College of Agriculture
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The College of Agriculture is committed to advancing agricultural education, research, and community service.
It serves as a center for knowledge creation and dissemination in crop science, animal production,
natural resource management, and sustainable agriculture.
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Item EFFECT OF INTERCROPPING MAIZE VARIETIES WITH DIFFERENT CROPS ON FUNGAL CONTAMINATION OF MAIZE GRAIN IN DOREBAFANA WOREDA SIDAMA REGION(Hawassa University College of Agriculture, 2023) TESHALE TAFESSE LINTAMOMaize (Zea mays) is attacked by many diseases in the field as well as in the storage. Fungi are among the principal causes of deterioration and yield loss on farmers’ maize. The present study was aimed to identify the effect of different crop combinations in the intercropping systems and maize varieties on fungal contamination of maize grain. The experiment was conducted at dorebafana woreda of Sidama region at rukesa suke kebele and the laboratory analysis was conducted at Hawassa University, College of Agriculture, Plant Protection Laboratory. Three maize varieties (Limu, Kurtu and BH 540) and four cropping systems (Maize sole, Maize with haricot bean intercropping, Maize with mung bean intercropping, maize with sweet potato intercropping) were the treatments. The experiment was laid using completely randomized block design (RCBD) with three replications. For each treatment a sample of 100 seeds were tested for fungal contamination using the blotter technique in the laboratory. A total of six fungal genera consisting of nine species of fungi were isolated from maize grains collected from the experimental field. Fusarium sppwere the most frequently isolated ones followed by Aspergillus spp. The fungal contaminations of maize grains were significantly different (p<0.05) between sol cropping and intercropping treatments. The sol cropping had higher fungal contamination level compared to intercropping treatments. On the other hand, i ntercropping maize with haricot bean has resulted in the lowest fungal contamination followed by intercropping maize with mung bean. Fusarium spp had resulted highest contamination level followed by Aspergillus spp, Penicillium spp, Alternaria spp, Trichoderma spp, and Rhizopus sp. Low level of fungal frequency was recorded on limu maize variety. Whereas the variety kurtu had the highest level of fungal contamination. The result of the present study revealed that maize cropping system affects the level of fungal contamination. In the present study it is also seen that maize varieties tested vary in their resistance to fungal contamination. Thus, good agronomic practices like intercropping and variety selection can play determinant role in reduction of fungal contamination in maize grain. Based on the finding of present study, intercropping maize with haricot bean and variety limu can be used to reduce effect of maize contamination with fungi.Item ECOLOGY OF THE AFRICAN MAIZE STALK BORER, Busseola fusca(Fuller) (LEPIDOPTERA: NOCTUIDAE) ON MAIZE (Zea maysL.) IN SOUTHERN ETHIOPIA(Hawassa University College of Agriculture, 2020) ABRHAM TADDELE TEREFEMaize (Zea mays L.) is an important crop in sub-Saharan Africa (SSA) and the developing world. In Ethiopia, smallholderfarmers almost in allregions of the country dominantly produce maize. In sub- Saharan Africa, maize suffers from various biotic and abiotic constraints resulting in considerable yield loss. Among the biotic factors, insect pests particularly fall armyworm and stem borers are currently the most important pests of maize. Stem borers attack maize from seeding up to maturity. The sampling number and unit are important features of any empirical study in which the goal is to make inferences about a population. The number of sampling number and unit could vary with insects being sampled, their distribution patterns purpose of sampling, infestation pattern and economic considerations. Diapausing B. fusca larvae live in maize stem during unfavorable conditions. Environmental factors such as temperature influence the duration of B. fuscalarvae development, intensity and time of pest out break varied between localities. Information on pest incidence, injury and yield loss in the different agro-ecologies will facilitate strategic decisions with regard to selection of management practices. This study provides information on B. fusca, spatial distribution pattern, sampling size, phenology, population density and termination of diapauses larvae, crop injury, and yields losses in maize in southern Ethiopia. xxii During the study periods, B. fusca was present and injurious to maize in all study areas. The spatial distribution pattern of B. fuscawas determined by using four distribution indices namely, Taylor’s power law, Iwao’s mean crowding regression, Lloyd's mean crowding, and index of dispersion. At the mid-whorl stage of maize, the distribution of B. fusca infestation was aggregated and uniform at both silking and maturity stages. At silking as well as mid-whorl stage of maize, B. fuscalarvae exhibited an aggregated distribution pattern but, larvae at maturity stage and pupae in both silking and maturity stages of maize found randomly distributed. To set control options for B. fusca at its economic threshold level in maize farm, required sampling units was determined using four precision levels and Iwao’s patchiness regression. The required sample units to estimate 5 to 30% mean infestation of maize by B. fuscaranged from, 101 - 73, 45 - 32, 25-18 and 16 to 12 in 2015 and 104-76, 42-30, 26-19 and 17 to 12 in 2016, for 10%, 15% , 20% and 25% precision, respectively. For 10% infestation, which is considered as action threshold level for stem borers management on maize, 22 sampling units (660 plants) per hectare at the precision of 20% are required. The phenology of B. fusca was studied at Hawassa and Wolaita Sodo using sowing date and pheromone traps.Three generations of B. fusca per year were observed in southern Ethiopia between May and September. In Hawassa, the first moth flight which emerged from diapause larvae was started at mid-April in 2015 and mid of March, 2016. In Wolaita moth flight started at early May and April in 2015 and 2016, respectively. The potential of crop residues as sources of carry-over populations of the insect was also assessed. Flight period and population density of adult B. fuscafrom diapause state were significantly varied between seasons. Access to water did not enhance pupation during the diapause. Planting of maize at the beginning of April and May xxiii in Hawassa and Wolaita Sodo, respectively could be no longer suitable for oviposition and consumption by second-generation B. larvae. Population density of B. fuscalarvae and pupae were significantly different among years, locations and crop stages. Early and highest infestation of B. fuscaon maize was observed in Gurage followed by Wolaita as compared in Sidama Zone. Higher population density, injury variables and grain yield losses due to B. fuscaon maize were recorded from chemical treated plots as compared with untreated. Tunnel length, hole number, bored internode, larvae and pupae population had a negative effect on grain yield of maize. Increase in altitude positively affected the population density of B. fuscaand the resultant infestation and yield loss. Cultural practice such as crop diversification; disposal of crop residues after maturity can reduce initial establishment of stem borer infestation. Chemical control is one of the components of integrated pest management and should be used only when necessary combined with other management practices. This study provides information on the distribution, biology, pest status and yields losses due to B.fuscaon maize in southern Ethiopia.