Splash dispersal of Phyllosticta citricarpa conidia from infected citrus fruit

Perryman, S. A. M.; Clark, S. J.; West, Jonathan

doi:10.1038/srep06568

Cited by 38 publications

(30 citation statements)

References 24 publications

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“…These infections, which also occur under nets because of their permeability, cause scab, a disease that generates dark spots on the fruit and reduces its commercial value 8 . Wind speed has an impact on drying time and propagation of infection 9 and a large mesh size for exclusion nets is preferred to allow wind to pass through easily.…”

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confidence: 99%

Photo Initiated Chemical Vapour Deposition To Increase Polymer Hydrophobicity

Bérard

Patience

Chouinard

et al. 2016

Sci Rep

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Apple growers face new challenges to produce organic apples and now many cover orchards with high-density polyethylene (HDPE) nets to exclude insects, rather than spraying insecticides. However, rainwater- associated wetness favours the development of apple scabs, Venturia inaequalis, whose lesions accumulate on the leaves and fruit causing unsightly spots. Treating the nets with a superhydrophobic coating should reduce the amount of water that passes through the net. Here we treat HDPE and polyethylene terephthalate using photo-initiated chemical vapour deposition (PICVD). We placed polymer samples in a quartz tube and passed a mixture of H2 and CO through it while a UVC lamp (254 nm) illuminated the surface. After the treatment, the contact angle between water droplets and the surface increased by an average of 20°. The contact angle of samples placed 70 cm from the entrance of the tube was higher than those at 45 cm and 20 cm. The PICVD-treated HDPE achieved a contact angle of 124°. Nets spray coated with a solvent-based commercial product achieved 180° but water ingress was, surprisingly, higher than that for nets with a lower contact angle.

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confidence: 99%

Photo Initiated Chemical Vapour Deposition To Increase Polymer Hydrophobicity

Bérard

Patience

Chouinard

et al. 2016

Sci Rep

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“…and reduced viability compared to the ascospore, however, recent work suggest that water and wind may disperse conidia over longer distances than previously reported 16 .…”

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confidence: 55%

“…The increase in severity on fruit on the swale side of the tree to equal that of the road side of the tree may indicate disease progression from road to swale and indicate the direction from which the inoculum spread. Indeed, it has been shown that wind driven splash droplets can propel conidia upwards and outwards from the point of origin and this distance increases under the influence of wind 16 . Clearly the ascospore is not required for the spread of the disease into the topmost sections of the canopy (>3 m).…”

Section: Discussionmentioning

confidence: 99%

The Effect of Weather and Location of Fruit within the Tree on the Incidence and Severity of Citrus Black Spot on Fruit

Hendricks¹,

Christman²,

Roberts³

2020

Sci Rep

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Citrus black spot (CBS) caused by the fungus Phyllosticta citricarpa occurs in tropical and subtropical citrus production regions and affects all varieties of citrus. In Florida, the disease cycle is unique, having only the asexual spore. This work examines incidence and severity of CBS (hard spot symptoms) on fruit in two citrus groves during 2013-2014, 2014-2015 (Grove III) and 2015-2016 (Grove II) citrus seasons. Disease incidence and severity on fruit were analyzed based on citrus season, side of tree evaluated, height within the canopy, tree health, and tree age. Results indicate an increase in CBS incidence in Grove III between 2013-2014 and 2014-2015 seasons, with more infected or symptomatic fruit on the road side of the canopy and a higher incidence above 2 meters. Tree health status affected incidence but not severity and tree age had a significant effect on severity of CBS in Grove II. Analysis of weather data conducive for infection, between 2010 and 2017, indicated an average of 172 days per year (range: 104-261 days) when the temperature (15-35 °C) and relative humidity (RH ≥ 90% for 8 consecutive hours) were conducive for infection of fruit and an average of 98 days per year (range: 72-123 days) when the fruit were susceptible to infection. Citrus black spot caused by the fungus Phyllosticta citricarpa was first discovered on sweet orange in southwest Florida in April 2010 1. The disease has a worldwide distribution affecting all varieties of citrus within tropical and subtropical citrus production regions, particularly in warm, humid climates. The disease has been reported in Australia, South Africa 2 , and Argentina 3,4 since the early 1900's. It has more recently been introduced into Brazil, Cuba 5 , Uganda 6 , Ghana 7 , Italy, Malta, and Portugal 8. The fungus invades and colonizes the fruit rind producing five distinct lesion types 9,10. Lesions do not affect the internal quality of the fruit 10 , however in markets where fruit is quarantined it is precluded from sale in the fresh market, as opposed to endemic areas where less blemished fruit are sold. Fruit symptoms include hard spots (also known as shot hole spots), freckle spots, virulent spots, and false melanoses (see Supplementary Fig. S1). Interaction with spider mites produces cracked spots which have been observed in Brazil 11 and Florida 1. Yield losses due to premature fruit drop occurs under severe infections 7. Florida's citrus affected by this pathogen are placed under quarantine by the United States Department of Agriculture, restricting interstate movement of citrus materials. This places an additional economic cost due to the implementation of further phytosanitary practices in order to treat and move material within and outside of the state and country. Since the initial find in 2010, the quarantine zone has been extended to encompass 1160.32 km 2 (286,720 acres) within Lee, Charlotte, Collier, Hendry and Polk counties as of July 2019 12. The life cycle of P. citricarpa consists of a sexual (ascospores) and asexual (conidia) ...

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“…Spores were suspended in 2 mL of sodium chloride aqueous solution (NaCl, 0.85 w/v) and removed from sporulating colonies with a sterile pipette. Suspensions were adjusted to 10 6 conidia/mL (similar to Perryman et al, 2014)).…”

Section: Fungal Inoculation Assaysmentioning

confidence: 99%

Engineering d‐limonene synthase down‐regulation in orange fruit induces resistance against the fungus Phyllosticta citricarpa through enhanced accumulation of monoterpene alcohols and activation of defence

Rodríguez

Kava

Latorre-García

et al. 2018

Molecular Plant Pathology

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Terpene volatiles play an important role in the interactions between specialized pathogens and fruits. Citrus black spot (CBS), caused by the fungus Phyllosticta citricarpa, is associated with crop losses in different citrus-growing areas worldwide. The pathogen may infect the fruit for 20-24 weeks after petal fall, but the typical hard spot symptoms appear when the fruit have almost reached maturity, caused by fungal colonization and the induction of cell lysis around essential oil cavities. d-Limonene represents approximately 95% of the total oil gland content in mature orange fruit. Herein, we investigated whether orange fruit with reduced d-limonene content in peel oil glands via an antisense (AS) approach may affect fruit interaction with P. citricarpa relative to empty vector (EV) controls. AS fruit showed enhanced resistance to the fungus relative to EV fruit. Because of the reduced d-limonene content, an over-accumulation of linalool and other monoterpene alcohols was found in AS relative to EV fruit. A global gene expression analysis at 2 h and 8 days after inoculation with P. citricarpa revealed the activation of defence responses in AS fruit via the up-regulation of different pathogenesis-related (PR) protein genes, probably as a result of enhanced constitutive accumulation of linalool and other alcohols. When assayed in vitro and in vivo, monoterpene alcohols at the concentrations present in AS fruit showed strong antifungal activity. We show here that terpene engineering in fruit peels could be a promising method for the development of new strategies to obtain resistance to fruit diseases.

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Splash dispersal of Phyllosticta citricarpa conidia from infected citrus fruit

Cited by 38 publications

References 24 publications

Photo Initiated Chemical Vapour Deposition To Increase Polymer Hydrophobicity

Photo Initiated Chemical Vapour Deposition To Increase Polymer Hydrophobicity

The Effect of Weather and Location of Fruit within the Tree on the Incidence and Severity of Citrus Black Spot on Fruit

Engineering d‐limonene synthase down‐regulation in orange fruit induces resistance against the fungus Phyllosticta citricarpa through enhanced accumulation of monoterpene alcohols and activation of defence

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