potato pests, like sanitation, were hardly implemented and insecticides were not used at all. Most respondents performed piecemeal harvesting. Whenever farmers delayed the harvest, they risked severe damage of their sweet potato crops by weevils (Cylas spp., Coleoptera: Curculionidae) and millipedes (Diplopoda). Millipedes pierce and tunnel the storage roots, especially when harvesting is delayed. The farmers did not mention specific natural control agents for millipedes. Knowledge about pests was generally limited, so control strategies were poorly developed, understood and applied

Presentation_1_Gender mainstreaming in sweetpotato breeding and dissemination in Ghana and Malawi.pdf

Gender responsiveness in breeding programs to meet client and end user preferences for crops is essential. This case study analyzes the implementation experience of gender-responsive breeding and variety dissemination in Malawi and Ghana, focusing on good practices and challenges encountered. In Malawi, a training-of-trainers approach was employed to share knowledge among trained farmers. In Ghana, a research study was conducted to identify gender-based preferences for sweetpotato to define breeding objectives. The participation of social scientists, food scientists, and sweetpotato breeders in the GREAT (Gender Researchers Equipped for Agricultural Transformation) team provided a multidisciplinary perspective, addressing questions and responses in the field. Research efforts were strengthened by focusing on food quality through the establishment of an analytical laboratory for rapid evaluation of nutrition and food quality, including sugars. This helped develop sensory analytical capacity to better understand quality attributes and market segments, guiding breeding and improving market opportunities for women. Breeding outcomes resulting from gender inclusion led to the release of some sweetpotato varieties meeting end user and consumer preferences, as well as adoption of OFSP varieties by men and women. Other good practices for gender inclusion and responsiveness include providing funds for gender-based research and activities, engaging gender specialists and social scientists in trans-disciplinary teams, designing program activities with gender considerations, and incorporating traits in seed multiplication and dissemination decisions. Application of these gender inclusion practices resulted in adoption and development of acceptable sweetpotato varieties.</p