Commercial sugarcane in South Africa is a monoculture, and therefore lacks vegetation diversity, which is instrumental in increasing associated faunal diversity. Diverse habitats tend to support more stable populations of herbivorous and predacious animals. It is hypothesised that lack of this diversity in sugarcane was partially responsible for the existence of Eldana saccharina infestation levels that are higher than is commercially acceptable. Amongst the available E. saccharina control strategies, is habitat management. This has been developed with the view of increasing and enhancing predator foraging activity. Through increasing arthropod predator abundance and activity, it is believed that E. saccharina control may be enhanced. In this study, habitat diversity was increased through intercropping beans within sugarcane. Arthropod populations were monitored throughout the sugarcane-growing period, to determine what effect this intercropping had on known potential arthropod predator populations of E. saccharina. The study site was divided into two plots: the intercrop (beans planted within sugarcane rows: sugarcane-bean intercrop) and sole sugarcane: control plot. At monthly intervals, epigeal arthropods were sampled with pitfall traps, while foliage associated arthropods were sampled with a suction trap. Predator activity at the base of the sugarcane stalk, where E. saccharina lays its eggs was monitored with sticky traps. Sampling took place in the sugarcane-bean intercrop and control plots as well as in the roadway bordering the study site. Epigeal predator habitat preference was assessed by randomly placing pitfall traps in the sugarcane rows, bean rows, interrows between sugarcane rows, interrows between sugarcane and bean rows and the roadway. Corresponding with monthly trapping, an E. saccharina infestation and damage survey was conducted. Environmental factors such as weather, light intensity, plant (beans and sugarcane) phenology and weed density were measured, and their effect on E. saccharina potential arthropod predators examined. At harvest, sugarcane stalks were sampled for sucrose yield analysis. Potential E. saccharina predators that were captured included species of the orders and/or families Acarina, Blattidae, Formicidae (Pheidole megacephala and Dorylus helvolus) and Araneida (Lycosidae, Oxyopidae, Thomisidae and Salticidae). P. megacephala and species of Acarina were the only predators caught with all three trapping techniques, thus indicating that they occurred both on the ground and foliage. D. helvolus and Acarina were the only predators caught in significantly higher numbers in the intercrop, suggesting that increased habitat management had positively affected their population sizes. D. helvolus were captured both on the ground and length of sugarcane stalk, while species of Acarina were captured on the ground, foliage and at the base of sugarcane stalk, indicating that they forage at the base of the stalk, where E. saccharina activity is concentrated. Specific ground habitats preferred by D. helvolus included the sugarcane rows and bean rows, while Acarina preferred the interrows between sugarcane and bean rows. Despite the generally low E. saccharina infestation levels during this study, significantly higher levels of infestation occurred in the intercrop when compared to sole sugarcane. As expected with high infestation, higher (although not statistically significant) damage occurred in the intercrop. Surprisingly, sucrose yield and sugarcane stalk mass were slightly higher in the intercrop. The implications of the observations made during this study are discussed in the context E. saccharina management. / Thesis (M.Sc.)-University of Durban-Westville, 1998.

Alleycropping is an agroforestry technology of planting crops between rows of trees, preferable legumes to promote an interaction among them with positive benefits in terms of improving soil fertility and hence good crop yields. The technology has been tested with a variety of trees/shrubs species in association with crops (alleycropping) or with grasses (alleygrazing), sometimes with encouraging results and sometimes not, in a wide range of environmental conditions around the world. Research in alleycropping started in late 1970s and sinc~ then many publications have been released. However, little or nothing has been reported about this technology using black wattle and the fever tree, two nitrogen-fixing trees common in South Africa and reported as fast-growing species which produce a considerable amount of biomass within a short period of time. Due to that fact, a two-year trial was established in 2003 at the Ukulinga research farm, Pietermaritzburg, South Africa to evaluate the potential of the two tree species under alleycropping with maize and cowpeas as joint intercrops, under alleycropping with pumpkin, and under alleygrazing with Eragrostis curvula and with Panicum maximum. The trial assessed the crop yields and the biomass production from all the components, and their fodder digestibility using Neutral Detergent Fibre (NDF) and Acid Detergent Fibre (ADF) determinations. Additionally the changes in tree grovlth vaa."'i.ables (difu~eter, total height, total \lollhl1e and biomass) were mortitored to produce regression equations to predict those variables, one from another, using regression analysis. The diameter was taken at ground level (dgl) and at the height of 1.3 m, normally called diameter at breast height (dbh). The results showed that tree growth and biomass production were better in black wattle alleycropping than in association with the fever tree. The average dgl of black wattle after 12 months was 48mm and the average dbh was 36mlll. Over the same period the total tree height was about 406cm. A tree pruning was done to one-year old black wattle in the whole trial and the prunings produced about 5.6t/ha of fresh foliage biomass in the association with maize and cowpea and 4.5t/ha in the association with pumpkin. In alleygrazing the growth variables were similar to those obtained in alleycropping but the biomass production was considerably different. The prunings produced about 7.66t/ha of fresh foliage biomass. The dry matter biomass from the prunings was 1.96t/ha, 1.58t/ha and 2.68t/ha in the association with maize and cowpeas, pumpkin and E. curvula respectively. The dry matter was obtained from 4days- oven-dried samples and it was 35% of the fresh foliage biomass and 60% of the fresh woody biomass. The fever tree did not grow significantly during the study period and due to that fact, the species was discarded from the study. Similarly, because after several endeavours using different seed lots, P. maximum had germinated very unevenly, and this grass was excluded from the experimentation. Values ofNDF and ADF less than 35% are considered good, between 35% and 60% fair and poor if greater than 50%. Using is classification the NDF and ADF values from this study were good in pumpkin (30.5% and 29.9%) and cowpeas (36.5% and 46.9%) biomass, fair in E. curvula (41.9% and 39.9%) and maize stover (53.6% and 42.1%) and poor in black wattle (76.58% and 68.1%) foliage. If black wattle is to be used as fodder, it must be mixed with highly digestible fodder like P. maximum, Digitaria sp., and other legume plants, to increase animal intake and to avoid any risk of it becoming an animal hazard due to tannin effects. The regression equations produced linear relationships between dgl and age, and biomass and dbh. The other interactions were not linear. The best equations were obtained in the interaction between dgl and age (dgl= 4.8*Age -7.03; R2 =0.86; SE= 6.6), dgl and height (h= -0.03dg12 + 10.5dgl - 21.25; R2= 0.96, SE= 42.9, h= height), biomass and dbh (lny = 2.409*lndbh; R2=0.99, SE=O.O, Y= tree foliage biomass). During the study, monkeys, cattle, birds and bushbucks posed a threat to the success of the study due to damage they caused to the crops. It was possible to keep the damage below the critical levels, although at high cost. / Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

Wild mustard (Brassica spp.) is used as an edible wild leafy vegetable by indigenous people in South Africa. The potential of wild leafy vegetables in agriculture is not well understood, because there is generally no agronomic research on their production practices. The objective of this study was to examine the performance of three wild mustard species (herein referred to as I, K and M) over four cropping seasons in an intercropping system with green beans (Phaseolus vulgaris L. cv. Imbali). The crops were grown with and without organic fertiliser under dryland conditions at two sites (The University of KwaZulu-Natal Research Farm, Ukulinga and in a rural area of Umbumbulu, KwaZulu-Natal within the farmers' locality) during autumn, winter, spring and summer of 2004 to 2005. Plant development (leaf number, plant height and fresh biomass) during the first six weeks after sowing and seed yield were used to determine agronomic performance of each species. Nutrient status of the rhizosphere soil was determined at 42 days after sowing for each species to determine what effect growing the species would have on mineral availability. Wild mustard production significantly (P < 0.01) performed better at Ukulinga than Umbumbulu. Polyculture was beneficial for wild mustard leaf accumulation and green bean production as determined by land equivalent ratios greater than one for all species combinations, regardless of fertiliser application. Cool environmental conditions occurring in autumn and spring were more favourable (P < 0.05) for wild mustard and green bean biomass accumulation than summer and winter conditions. However, wild mustard seed yield was highest in winter compared with autumn and spring, and there was no measurable seed production in summer. Soil analysis results at 42 days after sowing showed an increase in P, K, Cu and Mg in the rhizosphere of wild mustard without organic fertiliser. Polyculture improved Zn, Cu, Mn and K in wild mustard leaf tissue. It is concluded that wild mustard can be grown as a leafy vegetable throughout the year, but it requires cool environmental conditions to enhance seed yield. Species M significantly yielded better biomass and seeds than species I and K during all the seasons. However, species K performed the least in all aspects. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.