Thesis (M.A. Agricultural Administration (Pasture Science)) -- University of Limpopo, 2014 / In the summer rainfall areas of South Africa small scale farmers, as well as commercial farmers experience low animal production due to a lack of good quality roughage. The nutritional value of the rangeland cannot maintain livestock during autumn and winter. Producing winter fodder could be expensive and literature showed that planting fodder radish and turnip might be a cheap relative option (not in sweet veld). Winter supplementation contributes largely to high input costs in livestock production, which can make this enterprise uneconomically. For this reason alternative winter feeding strategies should be investigated, like the use of Brassica and Raphanus species for feed supply, of high quality, in winter. Two Localities [Syferkuil, (University of Limpopo’s experimental farm (Limpopo) and Dewageningsdrift, (Hygrotech Experimental farm (Gauteng)] were used for this research project. On the two localities three different factors were tested:  Three planting dates (February, March and April)  Three cultivars (Nooitgedacht fodder radish, Forage star turnip (not on Syferkuil) and Mammoth purple top turnip)  Three cutting frequencies (first cut10 weeks after planting + regrowth; first cut 14 weeks after planting + regrowth and 18 weeks after planting, no regrowth). Samples (for dry matter production and nutritional value analysis) were collected at both localities as per cutting frequency treatments during the 2007 growing season. The samples were used to evaluate the influence of the mentioned treatments on total dry matter production, nutritional value, leaf production and tuber production of the three cultivars. At Syferkuil the DM production Nooitgedacht fodder radish was higher (5.23 to 5.9 t/ha) than that of Mammoth purple top turnip (3.24 t/ha) when planted in February. The same trend was seen during the March planting date (4.7 t/ha and 3.6 t/ha respectively for 18 W treatment). During the April planting date the highest production was higher (5.07 t/ha and 5.13 t/ha respectively) than that of the March iv planting date. The 10 Weeks + Re-growth cutting treatment resulted in general in the lowest production. At Dewageningsdrift (Gauteng) Nooitgedacht fodder radish produced the highest of all three cultivars at the 18 Weeks treatment, with the highest when planted in March (7.67 t/ha), 5.5 t/ha when planted in April and 5.3 t/ha when planted in February. For the rest of the treatments the DM production of Nooitgedacht varied between 2.9 t/ha and 4.6 t/ha. The highest DM production of Forage star turnip was 3.01 t/ha (10 W+R, February planting date), 1.35 t/ha (14 Weeks + Re-growth, March planting date) and 2.34 t/ha (18 Weeks, April planting date). The highest DM production of Forage star turnip was 2.96 t/ha (18 Weeks, February planting date), 2.59 t/ha (14 Weeks + Re-growth, March planting date) and 4.1 t/ha (18 Weeks, April planting date). An estimation of the grazing/feeding potential of the different cultivars, at different planting dates and defoliation/cutting treatments, was calculated by using the leave and tuber production (variable criteria) from each treatment. The period from the initial cut to the last regrowth cut was a second variable criterion that was used. The third criterion (non-variable) was the standard norm that the daily intake of a matured livestock unit (MLU) of 450 kg is 10 kg. According to the results the following example of a combination of treatments can be used to maintain ± 10 MLU/ha for the longest period in the winter in Limpopo: Plant 1.1 ha Nooigedacht radish in February, utilize from ± 27 April to 22 June, Plant 2.4 ha Nooigedacht radish in April, utilize from ± 22 June to 27 August, Plant 0.9 ha Mammoth purple top in April, utilize from ± 20 August to 3 Oct According to the results the following example of a combination of treatments can be used to maintain ± 10 MLU/ha for the longest period in the winter in Gauteng: Plant 2.1 ha Forage star turnip in February, utilize from ± 12 April to 13 June, Plant 1.7 ha Mammoth purple top in February, utilize from ± 7 June to 28 July, Plant 1.5 ha Forage star turnip in April, utilize from ± 18 July to 29 August, Plant 2.1 ha Forage star turnip in April, utilize from ± 17 August to 4 Oct.

Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliography.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Five field experiments were conducted to evaluate the relative attractiveness of potential beneficial insectary plants to aphidophagous hover flies and parasitic Hymenoptera and the effectiveness of interplanting selected flowering plants in a broccoli field to enhance biocontrol of the cabbage aphid and green peach aphid. In 1996 we established a preliminary screening trial to begin development of our sampling methods and evaluations of the attractiveness of selected flowering plants to hover flies and parasitic Hymenoptera. In 1997, we conducted a field experiment at the Oregon State University Vegetable Research Farm near Corvallis, OR to assess the relative attractiveness of 11 selected flowering plants to hover flies and parasitic Hymenoptera. Six of these plants were also evaluated for attractiveness to aphidophagous hover flies in two on-farm trials. The experimental design was a complete randomized block design, with four replications at the OSU site, and three replications at the two on-farm sites. Attractiveness of flowering plants to hover flies was assessed by conducting weekly timed observations of feeding frequencies. Associations of parasitic Hymenoptera were assessed by weekly timed vacuum sampling from a fixed area in plots of flowering plants. Attractiveness differed by dates and sites. Among early-season flowering species, Coriandrum sativa (cilantro) was highly attractive to aphidophagous hover flies and Brassica juncea (mustard), Fagopyrum esculentum (buckwheat) and Agastache rugosa (Korean licorice mint) were most attractive to parasitic Hymenoptera. Among late-season flowers, Achillea millefolium (yarrow), Foeniculum vulgare (fennel) and Agastache rugosa (Korean licorice mint) were most attractive to hover flies, but attractiveness to parasitic Hymenoptera did not differ. An on-farm trial was conducted in 1997 at Stahlbush Island Farm near Corvallis, OR. The objective of this trial was to test the hypothesis that interplanting either alyssum (Lobularia maritima), or cilantro (Coriandrum sativa), with broccoli (Brassica oleracea) would attract aphidophagous hover fly adults and parasitic Hymenoptera, enhance oviposition in the adjacent crop, and increase larval predation and parasitism in the adjacent crop, resulting in suppressed cabbage aphid (Brevicoryne brassicae) and green peach aphid (Myzus persicae) populations in the broccoli crop. The predominate hover fly species present were Toxomerus occidentalis and T. marginatus. More adult female T. occidentalis were caught in pan traps in plots with alyssum than in cilantro or control plots. More hover fly eggs were found on broccoli leaves and a higher percent of the aphids present were parasitized by Hymenoptera in plots with alyssum than in cilantro or control plots. However, no differences in aphid intensities were found between treatment and control plots. A comparison between the mean number of hover fly eggs found per broccoli leaf and the mean number of aphid counted per broccoli leaf suggests there is an association between the two. There appears to be an aphid density threshold below which few hover fly eggs are laid. Gravid females were present in the crop from the first sampling date on, yet hover fly eggs were not found in the crop until the second to last sampling date. Our results indicate that the presence of alyssum enhanced hover fly activity, but did not result in increased larval predation on aphids in the crop. In 1997 a survey of hover flies was conducted at each of the four experimental sites. Hover flies were captured with sweep nets. Representative specimens were identified to species by Christian Kassebeer, University of Kiel, Germany and subsequent identifications were made from reference specimens and with taxonomic keys. Twenty species were identified, 16 of which are aphidophagous. At the OSU site and the two on-farm sites, where the relative attractiveness of flowering plants was assessed, the six most common aphidophagous species, collected at all three sites, were: Meliscaeva cinctella, Toxomerus marginatus, T. occidentalis, Sphaerophoria sulphuripes, S. pyrrhina, and Scaeva pyrastri. / Graduation date: 1998

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Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 119-127). Also available on the World Wide Web.