Emmanuel Yamoah - Academia.edu (original) (raw)

Papers by Emmanuel Yamoah

New Zealand Journal of Forestry Science, 2016

Background: A large population of Paropsisterna beata (eucalyptus leaf beetle) was detected on Eu... more Background: A large population of Paropsisterna beata (eucalyptus leaf beetle) was detected on Eucalyptus nitens (H. Deane & Maiden) Maiden (Myrtaceae) at Whitemans Valley, a suburb east of Upper Hutt, Wellington, in 2012. The suburb is a semi-rural residential area with a large number of eucalypt, planted for amenity, shelterbelt and firewood. Surveillance to delimit spread showed that the beetle population was confined to about 0.7 ha consisting of about 40 eucalypts. The Ministry for Primary Industries (MPI) initiated a response to eradicate the beetle population. Findings: Aerial applications of Dominex EC 100 (alpha-cypermethrin) and ground applications of Talstar (bifenthrin) respectively over a 15-month period targeted the adults and larvae in the foliage and the pre-pupae, larvae and emerging adults in the leaf litter. Removal of overwintering habitat by stripping loose bark from host trees further reduced the beetle population. Following these treatments, the beetle has not been detected through a series of surveys using light traps, bark inspection, sticky tapes, visual inspection from the ground, climbing and felling host trees for inspection for 2 years since the last detection of two adults on neighbouring trees. Conclusions: The P. beata population has been successfully eradicated using a combination of aerial and groundbased application of insecticides. The use of precision aerial applications (spot-spraying) has provided an additional tool for incursion response.

Kuwait Chapter of Arabian Journal of Business and Management Review, 2013

In this study, the primary objective was to investigate the factors that affect the performance o... more In this study, the primary objective was to investigate the factors that affect the performance ofsales personnel of insurance companies, with specific focus on factors such as motivation and resourcefulness of the sales person. Using descriptive survey methodology, data was collected from sales personnel of ten insurance companies in Ghana. Findings suggest that motivation is a key factor influencing the performance of insurance sales personnel.

New Zealand Entomologist, 2011

The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse se... more The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse seed weevil Apion ulicis Förster, (Coleoptera: Apionidae), gorse pod moth Cydia ulicetana Denis and Schiffermüller (Lepidoptera: Tortricidae) and gorse thrips Sericothrips staphylinus Haliday (Thysanoptera: Thripidae) were assessed for their ability to carry and deposit the conidia of a plant pathogenic fungus Fusarium tumidum Sherb. on agar plates in

Australian Journal of Entomology, 2008

Microbial population and diversity on the exoskeletons of four insect species associated with gor... more Microbial population and diversity on the exoskeletons of four insect species associated with gorse (Ulex europaeus L.) Emmanuel Yamoah,1* E Eirian Jones,1 Richard J Weld,1† David M Suckling,2 Nick Waipara,3 Graeme W Bourdôt,4 Alvin KW Hee1 and Alison Stewart1 ...

of a thesis submitted in fulfilment of the requirements for the degree of MAgrSc THE POTENTIAL OF... more of a thesis submitted in fulfilment of the requirements for the degree of MAgrSc THE POTENTIAL OF TAGASASTE (Chamaecytisus palmensis) IN MAINTAINING FERTILITY IN A SUSTAINABLE CROPPING SYSTEM iii The effects of incorporating tagasaste (Chamaecytisus palmensis) dry matter (DM) on the growth and yield of maize (Zea mays L.) was studied in two field experiments in Canterbury, New Zealand. In the first experiment (1997-98), tagasaste DM was incorporated at four rates (0, 5, 10 and 15 t DMlha) and maize was sown four (7 November) and eight (5 December) weeks after tagasaste incorporation. In the second experiment (1998-99), 0 and 10 t DM/ha of tagasaste and 200 kg N/ha were soil incorporated and maize was sown four weeks after tagasaste incorporation (2 November) with no, or with full irrigation. In 1997-98, the incorporation of 15 t DM/ha of tagasaste increased maize DM yield from 19,700 to 25,400 kglha and grain yield by 33 %. This was equivalent to maize production from the plots which received 200 kg N/ha. The November sown crop produced 42 % higher grain yield than the December sown crop. However, the DM yield did not differ with sowing date. Incorporating 15 t DM/ha increased both the weighted mean average growth rate and maximum crop growth rate by 26 % but had no effect on the duration of exponential growth. Leaf area duration increased at 15 t DM/ha of tagasaste but sowing date had no effect. Maize sown in November intercepted about 17 % more photosynthetically active radiation (PAR) but had a lower radiation use efficiency (RUE), than the December sown crop. Tagasaste incorporation at 15 t DM/ha increased RUE by 24 % from 2.59 to 3.22 gDMlMJPAR. Incorporating at least 10 t DM/ha of tagasaste reduced soil bulk density and increased total soil nitrogen but had no influence on the soil C:N ratio or pH in both seasons. In 1998-99, application of 200 kg N/ha reduced the soil pH. Volumetric soil water content at grain filling for the unirrigated plots was approximately 66 % of the irrigated plots. iv Dry matter yield increased by 5,200 kg/ha with irrigation in 1998-99. Irrigation did not increase grain yield but, it did increase mean grain weight by 21 %. Irrigation increased DM yield by increasing intercepted PAR from 730 to 860 MJ/m 2. There was a positive and linear relationship between DM accumulation and intercepted PAR and between DM and grain yield. There was a significant interaction between incorporation of tagasaste or 200 kg N/ha and irrigation for DM production. In irrigated plots, the DM yield from the 200 kg N/ha plots at 27,000 kg/ha was about 14 % higher than the yield from plots where tagasaste had been incorporated. These plots produced 3,200 kg more DMiha than the control plots. However, in the unirrigated plots, DM yields were similar in the 10 t DMiha and 200 kg N/ha plots. Both treatments gave higher DM yield than the control. Incorporation of either 10 t DMiha or 200 kg N/ha increased the DM and grain yield by increasing RUE. The results show that tagasaste incorporation can improve soil fertility and increase maize yield provided sowing date coincides with periods of adequate soil moisture.

The overall objective of this study was to test the hypothesis that insects can vector F. tumidum... more The overall objective of this study was to test the hypothesis that insects can vector F. tumidum conidia to infect gorse plants with the aim of developing an alternative approach to mycoherbicide delivery to control weeds. Four potential insect species (Apion ulicis, Cydia ulicetana, Epiphyas postvittana and Sericothrips staphylinus) were assessed for their ability to vector F. tumidum conidia. To achieve this, the external microflora (bacteria and fungi) and the size and location of fungal spores on the cuticle of these insect species were determined. In addition, the ability of the insects to pick up and deposit F. tumidum conidia on agar was studied. Based on the results from these experiments, E. postvittana was selected for more detailed experiments to determine transmission of F. tumidum to infect potted gorse plants. The factors promoting pathogenicity of F. tumidum against gorse and the pathogen loading required to infect and kill the weed were also determined. The external...

ABSTRACT Gorse ( Ulex europaeus L.) is a serious weed in New Zealand. Wounding of gorse plants wa... more ABSTRACT Gorse ( Ulex europaeus L.) is a serious weed in New Zealand. Wounding of gorse plants was assessed to determine if it enhances infection by Fusarium tumidum Sherb. This is an integral part of a long-term objective, using insects as deliberate vectors to disseminate spores of this pathogen to control gorse. Feeding and oviposition activities of these insects on the weed may provide wound sites for fungal entry, which could enhance infection. Plants used in this experiment were 1, 2, 4 and 8 months old. A fixed number of wounds per unit plant size were made in their stems, spines and leaves using needles. The plants were sprayed with a suspension of 106 F. tumidum conidia/mL immediately after wounding. The mean dry weights of wounded plants, which were not sprayed with the pathogen and that of the untreated control, were similar across all age groups at 5.6+or-0.70 (SEM) g/plant. Wounding enhanced F. tumidum infection of all the gorse plants irrespective of their age at treatment. Wounded plants (1-4 months old) which were treated with the pathogen were shorter and had lower dry matter weight than the untreated control ( P <0.001). Plant mortality by F. tumidum infection was higher in the 1 and 2-month old wounded plants compared with non-wounded plants. Wounding increased tip dieback infection in the 4 and 8-month old plants but not in the younger plants of which both wounded and non-wounded plants had 100% tip dieback. It is clear that wounding of older tissue will be required to facilitate F. tumidum infection of mature gorse plants.

of a thesis submitted in fulfilment of the requirements for the degree of MAgrSc THE POTENTIAL OF... more of a thesis submitted in fulfilment of the requirements for the degree of MAgrSc THE POTENTIAL OF TAGASASTE (Chamaecytisus palmensis) IN MAINTAINING FERTILITY IN A SUSTAINABLE CROPPING SYSTEM iii The effects of incorporating tagasaste (Chamaecytisus palmensis) dry matter (DM) on the growth and yield of maize (Zea mays L.) was studied in two field experiments in Canterbury, New Zealand. In the first experiment (1997-98), tagasaste DM was incorporated at four rates (0, 5, 10 and 15 t DMlha) and maize was sown four (7 November) and eight (5 December) weeks after tagasaste incorporation. In the second experiment (1998-99), 0 and 10 t DM/ha of tagasaste and 200 kg N/ha were soil incorporated and maize was sown four weeks after tagasaste incorporation (2 November) with no, or with full irrigation. In 1997-98, the incorporation of 15 t DM/ha of tagasaste increased maize DM yield from 19,700 to 25,400 kglha and grain yield by 33 %. This was equivalent to maize production from the plots which received 200 kg N/ha. The November sown crop produced 42 % higher grain yield than the December sown crop. However, the DM yield did not differ with sowing date. Incorporating 15 t DM/ha increased both the weighted mean average growth rate and maximum crop growth rate by 26 % but had no effect on the duration of exponential growth. Leaf area duration increased at 15 t DM/ha of tagasaste but sowing date had no effect. Maize sown in November intercepted about 17 % more photosynthetically active radiation (PAR) but had a lower radiation use efficiency (RUE), than the December sown crop. Tagasaste incorporation at 15 t DM/ha increased RUE by 24 % from 2.59 to 3.22 gDMlMJPAR. Incorporating at least 10 t DM/ha of tagasaste reduced soil bulk density and increased total soil nitrogen but had no influence on the soil C:N ratio or pH in both seasons. In 1998-99, application of 200 kg N/ha reduced the soil pH. Volumetric soil water content at grain filling for the unirrigated plots was approximately 66 % of the irrigated plots. iv Dry matter yield increased by 5,200 kg/ha with irrigation in 1998-99. Irrigation did not increase grain yield but, it did increase mean grain weight by 21 %. Irrigation increased DM yield by increasing intercepted PAR from 730 to 860 MJ/m 2. There was a positive and linear relationship between DM accumulation and intercepted PAR and between DM and grain yield. There was a significant interaction between incorporation of tagasaste or 200 kg N/ha and irrigation for DM production. In irrigated plots, the DM yield from the 200 kg N/ha plots at 27,000 kg/ha was about 14 % higher than the yield from plots where tagasaste had been incorporated. These plots produced 3,200 kg more DMiha than the control plots. However, in the unirrigated plots, DM yields were similar in the 10 t DMiha and 200 kg N/ha plots. Both treatments gave higher DM yield than the control. Incorporation of either 10 t DMiha or 200 kg N/ha increased the DM and grain yield by increasing RUE. The results show that tagasaste incorporation can improve soil fertility and increase maize yield provided sowing date coincides with periods of adequate soil moisture.

Biocontrol Science and Technology, 2008

Fusarium tumidum is a potential mycoherbicide for gorse control. Phytophagous insects naturally f... more Fusarium tumidum is a potential mycoherbicide for gorse control. Phytophagous insects naturally found on this weed, may serve as deliberate vectors of F. tumidum spores for gorse biocontrol. In this study, the diversity of fungi on the surfaces of three phytophagous insect species of gorse was studied by culturing and culture independent techniques.

Biocontrol Science and Technology, 2008

Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to ... more Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to develop a novel strategy for delivering this potential mycoherbicide using insects as vectors of inoculum. Fusarium tumidum sprayed as a suspension of 1×10 conidia mL on at least 50% of a gorse plant reduced shoot dry weight by 45% (P<0.05). A minimum of 910 viable conidia were

Australian Journal of Entomology, 2008

Fungi and bacteria on the external surfaces of four gorse-associated insect species: gorse seed w... more Fungi and bacteria on the external surfaces of four gorse-associated insect species: gorse seed weevil Apion ulicis Förster (Coleoptera: Apionidae), light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse pod moth Cydia ulicetana Denis and Schiffermüller (Lepidoptera: Tortricidae) and gorse thrips Sericothrips staphylinus Haliday (Thysanoptera: Thripidae), were recovered by washing and plating techniques. The isolates were identified by morphology and polymerase chain reaction (PCR) restriction fragment length polymorphism and sequencing of internally transcribed spacer (ITS) and 16S rDNA. A culture-independent technique (direct PCR) was also used to assess fungal diversity by direct amplification of ITS sequences from the washings of the insects. All insect species carried Alternaria, Cladosporium, Corallomycetella, Penicillium, Phoma, Pseudozyma spp. and entomopathogens. Ninety-four per cent of the 178 cloned amplicons had ITS sequence similarity to Nectria mauritiicola (syn. Corallomycetella repens). E. postvittana carried the largest fungal spores (spore mean surface area of 126 mm 2 ) and the most fungal colony forming units per insect. Methylobacterium aquaticum and Pseudomonas lutea were isolated from all four insect species. P. fluorescens was the most abundant bacterium on the lepidopteran insects. This study presents the diversity of microbial taxa on insect exoskeletons, and provides the basis for developing a novel mycoherbicide delivery strategy for biological control of gorse using insects as vectors of a plant pathogen.

New Zealand Entomologist, 2011

The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse se... more The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse seed weevil Apion ulicis Förster, (Coleoptera: Apionidae), gorse pod moth Cydia ulicetana Denis and Schiffermüller (Lepidoptera: Tortricidae) and gorse thrips Sericothrips staphylinus Haliday (Thysanoptera: Thripidae) were assessed for their ability to carry and deposit the conidia of a plant pathogenic fungus Fusarium tumidum Sherb. on agar plates in laboratory experiments. Epiphyas postvittana, the largest insect species studied, carried and deposited the highest number of F. tumidum conidia. The number of colony forming units recovered from all insect species after exposing them to F. tumidum sporulating cultures for 24 h, declined with time. In subsequent transmission experiments using only E. postvittana, each insect was loaded with 5,000 conidia of F. tumidum and caged together with potted healthy gorse (ulex europaeus L.) at eight insects per plant. The insects deposited 310 conidia per plant on average but neither infection nor plant growth effects resulted. Only directly inoculated plants became infected and were significantly shorter with 42% reduction in fresh shoot weight compared with the control treatment. Epiphyas postvittana on its own did not cause any significant plant damage and did not enhance F. tumidum infection. The insect did not spread the conidia from diseased to healthy plants. The results showed that insects are unlikely to be effective vectors in a 'lure-load-infect' approach for biological control of gorse using F. tumidum.

New Zealand Journal of Forestry Science, 2016

Background: A large population of Paropsisterna beata (eucalyptus leaf beetle) was detected on Eu... more Background: A large population of Paropsisterna beata (eucalyptus leaf beetle) was detected on Eucalyptus nitens (H. Deane & Maiden) Maiden (Myrtaceae) at Whitemans Valley, a suburb east of Upper Hutt, Wellington, in 2012. The suburb is a semi-rural residential area with a large number of eucalypt, planted for amenity, shelterbelt and firewood. Surveillance to delimit spread showed that the beetle population was confined to about 0.7 ha consisting of about 40 eucalypts. The Ministry for Primary Industries (MPI) initiated a response to eradicate the beetle population. Findings: Aerial applications of Dominex EC 100 (alpha-cypermethrin) and ground applications of Talstar (bifenthrin) respectively over a 15-month period targeted the adults and larvae in the foliage and the pre-pupae, larvae and emerging adults in the leaf litter. Removal of overwintering habitat by stripping loose bark from host trees further reduced the beetle population. Following these treatments, the beetle has not been detected through a series of surveys using light traps, bark inspection, sticky tapes, visual inspection from the ground, climbing and felling host trees for inspection for 2 years since the last detection of two adults on neighbouring trees. Conclusions: The P. beata population has been successfully eradicated using a combination of aerial and groundbased application of insecticides. The use of precision aerial applications (spot-spraying) has provided an additional tool for incursion response.

Kuwait Chapter of Arabian Journal of Business and Management Review, 2013

In this study, the primary objective was to investigate the factors that affect the performance o... more In this study, the primary objective was to investigate the factors that affect the performance ofsales personnel of insurance companies, with specific focus on factors such as motivation and resourcefulness of the sales person. Using descriptive survey methodology, data was collected from sales personnel of ten insurance companies in Ghana. Findings suggest that motivation is a key factor influencing the performance of insurance sales personnel.

New Zealand Entomologist, 2011

The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse se... more The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse seed weevil Apion ulicis Förster, (Coleoptera: Apionidae), gorse pod moth Cydia ulicetana Denis and Schiffermüller (Lepidoptera: Tortricidae) and gorse thrips Sericothrips staphylinus Haliday (Thysanoptera: Thripidae) were assessed for their ability to carry and deposit the conidia of a plant pathogenic fungus Fusarium tumidum Sherb. on agar plates in

Australian Journal of Entomology, 2008

Microbial population and diversity on the exoskeletons of four insect species associated with gor... more Microbial population and diversity on the exoskeletons of four insect species associated with gorse (Ulex europaeus L.) Emmanuel Yamoah,1* E Eirian Jones,1 Richard J Weld,1† David M Suckling,2 Nick Waipara,3 Graeme W Bourdôt,4 Alvin KW Hee1 and Alison Stewart1 ...

of a thesis submitted in fulfilment of the requirements for the degree of MAgrSc THE POTENTIAL OF... more of a thesis submitted in fulfilment of the requirements for the degree of MAgrSc THE POTENTIAL OF TAGASASTE (Chamaecytisus palmensis) IN MAINTAINING FERTILITY IN A SUSTAINABLE CROPPING SYSTEM iii The effects of incorporating tagasaste (Chamaecytisus palmensis) dry matter (DM) on the growth and yield of maize (Zea mays L.) was studied in two field experiments in Canterbury, New Zealand. In the first experiment (1997-98), tagasaste DM was incorporated at four rates (0, 5, 10 and 15 t DMlha) and maize was sown four (7 November) and eight (5 December) weeks after tagasaste incorporation. In the second experiment (1998-99), 0 and 10 t DM/ha of tagasaste and 200 kg N/ha were soil incorporated and maize was sown four weeks after tagasaste incorporation (2 November) with no, or with full irrigation. In 1997-98, the incorporation of 15 t DM/ha of tagasaste increased maize DM yield from 19,700 to 25,400 kglha and grain yield by 33 %. This was equivalent to maize production from the plots which received 200 kg N/ha. The November sown crop produced 42 % higher grain yield than the December sown crop. However, the DM yield did not differ with sowing date. Incorporating 15 t DM/ha increased both the weighted mean average growth rate and maximum crop growth rate by 26 % but had no effect on the duration of exponential growth. Leaf area duration increased at 15 t DM/ha of tagasaste but sowing date had no effect. Maize sown in November intercepted about 17 % more photosynthetically active radiation (PAR) but had a lower radiation use efficiency (RUE), than the December sown crop. Tagasaste incorporation at 15 t DM/ha increased RUE by 24 % from 2.59 to 3.22 gDMlMJPAR. Incorporating at least 10 t DM/ha of tagasaste reduced soil bulk density and increased total soil nitrogen but had no influence on the soil C:N ratio or pH in both seasons. In 1998-99, application of 200 kg N/ha reduced the soil pH. Volumetric soil water content at grain filling for the unirrigated plots was approximately 66 % of the irrigated plots. iv Dry matter yield increased by 5,200 kg/ha with irrigation in 1998-99. Irrigation did not increase grain yield but, it did increase mean grain weight by 21 %. Irrigation increased DM yield by increasing intercepted PAR from 730 to 860 MJ/m 2. There was a positive and linear relationship between DM accumulation and intercepted PAR and between DM and grain yield. There was a significant interaction between incorporation of tagasaste or 200 kg N/ha and irrigation for DM production. In irrigated plots, the DM yield from the 200 kg N/ha plots at 27,000 kg/ha was about 14 % higher than the yield from plots where tagasaste had been incorporated. These plots produced 3,200 kg more DMiha than the control plots. However, in the unirrigated plots, DM yields were similar in the 10 t DMiha and 200 kg N/ha plots. Both treatments gave higher DM yield than the control. Incorporation of either 10 t DMiha or 200 kg N/ha increased the DM and grain yield by increasing RUE. The results show that tagasaste incorporation can improve soil fertility and increase maize yield provided sowing date coincides with periods of adequate soil moisture.

The overall objective of this study was to test the hypothesis that insects can vector F. tumidum... more The overall objective of this study was to test the hypothesis that insects can vector F. tumidum conidia to infect gorse plants with the aim of developing an alternative approach to mycoherbicide delivery to control weeds. Four potential insect species (Apion ulicis, Cydia ulicetana, Epiphyas postvittana and Sericothrips staphylinus) were assessed for their ability to vector F. tumidum conidia. To achieve this, the external microflora (bacteria and fungi) and the size and location of fungal spores on the cuticle of these insect species were determined. In addition, the ability of the insects to pick up and deposit F. tumidum conidia on agar was studied. Based on the results from these experiments, E. postvittana was selected for more detailed experiments to determine transmission of F. tumidum to infect potted gorse plants. The factors promoting pathogenicity of F. tumidum against gorse and the pathogen loading required to infect and kill the weed were also determined. The external...

ABSTRACT Gorse ( Ulex europaeus L.) is a serious weed in New Zealand. Wounding of gorse plants wa... more ABSTRACT Gorse ( Ulex europaeus L.) is a serious weed in New Zealand. Wounding of gorse plants was assessed to determine if it enhances infection by Fusarium tumidum Sherb. This is an integral part of a long-term objective, using insects as deliberate vectors to disseminate spores of this pathogen to control gorse. Feeding and oviposition activities of these insects on the weed may provide wound sites for fungal entry, which could enhance infection. Plants used in this experiment were 1, 2, 4 and 8 months old. A fixed number of wounds per unit plant size were made in their stems, spines and leaves using needles. The plants were sprayed with a suspension of 106 F. tumidum conidia/mL immediately after wounding. The mean dry weights of wounded plants, which were not sprayed with the pathogen and that of the untreated control, were similar across all age groups at 5.6+or-0.70 (SEM) g/plant. Wounding enhanced F. tumidum infection of all the gorse plants irrespective of their age at treatment. Wounded plants (1-4 months old) which were treated with the pathogen were shorter and had lower dry matter weight than the untreated control ( P <0.001). Plant mortality by F. tumidum infection was higher in the 1 and 2-month old wounded plants compared with non-wounded plants. Wounding increased tip dieback infection in the 4 and 8-month old plants but not in the younger plants of which both wounded and non-wounded plants had 100% tip dieback. It is clear that wounding of older tissue will be required to facilitate F. tumidum infection of mature gorse plants.

of a thesis submitted in fulfilment of the requirements for the degree of MAgrSc THE POTENTIAL OF... more of a thesis submitted in fulfilment of the requirements for the degree of MAgrSc THE POTENTIAL OF TAGASASTE (Chamaecytisus palmensis) IN MAINTAINING FERTILITY IN A SUSTAINABLE CROPPING SYSTEM iii The effects of incorporating tagasaste (Chamaecytisus palmensis) dry matter (DM) on the growth and yield of maize (Zea mays L.) was studied in two field experiments in Canterbury, New Zealand. In the first experiment (1997-98), tagasaste DM was incorporated at four rates (0, 5, 10 and 15 t DMlha) and maize was sown four (7 November) and eight (5 December) weeks after tagasaste incorporation. In the second experiment (1998-99), 0 and 10 t DM/ha of tagasaste and 200 kg N/ha were soil incorporated and maize was sown four weeks after tagasaste incorporation (2 November) with no, or with full irrigation. In 1997-98, the incorporation of 15 t DM/ha of tagasaste increased maize DM yield from 19,700 to 25,400 kglha and grain yield by 33 %. This was equivalent to maize production from the plots which received 200 kg N/ha. The November sown crop produced 42 % higher grain yield than the December sown crop. However, the DM yield did not differ with sowing date. Incorporating 15 t DM/ha increased both the weighted mean average growth rate and maximum crop growth rate by 26 % but had no effect on the duration of exponential growth. Leaf area duration increased at 15 t DM/ha of tagasaste but sowing date had no effect. Maize sown in November intercepted about 17 % more photosynthetically active radiation (PAR) but had a lower radiation use efficiency (RUE), than the December sown crop. Tagasaste incorporation at 15 t DM/ha increased RUE by 24 % from 2.59 to 3.22 gDMlMJPAR. Incorporating at least 10 t DM/ha of tagasaste reduced soil bulk density and increased total soil nitrogen but had no influence on the soil C:N ratio or pH in both seasons. In 1998-99, application of 200 kg N/ha reduced the soil pH. Volumetric soil water content at grain filling for the unirrigated plots was approximately 66 % of the irrigated plots. iv Dry matter yield increased by 5,200 kg/ha with irrigation in 1998-99. Irrigation did not increase grain yield but, it did increase mean grain weight by 21 %. Irrigation increased DM yield by increasing intercepted PAR from 730 to 860 MJ/m 2. There was a positive and linear relationship between DM accumulation and intercepted PAR and between DM and grain yield. There was a significant interaction between incorporation of tagasaste or 200 kg N/ha and irrigation for DM production. In irrigated plots, the DM yield from the 200 kg N/ha plots at 27,000 kg/ha was about 14 % higher than the yield from plots where tagasaste had been incorporated. These plots produced 3,200 kg more DMiha than the control plots. However, in the unirrigated plots, DM yields were similar in the 10 t DMiha and 200 kg N/ha plots. Both treatments gave higher DM yield than the control. Incorporation of either 10 t DMiha or 200 kg N/ha increased the DM and grain yield by increasing RUE. The results show that tagasaste incorporation can improve soil fertility and increase maize yield provided sowing date coincides with periods of adequate soil moisture.

Biocontrol Science and Technology, 2008

Fusarium tumidum is a potential mycoherbicide for gorse control. Phytophagous insects naturally f... more Fusarium tumidum is a potential mycoherbicide for gorse control. Phytophagous insects naturally found on this weed, may serve as deliberate vectors of F. tumidum spores for gorse biocontrol. In this study, the diversity of fungi on the surfaces of three phytophagous insect species of gorse was studied by culturing and culture independent techniques.

Biocontrol Science and Technology, 2008

Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to ... more Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to develop a novel strategy for delivering this potential mycoherbicide using insects as vectors of inoculum. Fusarium tumidum sprayed as a suspension of 1×10 conidia mL on at least 50% of a gorse plant reduced shoot dry weight by 45% (P<0.05). A minimum of 910 viable conidia were

Australian Journal of Entomology, 2008

Fungi and bacteria on the external surfaces of four gorse-associated insect species: gorse seed w... more Fungi and bacteria on the external surfaces of four gorse-associated insect species: gorse seed weevil Apion ulicis Förster (Coleoptera: Apionidae), light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse pod moth Cydia ulicetana Denis and Schiffermüller (Lepidoptera: Tortricidae) and gorse thrips Sericothrips staphylinus Haliday (Thysanoptera: Thripidae), were recovered by washing and plating techniques. The isolates were identified by morphology and polymerase chain reaction (PCR) restriction fragment length polymorphism and sequencing of internally transcribed spacer (ITS) and 16S rDNA. A culture-independent technique (direct PCR) was also used to assess fungal diversity by direct amplification of ITS sequences from the washings of the insects. All insect species carried Alternaria, Cladosporium, Corallomycetella, Penicillium, Phoma, Pseudozyma spp. and entomopathogens. Ninety-four per cent of the 178 cloned amplicons had ITS sequence similarity to Nectria mauritiicola (syn. Corallomycetella repens). E. postvittana carried the largest fungal spores (spore mean surface area of 126 mm 2 ) and the most fungal colony forming units per insect. Methylobacterium aquaticum and Pseudomonas lutea were isolated from all four insect species. P. fluorescens was the most abundant bacterium on the lepidopteran insects. This study presents the diversity of microbial taxa on insect exoskeletons, and provides the basis for developing a novel mycoherbicide delivery strategy for biological control of gorse using insects as vectors of a plant pathogen.

New Zealand Entomologist, 2011

The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse se... more The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse seed weevil Apion ulicis Förster, (Coleoptera: Apionidae), gorse pod moth Cydia ulicetana Denis and Schiffermüller (Lepidoptera: Tortricidae) and gorse thrips Sericothrips staphylinus Haliday (Thysanoptera: Thripidae) were assessed for their ability to carry and deposit the conidia of a plant pathogenic fungus Fusarium tumidum Sherb. on agar plates in laboratory experiments. Epiphyas postvittana, the largest insect species studied, carried and deposited the highest number of F. tumidum conidia. The number of colony forming units recovered from all insect species after exposing them to F. tumidum sporulating cultures for 24 h, declined with time. In subsequent transmission experiments using only E. postvittana, each insect was loaded with 5,000 conidia of F. tumidum and caged together with potted healthy gorse (ulex europaeus L.) at eight insects per plant. The insects deposited 310 conidia per plant on average but neither infection nor plant growth effects resulted. Only directly inoculated plants became infected and were significantly shorter with 42% reduction in fresh shoot weight compared with the control treatment. Epiphyas postvittana on its own did not cause any significant plant damage and did not enhance F. tumidum infection. The insect did not spread the conidia from diseased to healthy plants. The results showed that insects are unlikely to be effective vectors in a 'lure-load-infect' approach for biological control of gorse using F. tumidum.