https://hdl.handle.net/10646/3 2026-04-16T04:38:19Z https://hdl.handle.net/10646/3379 Spatiotemporal patterns of clinical bovine dermatophilosis in Zimbabwe 1995-2014 Ndhlovu, Daud N.; Chikerema, Sylvester M.; Masocha, Mhosisi; Nyagura, Mudavanhu; Pfukenyi, Davies M.; Ndhlovu, Felistas A retrospective study of clinical bovine dermatophilosis outbreaks and cases for the period 1995-2014 was conducted, using data obtained from the Division of Veterinary Services (DVS). A total of 3856 outbreaks and 26 659 cases of dermatophilosis were reported countrywide during this period. The post rainy season accounted for 37.9% of the outbreaks followed by the rainy season (26.7%), cold dry season (22.1%) and the hot dry season (13.2%). A retrospective space-time scan statistic in SaTScan™ was used to detect clusters. From this study, it was evident that dermatophilosis was spreading from the north-west of Zimbabwe through the central to the north-east during the period 2010-2014. Five clusters were identified mainly in the central and north-western regions of Zimbabwe. The primary cluster was centred at Ungwe, Gokwe district in Midlands; the second, third, fourth and fifth likely clusters were centred at Bonga (Mashonaland Central), ARDA (Mashonaland West), Nsenga (Matabeleland North) and Zanda in Gokwe, respectively. The findings of this study suggest the continued spread of dermatophilosis across the country; as such the Department of Livestock and Veterinary Services are advised to develop measures aimed at managing this spread such as dipping, quarantine, movement control and raising farmer awareness. 2017-06-27T00:00:00Z https://hdl.handle.net/10646/2682 Selection of optimum vegetative indices for the assessment of tobacco float seedlings response to fertilizer management Swotwa, Ezekia; Maasdorp, Barbara; Murwira, Amon; Masuka, Anxious The experiment sought to establish the vegetative indices for assessing tobacco float seedling varieties’ response to different fertilizer rates. A factorial design, with 3 variety × 4 fertilizer management treatments, was used. The N : P : K treatments were applied at 7, 21, and 35 days after sowing, while N treatments were applied at 42 days. Radiometric measurements were taken at 49, 56, 64, and 79 days after sowing on 8 tray plots, using a multispectral radiometer. Mature seedling samples were harvested at day 79 and stem lengths were determined before processing for total N analysis. All the five channels of the radiometer, the NDVI, and the SRI had a strong relationship with fertiliser rate. Both the NDVI and SRI for T66 were greater (P < 0.05) than those for KRK26 and KE1. The SRI had a stronger relationship with seedling dry mass, seedling count/tray, and stem length than the NDVI. The NDVI also showed a stronger relationship with total N than the SRI. The minimum threshold SRI and NDVI values and optimum growth (100% fertilser) were 0.72 and 6.1. This information is useful in identifying and estimating tobacco seedbed area and seedling vigour using remote sensing and, therefore, is important in forecasting potential tobacco crop area and yield. 2012-05-21T00:00:00Z https://hdl.handle.net/10646/1412 Remote sensing applications in tobacco yield estimation and the recommended research in Zimbabwe Swotwa, Ezekia; Masuka, Anxious; Maasdorp, Barbara; Murwira, Amon; Shamudzarira, Munyaradzi Tobacco crop area and yield forecasts are important in stabilizing tobacco prices at the auction floors. Tobacco yield estimation in Zimbabwe is currently based on statistical surveys and ground-based field reports.These methods are costly, time consuming, and are prone to large errors. Remote sensing can provide timely information on crop spectral characteristics which can be used to estimate crop yields. Remote sensing application on agriculture in Zimbabwe is still very limited. Research should focus on identifying suitable reflectance indices that are related to tobacco growth and yield. Varietal yield response to fertilizer and planting dates as well as suitable temporal windows for spectral data collection should be identified. The challenges of the different tobacco land sizes have to be overcome by identifying suitable satellite platform, with sufficient spectral resolution to separate the tobacco crop from the adjacent competing crops and non-crop vegetative surfaces.The identified suitable index should be strongly correlated with tobacco in season dry mass and yield. The suitable vegetative indices can be employed in establishing tobacco cropped area and then apply the long-term area yield relationship from government and nongovernmental statistical departments to estimate yield from remote sensing derived cropped area. 2013-10-01T00:00:00Z https://hdl.handle.net/10646/1411 Spectral indices: In-season dry mass and yield relationship of flue-cured tobacco under different planting dates and fertiliser levels Svotwa, Ezekia; Masuka, Anxious; Maasdorp, Barbara; Murwira, Amon This experiment investigated the relationship between tobacco canopy spectral characteristics and tobacco biomass. A completely randomized design, with plantings on the 15th of September, October, November, and December, each with 9 variety × fertiliser management treatments, was used. Starting from6 weeks after planting, reflectance measurements were taken fromone row, using a multispectral radiometer. Individual plants from the other 3 rows were also measured, and the above ground whole plants were harvested and dried for reflectance/dry mass regression analysis. The central row was harvested, cured, and weighed. Both the maximum NDVI and mass at untying declined with later planting and so was the mass-NDVI coefficient of determination. The best fitting curves for the yield-NDVI correlations were quadratic. September reflectance values from the October crop reflectance were statistically similar (𝑃 > 0.05), while those for the November and the December crops were significantly different (𝑃 < 0.05) fromthe former two.Mass at untying andNDVI showed a quadratic relationship in all the three tested varieties.Theoptimum stage for collecting spectral data for tobacco yield estimation was the 8–12 weeks after planting.The results could be useful in accurate monitoring of crop development patterns for yield forecasting purposes. 2013-08-13T00:00:00Z