Rhizoctonia solani and Pythium spp. are aggressive soil-borne fungal pathogens responsible for seed rot and seedling damping-off of many crops. With increased environmental and public concern over the use of chemicals, biological control of these diseases has been attracting more attention. However, success with this strategy depends on the development of effective antagonists, which requires repeated in vitro and in vivo tests. Bacillus spp. were isolated from a soil sample obtained from a field where sorghum and tef had been grown for at least two years. Potential Bacillus isolates were screened for their ability to inhibit in vitro growth of R. solani and Pythium sp. Among 80 isolates tested, endospore forming Bacillus spp. H44 and H51 gave highest antifungal activity against the two test-pathogens in three consecutive tests. Results demonstrated that both H44 and H51 have potential as biocontrol agents against diseases caused by these two pathogenic fungi. The interaction between three isolates of Trichoderma (T. harzianum Eco-T, Trichoderma spp. SY3 and SY4) and Pythium sp. were investigated using in vitro bioassays together with environmental scanning electron microscopy (ESEM). Visual observation on the dual culture tests revealed that hyphal growth of Pythium was inhibited by these antagonists soon after contact between the two organisms within 3-4 days of incubation. The ESEM investigations showed that all three isolates of Trichoderma grew toward the pathogen, attached firmly, coiled around and penetrated the hyphae of the pathogen, leading to the collapse and disintegration of the host's cell wall. Degradation of the host cell wall was postulated as being due to the production of lytic enzymes. Based on these observations, antibiosis (only by Eco-T) and mycoparasitism (by all three isolates) were the mechanisms of action by which in vitro growth of Pythium sp. was suppressed by these Trichoderma isolates. The reduction of seedling diseases caused by R. solani and a pythium sp. were evaluated by applying the antagonists as seed coating and drenching antagonistic Bacillus spp. (B81, H44 and H51) and Trichoderma (T. harzianum Eco-T and Trichoderma spp. SY3 and SY4). On both crops, R. solani and Pythium sp. affected stand and growth of seedlings severely. With the exceptions of H51, applications all of isoltes to seeds reduced damping-off caused by R. solani in both crops. Application of Eco-T, H44 and SY3 to sorghum controlled R. solani and Pythium sp. effectively by yielding similar results to that of Previcur®. On tef, biological treatments with Eco-T and SY4 reduced seedling damping-off caused by R. solani and Pythium sp., respectively, by providing seedling results similar to the standard fungicides, Benlate® and Previcur®. Most other treatments gave substantial control of the two pathogens on tef. Overall, Bacillus sp. H44 and T harzianum Eco-T were the best biocontrol agents from their respective groups in reducing damping-off by the two pathogens. In all instances, effects of application method on performance of biocontrol agents and adhesive on emergence and growth of seedlings were not significant. A field trial was conducted at Ukulinga Research Farm at the University of Natal, Pietermaritzburg, South Africa, to determine efficacy of biological and chemical treatments on growth promotion and reduction of damping-off incited by R. solani and Pythium sp., and to evaluate the effects of a seed coating material, carboxymethyl cellulose (CMC), on seedling emergence and disease incidence. Seeds of sorghum and tef were treated with suspensions of antagonistic Bacillus H44 or T harzianum Eco-T, or sprayed with fungicides, Benlate® or Previcur®. Application of Benlate® and Previcur® during planting significantly increased the final stand and growth of sorghum seedlings. Seed treatments with both H44 and Eco-T substantially controlled damping-off caused by Pythium, resulting in greater dry weights of seedlings than the standard fungicide. However, they had negative effects when they were tested for their growth stimulation and control of R. solani. The CMC had no significant effect on germination and disease levels. These results showed that these antagonists can be used as biocontrol agents against Pythium sp. However, repeated trials and better understanding of the interactions among the antagonists, the pathogens, the crop and their environment are needed to enhance control efficiency and growth promotion of these antagonists. Some of these biocontrol agents used in this study have the potential to diseases caused by R. solani and Pythium sp. However, a thorough understanding of the host, pathogen, the antagonist and the environment and the interactions among each other is needed for successful disease control using these antagonists. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

Soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi Syd., is a real threat to soybean crops in South Africa. Its ability to spread rapidly and its potential to severely reduce yields have earned it the reputation as the most destructive foliar disease of soybeans. SBR has been reported in South Africa every year since its arrival in 2001. While extensive research had been done on the epidemiology and fungicide application requirements in South Africa, no work into the long term climatic vulnerability of soybean production areas to SBR had been done. This meant soybean producers do not know whether SBR is a threat in their areas. Through this research a SBR algorithm was developed using readily available climate data, viz. temperature and rainfall, to create a daily index specifying the climatic vulnerability of SBR infection. The algorithm was applied to a 50 year historical climate database, and a series of maps was created illustrating the long term vulnerability of different areas to SBR infection. These maps allow soybean producers to understand the climatic vulnerability of their area to SBR infection. Time series graphs were created for selected key soybean production areas to allow soybean producers to distinguish periods of high and low climatic risk during the season. This may help with decisions regarding the planting times, the maturation rate of different cultivars as well as the timing and application of fungicides. The framework for a near real time forecasting system was created outlining how the system could amalgamate recently recorded and forecasted weather data, run it through the SBR algorithm and provide a near real time, as well as forecasted vulnerability, based on the climatic conductivity for SBR infection. Anticipated limitations and difficulties on developing the forecasting system are also outlined. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

The objectives of this study were to establish the effectiveness of chlorpyrifos in suppressing H. armigera population in oranges and to determine the effect chlorpyrifos had on the health of farm pesticide operators. Experiments showed that by applying chlorpyrifos on orange trees, H. armigera larvae population was suppressed significantly. High fruit yields were realized from trees that were sprayed with chlorpyrifos. Visual observation of personnel involved in pesticide related duties, revealed that judicious use of pesticides was not practiced by farm workers in all three farms. Data analysis from questionnaires, health records and interviews proved that farm workers suffered from illnesses that were pesticide related. It was mainly those farm workers in the age group of 31 to 35 years who suffered the most from pesticide related illnesses. / Agriculture and Life Sciences / M. Sc. (Agriculture)

Orientadores: Stanley Robson de Medeiros Oliveira, Carlos Alberto Alves Meira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-20T23:34:35Z (GMT). No. of bitstreams: 1 Megeto_GuilhermeAugustoSilva_M.pdf: 5556599 bytes, checksum: c545e13e7ec81e96cf9e6a3e46d01de2 (MD5) Previous issue date: 2012 / Resumo: A ferrugem asiática, causada pelo fungo Phakopsora pachyrhizi, atualmente é considerada uma das doenças mais importantes e agressivas da soja. A principal forma de controle é a aplicação calendarizada de fungicidas a qual desconsidera o risco de ocorrência da doença. Estudos epidemiológicos buscam compreender os fatores que influenciam na ocorrência e desenvolvimento das epidemias, especialmente aqueles relacionados ao ambiente tais como condições meteorológicas. Com o avanço da tecnologia da informação e do armazenamento de dados, técnicas de mineração de dados (data mining) apresentam-se promissoras para a descoberta de conhecimento em bases de dados epidemiológicos. Este trabalho tem como objetivo avaliar a influência da chuva e da temperatura na ocorrência da ferrugem asiática da soja utilizando árvores de decisão. Para tal, foram obtidos dados de ocorrências da doença em quatro safras, de 2007/2008 a 2010/2011, oriundos do banco de dados do Consórcio Antiferrugem, e dados meteorológicos, provenientes do sistema Agritempo. A análise exploratória dos dados permitiu obter subsídios para compor o conjunto de dados final e definir o escopo deste trabalho, buscando-se características intrínsecas à doença e sua interação com o ambiente, utilizando apenas variáveis de base meteorológica. As variáveis utilizadas foram relacionadas à precipitação e à temperatura, que deram origem a nove atributos avaliados para cada período temporal...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The Asian soybean rust, caused by Phakopsora pachyrhizi, is now considered one of the most important and aggressive diseases of soybean. The main form of control is the scheduled application of fungicides which disregards the the risk of disease occurrence. Epidemiological studies seek to understand the factors that influence the occurrence and development of epidemics, especially those related to the environment such as weather conditions. With the development of information technology and data warehousing, data mining techniques appear to be promising for knowledge discovery in epidemiological databases. This study aims to evaluate the influence of rainfall and temperature on the occurrence of soybean rust by using decision trees models. To accomplish that, data of the occurence of the disease were collected from four seasons, 2007/2008 to 2010/2011, from the Consórcio Antiferrugem and weather data from the Agritempo system. Exploratory data analysis allowed for obtaining subsidies to generate the final data set and define the scope of this work, seeking intrinsic characteristics of the disease and its interaction with the environment, using only meteorological variables. The variables used were related to precipitation and temperature, resulting into nine attributes evaluated in different periods. Such attributes were related to the event of occurrence (Oc) and non occurrence (NaoOc) of the disease (assumed as the thirtieth day prior to the event of occurrence). The results include a predictive model and an interpretive model for classifying events of occurrences and non occurrences of the disease...Note: The complete abstract is available with the full electronic document / Mestrado / Planejamento e Desenvolvimento Rural Sustentável / Mestre em Engenharia Agrícola

Root rot diseases of bean (Phaseolus vulgaris L.) are a problem wherever they are grown, and are a major constraint to dry edible and snap bean production. Root rot is a primary yield limitation of snap bean production in the US, especially within the top three snap bean producing states of Wisconsin, Oregon and New York. Bean root rot pathogens will be present by the end of the first season even when starting with clean ground. The decline in yield can be relatively slow, so growers might not notice or appreciate the hidden yield cost associated with root rot disease. Traditional methods for disease control such as fungicides, crop rotations, cover crops, seedbed preparations have been proven ineffective (either physically ineffective or economically unviable) against root rot. Therefore, genetic resistance is needed. In order to address the need for genetic resistance to root rot in snap beans, the highly root rot resistant line RR6950, a small seeded black indeterminate type IIIA accession of unknown origin, was crossed with OSU5446, a highly root rot susceptible determinate type I blue lake four-sieve breeding line to produce the RR138 recombinant inbred mapping population. In this study we evaluated the RR138 RI population in the F₆ generation for resistance to Fusarium solani root rot in Oregon and Aphanomyces euteiches root rot in Wisconsin. We also evaluated this population for morphological traits and root structural traits including pod height, pod width, pod length, pod wall thickness, strings, seed color, flower color, tap and basal root diameter, and root angle measurements. The RR138 population was also genotyped on the 10K BeanCAP Illumina Beadchip. The Single Nucleotide Polymorphism (SNP) data was used to assemble a high-density linkage map and Quantitative Trait Loci (QTL) for phenotypic data were evaluated. The linkage map produced from this study contained 1,689 SNPs across 1,196cM. The map was populated with 1 SNP for every 1.4cM, spanning across 11 linkage groups. Three QTL associated with A. euteiches root rot resistance were consistently expressed in 2011 and 2012 trials. A. euteiches QTL were found on Pv02, Pv04, and Pv06 and accounted for 7-17% of total genetic variation. Two QTL associated with F. solani were found in 2011 trial on Pv03 and Pv07, account for 9 and 22% of total genetic variation, respectively. We also found several QTL for morphological traits and root structural traits including QTL for pod fiber and pod height on Pv04, pod length on Pv01, strings on Pv01, taproot diameter on Pv05, and shallow basal root angle on Pv05, accounting for 21, 26, 12, 20, 11, and 19% of total genetic variation, respectively. QTL discovered from Oregon data for F. solani resistance did not cluster with QTL for A. euteiches root rot resistance. "SNP0928_7", was highly associated with F. solani resistance on Pv07 and "SNP0508_2", was highly associated with A. euteiches on Pv02. QTL and markers associated with QTL from this study will be of value to snap bean breeders developing root rot resistant lines with processing traits, and provide more information about targeting the mechanism of resistance. / Graduation date: 2013

Soybeans, Glycine max, are an economically and strategically important crop in South Africa (SA). In order to meet local demands, large imports of soybeans are required, e.g., in the 2005/2006 soybean production period, 842 107 tonnes of oilcake were imported. Due to an increase in soybean production throughout the world, diseases that affect this crop have also increased in incidence and severity. Sclerotinia sclerotiorum, the causal organism of sclerotinia stem rot (SSR), is an important yield limiting disease of soybeans, as well as numerous other crops. The pathogen was first reported in SA in 1979. However, it was only in 2002 that this fungus was considered a major pathogen of soybeans in SA. The research reported in this thesis was conducted to investigate the epidemiology of S. sclerotiorum and examine numerous potential control methods for this pathogen, i.e., resistant cultivars, biocontrol, chemical control and seed treatments. A S. sclerotiorum isolate was obtained from sunflowers in Delmas, Mpumulanga, SA, in the form of sclerotia. This isolate was cultured and sent for identification and deposition in the Plant Protection Research Institute collection. This isolate, in the form of mycelia, was used for the duration of the study. For epidemiology studies, the effect of temperature, leaf wetness duration (LWD) and relative humidity (RH) were examined for their effect on rate of pathogen development. Twenty four combinations of temperature (19°C, 22°C, 25°C and 28°C), LWD (24, 48 and 72 hr) and RH (85 and 95%) were investigated. No interaction between temperature, LWD and RH was found. Temperature alone was the only factor that affected disease development. At 22°C, the rate of pathogen development (0.45 per unit per day) was significantly higher than all other temperatures, indicating that this temperature is optimum for disease development. Thirteen different soybean cultivars, i.e., LS6626RR, LS6710RR, LS666RR, LS555RR, LS6514RR, LS678RR, Prima 2000, Pan 626, AG5601RR, AG5409RR, 95B33, 95B53 and 96B01B, commercially grown in SA were investigated for their reaction to S. sclerotiorum. Prima 2000, 96B01B, 95B33 and AG5409RR were considered to be the least susceptible as they showed a significantly low rate of pathogen development (0.28, 0.28, 0.24, 0.23 per unit per day, respectively) and produced a significantly low number of sclerotia (3.03, 3.42, 3.21, 2.38, respectively). LS6626R and LS666RR may be considered most susceptible because of their significantly high rate of pathogen development (0.45 and 0.42 per unit per day, respectively) and high sclerotia production (8.16 and 7.50, respectively). Regression analysis showed a positive correlation coefficient (R2=0.71) between rate of growth of the pathogen and number of sclerotia produced, indicating that a higher rate is associated with a higher number of sclerotia. In vitro dual culture bioassays were performed to identify the biocontrol mechanisms of the biocontrol agents, EcoT® (a seed treatment) and Eco77® (a foliar treatment), against hyphae and sclerotia of S. sclerotiorum. Ultrastructural studies revealed that mycoparasitism is the probable mode of action as initial signs of hyphae of EcoT® and Eco77® coiling around hyphae of S. sclerotiorum were observed. Surface colonization of sclerotia by hyphae of EcoT® and Eco77® was also observed. In vitro antagonism of EcoT® against S. sclerotiorum on soybean seed was performed to determine pre-emergence and post-emergence disease. There was no significant difference in percentage germination between seeds treated with EcoT® and plated with the pathogen, untreated seeds and no S. sclerotiorum, and the control (i.e. no EcoT® and no pathogen). However, percentage non infected seedlings from seeds not treated with EcoT® was significantly lower, suggesting that EcoT® may be successfully used as a seed treatment for the control of SSR. In vivo trials were performed to investigate the effect of silicon (Si) alone, and in combination with Eco77®, on the effect of the rate of disease development. Plants treated with Eco77® had a significantly lower rate of disease development (0.19 per unit per day for plants treated with Eco77® and S. sclerotiorum and 0.20 per unit per day for plants treated with Eco77®, S. sclerotiorum and Si), compared to plants not treated with Eco77® (0.29 per unit per day for plants treated with S. sclerotiorum and 0.30 per unit per day for plants treated with S. sclerotiorum and Si), regardless of the application of Si. Similarly, plants treated with Eco77® had a significantly lower number of sclerotia (0.46 for plants treated with Eco77® and S. sclerotiorum and 0.91 for plants treated with Eco77®, S. sclerotiorum and Si), compared to plants not treated with Eco77® (3.31 for plants treated with S. sclerotiorum and 3.64 for plants treated with S. sclerotiorum and Si). The significantly lower rate of disease development coupled with a significant reduction in sclerotia showed that Eco77®, and not Si, was responsible for reducing the severity of SSR. A strong positive correlation between rate of disease development and the number of sclerotia produced (R2=0.79) was observed. For the investigation of various fungicides for the control of S. sclerotiorum, in vitro trials to determine the potential of three different fungicides at different rates, i.e., BAS 516 04F (133 g a.i. ha-1), BAS 516 04F (266 g a.i. ha-1), BAS 512 06F (380 g a.i. ha-1) and Sumisclex (760 g a.i. ha-1) were initially conducted. The control (non-amended PDA) had a significantly higher area under mycelial growth curve (243.0) than all fungicides tested. BAS 516 04F (at both concentrations) and BAS 512 06F completely inhibited the mycelial growth of S. sclerotiorum. Sumisclex inhibited the fungus by 89.07%. For in vivo trials, preventative treatments, i.e., BAS 516 04F (133 g a.i. ha-1), BAS 516 04F (266 g a.i. ha-1), BAS 512 06F (380 g a.i. ha-1), curative treatment, i.e. Sumisclex (760 g a.i. ha-1) and a combination preventative/curative treatment, i.e., BAS 512 06F (380 g a.i. ha-1)/Sumisclex (570 g a.i. ha-1) were investigated. No significant difference in disease severity index (DSI) was found between fungicide treatments and the inoculated control. BAS 512 06F and BAS 512 06F/Sumisclex had significantly lower grain yields (6.09 g and 5.96 g, respectively) compared to all other treatments. There was a positive correlation coefficient (R2=0.76), between DSI and grain yield, indicating that a high DSI is correlated with low grain yield. Trials to evaluate the effect of commercially available and currently unregistered seed treatments for the control of S. sclerotiorum on soybean seeds in vivo and in vitro were performed. Seed germination tests were performed to determine if seed treatments had any negative effects on seed germination in vitro. All seed treatments tested, i.e., BAS 516 03F (8, 16 and 32 ml a.i. 100 kg-1 seed), BAS 512 00F (7.5, 15 and 32 ml a.i. 100 kg-1 seed), Celest XL (100, 125, 200 and 250 ml a.i. 100 kg-1 seed), Sumisclex (5 and 10 ml a.i. 100 kg-1 seed), Benomyl (150 g a.i. 100 kg-1 seed), Captan (240 ml a.i. 100 kg-1 seed), Thiulin (180 g a.i. 100 kg-1 seed) and Anchor Red (300 ml a.i. 100 kg-1 seed), showed no negative effect on seed germination. For in vivo trials, BAS 516 03F (16 and 32 ml a.i. 100 kg-1 seed), BAS 512 00F (7.5, 15 and 32 ml a.i. 100 kg-1 seed), Celest XL (100, 125, 200 and 250 ml a.i. 100 kg-1 seed), Sumisclex (5 and 10 ml a.i. 100 kg-1 seed), Benomyl and Anchor Red had significantly similar percent germination and percent seedling survival as the untreated/uninoculated control. These seed treatments should be recommended for the control of S. sclerotiorum, as they protected seed during germination and subsequent seedling development. BAS 516 03F (8 ml a.i. 100 kg-1 seed) should not be recommended for the control of SSR, as it gave the lowest percent germination and percent seedling survival. The results presented in this thesis have helped to identify optimal environmental conditions for the development of S. sclerotiorum, which is important for the development of forecasting models for disease control. The least and most susceptible cultivars of those tested have been identified. Biocontrol using Eco77® as a foliar application showed great potential. The effect of Si needs to be further investigated, including the testing of more frequent applications and higher concentrations. The fungicides tested in this research did not show any potential for the control of SSR. However, the spray programme tested is for the control of soybean rust (Phakopsora pachyrhizi), and was investigated for its potential for the control of SSR. The spray programme, fungicide application and rating scale needs to be modified, to determine the true potential of these fungicides for the control of SSR. Numerous seed treatments have shown potential for the control of seed infection by SSR. Due to difficulties in producing ascospores, which are the primary source of inoculum for this pathogen in the field, all studies in this research were conducted with mycelia and not ascospores. The production, collection and storage of ascospores needs to be thoroughly investigated, and research conducted with ascospores. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

In the KwaZulu-Natal (KZN) Midlands North region of South Africa, the importance and increased prevalence of endemic scarabaeids, particularly Hypopholis sommeri Burmeister and Schizonycha affinis Boheman (Coleoptera: Melolonthinae), as soil pests of sugarcane, and a need for their control was established. The development of a mycoinsecticide offers an environmentally friendly alternative to chemical insecticides. The identification of a diversity of white grub species, in two Scarabaeidae subfamilies, representing seven genera were collected in sugarcane as a pest complex. Hypopholis sommeri and S. affinis were the most prevalent species. The increased seasonal abundances, diversity and highly aggregated nature of these scarabaeid species in summer months, suggested that targeting and control strategies for these pests should be considered in this season. Increased rainfall, relative humidity and soil temperatures were linked to the increased occurrence of scarab adults and neonate grubs. Beauveria brongniartii (Saccardo) Petch epizootics were recorded at two sites in the KZN Midlands North on H. sommeri. Seventeen different fluorescently-labelled microsatellite PCR primers were used to target 78 isolates of Beauveria sp. DNA. Microsatellite data resolved two distinct clusters of Beauveria isolates which represented the Beauveria bassiana senso stricto (Balsamo) Vuillemin and B. brongniartii species groups. These groupings were supported by two gene regions, the nuclear ribosomal Internal Transcribed Spacer (ITS) and the nuclear B locus (Bloc) gene of which 23 exemplar Beauveria isolates were represented and sequenced. When microsatellite data were analysed, 26 haplotypes among 58 isolates of B. brongniartii were distinguished. Relatively low levels of genetic diversity were detected in B. brongniartii and isolates were shown to be closely related. There was no genetic differentiation between the two sites, Harden Heights and Canema in the KZN Midlands North. High gene flow from swarming H. sommeri beetles is the proposed mechanism for this lack of genetic differentiation between populations. Microsatellite analyses also showed that B. brongniartii conidia were being cycled from arboreal to subterranean habitats in the environment by H. sommeri beetles. This was the first record of this species of fungus causing epizootics on the larvae and adults of H. sommeri in South Africa. The virulence of 21 isolates of Beauveria brongniartii and two isolates of B. bassiana were evaluated against the adults and larvae of S. affinis and the adults of H. sommeri and Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). Despite being closely-related, B. brongniartii isolates varied significantly in their virulence towards different hosts and highlighted the host specific nature of B. brongniartii towards S. affinis when compared to B. bassiana. Adults of S. affinis were significantly more susceptible to B. brongniartii isolates than the second (L2) or third instar (L3) grubs. The median lethal time (LT₅₀) of the most virulent B. brongniartii isolate (C13) against S. affinis adults was 7.8 days and probit analysis estimated a median lethal concentration (LC₅₀) of 4.4×10⁷ conidia/ml⁻¹. When L2 grubs were treated with a concentration of 1.0×10⁸ conidia/ml⁻¹, B. brongniartii isolates HHWG1, HHB39A and C17 caused mortality in L2 grubs within 18.4-19.8 days (LT₅₀). Beauveria brongniartii isolate HHWG1 was tested against the L3 grubs of S. affinis at four different concentrations. At the lowest concentration (1×10⁶ conidia/ml⁻¹), the LT₅₀ was 25.8 days, and at the highest concentration (1×10⁹ conidia/ml⁻¹) the LT₅₀ dropped to 15.1 days. The persistence of B. bassiana isolate 4222 formulated on rice and wheat bran and buried at eight field sites in the KZN Midlands North was evaluated by plating out a suspension of treated soil onto a selective medium. All eight field sites showed a significant decline in B. bassiana CFUs per gram of soil over time, with few conidia still present in the samples after a year. Greater declines in CFUs were observed at some sites but there were no significant differences observed in the persistence of conidia formulated on rice or wheat bran as carriers. Overall, poor persistence of B. bassiana isolate 4222 was attributed to suboptimum temperatures, rainfall, which rapidly degraded the nutritive carriers, attenuated fungal genotype and the action of antagonistic soil microbes. Growers’ perceptions of white grubs as pests and the feasibility of a mycoinsecticide market were evaluated by means of a semi-structured questionnaire. The study showed that the reduced feasibility of application, general lack of potential demand for a product, high cost factors and most importantly, the lack of pest perception, were factors which would negatively affect the adoption of a granular mycoinsecticide. Growers however exhibited a positive attitude towards mycoinsecticides, and showed all the relevant attributes for successful technology adoption. It is recommended that because B. brongniartii epizootics were recorded on target pests which indicated good host specificity, dispersal ability and persistence of the fungus in the intended environment of application; that a mycoinsecticide based on this fungal species be developed. What will likely increase adoption and success of a mycoinsecticide is collaboration between various industries partners to increases market potential in other crops such as Acacia mearnsii De Wild (Fabales: Fabaceae).

The use of pheromone-based or semiochemical lures and devices for the detection of insect pest population and monitoring in agriculture is a common practice. In many countries the use of these devices is exempt from registration requirements based on regulatory thresholds set by the relevant authorities, however, not in South Africa. The question arises whether the pheromones or semiochemicals dispensed through such devices, influence the naturally occurring compounds observed and whether a concern of toxicity and ecotoxicity is justified. A tomato field was selected in a commercial growing area of South Africa and a novel five-component lure, T.V. PheroLure®, was identified from a local manufacturer, Insect Science (Pty) Ltd. The T.V. PheroLure® consists of a Volatile Organic Compound (VOC) blend which is placed in a polyethylene bulb. Tomato VOCs were collected before, during and after the application of the T.V. PheroLure® which was used in combination with a yellow bucket funnel trap. The VOCs were collected at different heights (0 cm, 30 cm and 60 cm) of the tomato plants, from planting until harvest (22 weeks) and surrounding tomato fields without the T.V. PheroLure®. The results obtained indicated that: (i) the T.V. PheroLure® had no significant influence on the natural VOCs observed in the tomato field and (ii) that the height of sampling had no influence on VOCs observed. This study also indicated that apart from a slight increased contribution of limonene, there was no significant influence observed from the T.V. PheroLure® compounds on the natural background VOCs found in the tomato field. Therefore, it could be argued that the natural phenology of the plant has a greater influence on the VOCs observed than T.V. PheroLure® and that the concern of toxicity and ecotoxicity is unjustified when using these devices for monitoring purposes only. / Environmental Sciences / M. Sc. (Environmental Science)