Source of Pseudocercospora macadamiae inoculum in macadamia trees and its use for characterising husk spot susceptibility in the field

Miles, A. K.; Akinsanmi, Olufemi A.; Aitken, E. A. B.; Drenth, A.

doi:10.1016/j.cropro.2010.06.021

Cited by 9 publications

(21 citation statements)

References 21 publications

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“…As the main source of P. macadamiae inoculum in the tree canopy (Miles et al 2010a), and as a measure of inoculum potential, a high incidence of sticktights in the tree canopy signifies the predisposition of host genotypes to increased husk spot disease intensity, thus, may serve as a functional phenotypic trait for disease resistance screening and cultivar evaluation programmes. This may provide a better and more costeffective disease management solution than physical removal of the infective host residues which is labourintensive and often considered not to be economical (Miles et al 2010a;Marin et al 2003).…”

Section: Discussionmentioning

confidence: 99%

“…The prevalence of sticktights was assessed using a rating scale based on the number and distribution of sticktights in the tree canopy: [0 = no sticktights, 1 = \5 sticktights, 2 = 5-10 sticktights, 3 = [10 sticktights and well distributed within canopy, 4 = few (\5) clusters of sticktights, and 5 = several ([5) clusters of sticktights and well distributed within canopy] (Miles et al 2010a). Prevalence data were collected twice a year at early season (OctoberNovember) and mid-season (March-April).…”

Section: Prevalence Of Sticktights In Tree Canopy As a Predictor Of Hmentioning

confidence: 99%

“…The pathogen perpetuates in the tree canopy on diseased husks that failed to abscise. These are termed 'sticktights' (Miles et al 2010a). Viable spores have been consistently obtained from diseased sticktights for over 30 months and the removal of sticktights from the tree canopy achieved a significant reduction in disease incidence (Miles et al 2010a).…”

Section: Introductionmentioning

confidence: 98%

“…These are termed 'sticktights' (Miles et al 2010a). Viable spores have been consistently obtained from diseased sticktights for over 30 months and the removal of sticktights from the tree canopy achieved a significant reduction in disease incidence (Miles et al 2010a). Infection of fruit occurs most readily when fruit is at approximately 3 mm diameter (Akinsanmi et al 2007;Miles et al 2010b).…”

Section: Introductionmentioning

confidence: 98%

“…This is heightened by the continual presence of sticktights in the tree canopy. The physical removal of sticktights or other infective host residues on a large-scale is generally a labourintensive task and often not economical in commercial crops (Miles et al 2010a;Marin et al 2003;Johnson and Stockwell 1998). A more cost-effective and sustainable solution would be to utilise cultivars that do not retain infective materials such as sticktights in the canopy.…”

Section: Introductionmentioning

confidence: 99%

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Pericarps retained in the tree canopy and stomatal abundance are components of resistance to husk spot caused by Pseudocercospora macadamiae in macadamia

2012

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Pseudocercospora macadamiae Beilharz, Mayers and Pascoe infects macadamia fruit via stomata causing husk spot disease. Information on the variability of fruit stomatal abundance, its association with diseased fruit pericarps (sticktights) that are retained in the tree canopy, and its influence on the husk spot intensity (incidence, severity and lesion number) among macadamia genotypes is lacking. We examined a total of 230 macadamia trees comprising 19 cultivars, 56 wild germplasm accessions and 40 breeding progeny, for the prevalence of sticktights and husk spot intensity over three production seasons. We observed a strong association between the prevalence of sticktights and disease intensity indicating its usefulness as a predictor of husk spot and as a useful phenotypic trait for husk spot resistance selection in breeding programmes. Similarly, stomatal abundance varied among macadamia genotypes, and a significant linear relationship (P \ 0.001; 93%) was observed between fruit stomatal abundance and husk spot for all the macadamia genotypes analysed, confirming the utility of that trait for disease resistance screening. The genotypes were grouped into disease resistance groups. Correlations between fruit stomatal abundance, disease intensity and prevalence of sticktights revealed that the numbers of sticktights, and relative stomatal abundance were the main factors influencing the intensity of husk spot among macadamia genotypes. This is the first comprehensive study of natural variation of stomatal abundance in Macadamia species that reveals genetic variation, and provides relevant relationships with disease intensity and the prevalence of sticktights. The phenotypic plant traits indentified in this study may serve as selection tools for disease resistance screening in macadamia breeding programmes.

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Section: Discussionmentioning

confidence: 99%

Section: Prevalence Of Sticktights In Tree Canopy As a Predictor Of Hmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Pericarps retained in the tree canopy and stomatal abundance are components of resistance to husk spot caused by Pseudocercospora macadamiae in macadamia

2012

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Characterization and development of qPCR for early detection and quantification of Pseudocercospora macadamiae at different stages of infection process

Ong

Akinsanmi

2016

Eur J Plant Pathol

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Biology and pathogenicity of fungi causing husk rot of macadamia in South Africa

Twiddy,

Fouché,

Akinsanmi

et al. 2024

Eur J Plant Pathol

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Fungal diseases of macadamia fruit in South Africa have the potential to cause notable economic damage in this rapidly growing industry. To improve our understanding of the species involved in husk rot in macadamia orchards, a survey was conducted over two consecutive growing seasons to identify Colletotrichum, Diaporthe and Calonectria spp. that are associated with husk rot-infected macadamia fruits, and to investigate the occurrence of these fungi in asymptomatic and symptomatic fruits at the four stages of fruit development. Of the 425 fungal isolates obtained from the survey, Colletotrichum and Diaporthe were the most frequently isolated genera confirming the important role that these causal agents play in the husk rot epidemics. The detection of Calonectria species was low, only from symptomatic fruits and limited to a few locations in the main macadamia-producing provinces in South Africa. Colletotrichum and Diaporthe species were detected throughout the season at different stages of fruit development and in both symptomatic and asymptomatic fruits. The study confirmed that three fungal pathogens cause husk rot of macadamia in South Africa, with Colletotrichum and Diaporthe species that may have a latent phase in macadamia fruit. Studies of the growth characteristics of the husk rot pathogens revealed varied optimal growth temperatures, which may influence their prevalence in the different provinces in South Africa where macadamia is grown. The significance of the varied prevalence and biology of the causal agents in husk rot epidemics are discussed, which may be helpful management strategies.

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Source of Pseudocercospora macadamiae inoculum in macadamia trees and its use for characterising husk spot susceptibility in the field

Cited by 9 publications

References 21 publications

Pericarps retained in the tree canopy and stomatal abundance are components of resistance to husk spot caused by Pseudocercospora macadamiae in macadamia

Pericarps retained in the tree canopy and stomatal abundance are components of resistance to husk spot caused by Pseudocercospora macadamiae in macadamia

Characterization and development of qPCR for early detection and quantification of Pseudocercospora macadamiae at different stages of infection process

Biology and pathogenicity of fungi causing husk rot of macadamia in South Africa

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