Remote sensing approaches are often used to monitor land cover change. However, the small physica... more Remote sensing approaches are often used to monitor land cover change. However, the small physical size (about 1–2 hectare area) of smallholder orchards and the cultivation of cocoa (Theobroma cocoa L.) under shade trees make the use of many popular satellite sensors inefficient to distinguish cocoa orchards from forest areas. Nevertheless, high-resolution satellite imagery combined with novel signal extraction methods facilitates the differentiation of coconut palms (Cocos nucifera L.) from forests. Cocoa grows well under established coconut shade, and underplanting provides a viable opportunity to intensify production and meet demand and government targets. In this study, we combined grey-level co-occurrence matrix (GLCM) textural features and vegetation indices from Sentinel datasets to evaluate the sustainability of cocoa expansion given land suitability for agriculture and soil capability classes. Additionally, it sheds light on underexploited areas with agricultural potential....
Disease incidence and disease severity associated with Phytophthora palmivora and other fungi was... more Disease incidence and disease severity associated with Phytophthora palmivora and other fungi was greater in durian cv. Kho Qua Xanh fruits that had contact with soil during harvest, and when postharvest storage conditions were adjusted to 15 C and 90% ...
Ambrosia beetles have co-evolved symbiotic relationships with an array of fungal partners. Mutual... more Ambrosia beetles have co-evolved symbiotic relationships with an array of fungal partners. Mutualistic fungal partners are often highly successful in vertical transmission between beetle generations. These persisting relationships can alter beetle behaviour, resulting in the opportunity to occupy new ecological niches and to spread geographically. In Australia, ambrosia beetles are not currently considered a significant pest in commercial Pinus plantations, where the bark beetle Ips grandicollis is known as the primary invader of stressed trees. However, in 2019, ambrosia beetles Xyleborus perforans and X. bispinatus, co-occurring with I. grandicollis, were found to have colonised a large proportion of drought-stressed trees in commercial Pinus plantations in north-east New South Wales. In this study, X. perforans (the most prevalent of two Xyleborus spp.) was collected from infested dead and dying trees in two NSW Pinus plantations. Fungal isolates of suspected Pinus pathogens were...
Abstract Identifying and evaluating disease resistance depends on rapid, reliable and robust bioa... more Abstract Identifying and evaluating disease resistance depends on rapid, reliable and robust bioassays that can rapidly screen large numbers of cultivars and breeding progenies. We developed seedling, leaf and stem bioassays to screen durian germplasm from Thailand, ...
This chapter provides an overview of the key factors driving the epidemiology of Phytophthora on ... more This chapter provides an overview of the key factors driving the epidemiology of Phytophthora on tropical tree crops including the fundamental biology, relevant environmental factors and agronomic practices unique to these systems. The cocoa black pod disease (P. palmivora), Phytophthora in the tropics, disease cycle of Phytophthora in the tropics, disease management (hygiene, soils, host plants, chemical and biological control) are discussed.
Cocoa is a key crop for small-scale farmers in Sulawesi, Indonesia. Decline in cocoa yield and co... more Cocoa is a key crop for small-scale farmers in Sulawesi, Indonesia. Decline in cocoa yield and cocoa price fluctuation have negatively affected the income of small-scale farmers. An approach to address the sustainability of small-scale cocoa farming is to diversify the household income via cocoa-goat mixed farming. This study aimed to assess whether cocoa-goat mixed farming was a viable and profitable enterprise for small-scale farmers in West Sulawesi by using cost benefit analysis (CBA). Three CBA models were developed to compare profitability of an existing medium-scale cocoa-goat mixed farm located in West Sulawesi with hypothetical small-scale cocoa monoculture and cocoa-goat mixed farming. The CBAs were informed by an interview using structured questionnaire and literature search. The principal CBA assessment criterion was net present value (NPV) while benefit cost ratio (BCR) and internal rate of return (IRR) were supplementary. Sensitivity analysis measured the impact of cha...
Theobroma cacao, the source of chocolate, is affected by destructive diseases wherever it is grow... more Theobroma cacao, the source of chocolate, is affected by destructive diseases wherever it is grown. Some diseases are endemic; however, as cacao was disseminated from the Amazon rain forest to new cultivation sites it encountered new pathogens. Two well-established diseases cause the greatest losses: black pod rot, caused by several species of Phytophthora, and witches’ broom of cacao, caused by Moniliophthora perniciosa. Phytophthora megakarya causes the severest damage in the main cacao producing countries in West Africa, while P. palmivora causes significant losses globally. M. perniciosa is related to a sister basidiomycete species, M. roreri which causes frosty pod rot. These Moniliophthora species only occur in South and Central America, where they have significantly limited production since the beginnings of cacao cultivation. The basidiomycete Ceratobasidium theobromae causing vascular-streak dieback occurs only in South-East Asia and remains poorly understood. Cacao swollen...
We have identified phenological patterns of mature durian trees grown in the north of Queensland,... more We have identified phenological patterns of mature durian trees grown in the north of Queensland, Australia, and monitored the distribution of phosphonate following trunk injection at three distinct phenological periods, to identify the injection period which results in maximum uptake in all tree organs. Durian cultivars Gumpun, Parung and Gob Yaow were injected with 16 g a.i. phosphonate at each of three injection periods (early flowering fruit/fruit-set, mid-fruit-set, and immediately after harvest). In northern Queensland, durian shoot and root development appears to be active throughout the year despite the relatively cool conditions that occur during winter. Shoot-flushing activity often occurs in parts of the tree rather then uniformly over the canopy. Phosphonate was detected within two days of injection in all organs sampled and reached a peak between four and eight days after injection. The highest levels of phosphonate were recorded in leaves and flowers (mean value of 60 and 40 μg/g dry weight). Phosphonate levels either declined or increased with sampling date, depending on organ and injection time, but persisted in all tissues for at least 128 days. Phosphonate trunk injection trials were also carried out on local durian varieties in Vietnam. Under moderate disease pressure, annual injections of 16 g a.i. per tree gave superior control of canker compared with recommended sprays of metalaxyl or Aliette. Under high disease pressure, 48 g a.i., injected at 3 three-monthly intervals, gave the best disease control. Results presented in this paper demonstrate the efficacy of phosphonate in controlling phytophthora diseases in durian when applied as a trunk injection.
Remote sensing approaches are often used to monitor land cover change. However, the small physica... more Remote sensing approaches are often used to monitor land cover change. However, the small physical size (about 1–2 hectare area) of smallholder orchards and the cultivation of cocoa (Theobroma cocoa L.) under shade trees make the use of many popular satellite sensors inefficient to distinguish cocoa orchards from forest areas. Nevertheless, high-resolution satellite imagery combined with novel signal extraction methods facilitates the differentiation of coconut palms (Cocos nucifera L.) from forests. Cocoa grows well under established coconut shade, and underplanting provides a viable opportunity to intensify production and meet demand and government targets. In this study, we combined grey-level co-occurrence matrix (GLCM) textural features and vegetation indices from Sentinel datasets to evaluate the sustainability of cocoa expansion given land suitability for agriculture and soil capability classes. Additionally, it sheds light on underexploited areas with agricultural potential....
Disease incidence and disease severity associated with Phytophthora palmivora and other fungi was... more Disease incidence and disease severity associated with Phytophthora palmivora and other fungi was greater in durian cv. Kho Qua Xanh fruits that had contact with soil during harvest, and when postharvest storage conditions were adjusted to 15 C and 90% ...
Ambrosia beetles have co-evolved symbiotic relationships with an array of fungal partners. Mutual... more Ambrosia beetles have co-evolved symbiotic relationships with an array of fungal partners. Mutualistic fungal partners are often highly successful in vertical transmission between beetle generations. These persisting relationships can alter beetle behaviour, resulting in the opportunity to occupy new ecological niches and to spread geographically. In Australia, ambrosia beetles are not currently considered a significant pest in commercial Pinus plantations, where the bark beetle Ips grandicollis is known as the primary invader of stressed trees. However, in 2019, ambrosia beetles Xyleborus perforans and X. bispinatus, co-occurring with I. grandicollis, were found to have colonised a large proportion of drought-stressed trees in commercial Pinus plantations in north-east New South Wales. In this study, X. perforans (the most prevalent of two Xyleborus spp.) was collected from infested dead and dying trees in two NSW Pinus plantations. Fungal isolates of suspected Pinus pathogens were...
Abstract Identifying and evaluating disease resistance depends on rapid, reliable and robust bioa... more Abstract Identifying and evaluating disease resistance depends on rapid, reliable and robust bioassays that can rapidly screen large numbers of cultivars and breeding progenies. We developed seedling, leaf and stem bioassays to screen durian germplasm from Thailand, ...
This chapter provides an overview of the key factors driving the epidemiology of Phytophthora on ... more This chapter provides an overview of the key factors driving the epidemiology of Phytophthora on tropical tree crops including the fundamental biology, relevant environmental factors and agronomic practices unique to these systems. The cocoa black pod disease (P. palmivora), Phytophthora in the tropics, disease cycle of Phytophthora in the tropics, disease management (hygiene, soils, host plants, chemical and biological control) are discussed.
Cocoa is a key crop for small-scale farmers in Sulawesi, Indonesia. Decline in cocoa yield and co... more Cocoa is a key crop for small-scale farmers in Sulawesi, Indonesia. Decline in cocoa yield and cocoa price fluctuation have negatively affected the income of small-scale farmers. An approach to address the sustainability of small-scale cocoa farming is to diversify the household income via cocoa-goat mixed farming. This study aimed to assess whether cocoa-goat mixed farming was a viable and profitable enterprise for small-scale farmers in West Sulawesi by using cost benefit analysis (CBA). Three CBA models were developed to compare profitability of an existing medium-scale cocoa-goat mixed farm located in West Sulawesi with hypothetical small-scale cocoa monoculture and cocoa-goat mixed farming. The CBAs were informed by an interview using structured questionnaire and literature search. The principal CBA assessment criterion was net present value (NPV) while benefit cost ratio (BCR) and internal rate of return (IRR) were supplementary. Sensitivity analysis measured the impact of cha...
Theobroma cacao, the source of chocolate, is affected by destructive diseases wherever it is grow... more Theobroma cacao, the source of chocolate, is affected by destructive diseases wherever it is grown. Some diseases are endemic; however, as cacao was disseminated from the Amazon rain forest to new cultivation sites it encountered new pathogens. Two well-established diseases cause the greatest losses: black pod rot, caused by several species of Phytophthora, and witches’ broom of cacao, caused by Moniliophthora perniciosa. Phytophthora megakarya causes the severest damage in the main cacao producing countries in West Africa, while P. palmivora causes significant losses globally. M. perniciosa is related to a sister basidiomycete species, M. roreri which causes frosty pod rot. These Moniliophthora species only occur in South and Central America, where they have significantly limited production since the beginnings of cacao cultivation. The basidiomycete Ceratobasidium theobromae causing vascular-streak dieback occurs only in South-East Asia and remains poorly understood. Cacao swollen...
We have identified phenological patterns of mature durian trees grown in the north of Queensland,... more We have identified phenological patterns of mature durian trees grown in the north of Queensland, Australia, and monitored the distribution of phosphonate following trunk injection at three distinct phenological periods, to identify the injection period which results in maximum uptake in all tree organs. Durian cultivars Gumpun, Parung and Gob Yaow were injected with 16 g a.i. phosphonate at each of three injection periods (early flowering fruit/fruit-set, mid-fruit-set, and immediately after harvest). In northern Queensland, durian shoot and root development appears to be active throughout the year despite the relatively cool conditions that occur during winter. Shoot-flushing activity often occurs in parts of the tree rather then uniformly over the canopy. Phosphonate was detected within two days of injection in all organs sampled and reached a peak between four and eight days after injection. The highest levels of phosphonate were recorded in leaves and flowers (mean value of 60 and 40 μg/g dry weight). Phosphonate levels either declined or increased with sampling date, depending on organ and injection time, but persisted in all tissues for at least 128 days. Phosphonate trunk injection trials were also carried out on local durian varieties in Vietnam. Under moderate disease pressure, annual injections of 16 g a.i. per tree gave superior control of canker compared with recommended sprays of metalaxyl or Aliette. Under high disease pressure, 48 g a.i., injected at 3 three-monthly intervals, gave the best disease control. Results presented in this paper demonstrate the efficacy of phosphonate in controlling phytophthora diseases in durian when applied as a trunk injection.
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