Abstract
Citrus is one of the most important crops in Ghana, representing a large proportion of the fresh fruit consumed in the country. In 2004, symptoms consisting of necrotic leaf spots of about 1 cm in diameter with light brown centers and dark brown margins surrounded by a yellow halo were first observed in sweet orange (Citrus sinensis) and mandarin (C. reticulata) orchards in the Eastern Region of Ghana. Fruits with raised corky lesions of up to 3 to 4 cm in diameter with yellow halos were also observed. Affected fruit had longitudinal and transversal cracks in the rind with the internal locules exposed. Juice content in diseased fruit was strongly reduced, making them unsuitable for fresh consumption or processing. The disease expanded to the Central and Ashanti Regions, with incidences over 95% and estimated yield losses of about 50 to 90%. Symptomatic leaves and fruit collected in Kade in the Eastern Region were surface disinfested with 0.5% NaOCl for 5 min and small fragments from lesions were plated onto malt extract agar (MEA). Slow-growing fungal colonies were isolated from about 5% of the affected tissues plated after 5 days of incubation at 24 to 26°C, and were transferred to V-8 juice agar and MEA. Plates were incubated for 30 days at 24 to 26°C with 12 h of fluorescent light and 12 h of dark for morphological examination. Colonies were gray in the upper side and dark green on the underside. Conidia produced in culture were mostly solitary or in short chains of 2 to 6 spores, hyaline to pale brown, cylindrical, with rounded apex and base truncated. Conidia were 24 to 82 × 4 to 6 μm, with up to 3 to 5 transverse septa and no longisepta. The 5.8S, ITS2, and 28S ribosomal RNA (rRNA) regions were amplified using the primers ITS1 and ITS4 (3) and sequenced from DNA extracted from the isolate MC-39, obtained from sweet orange leaves in Kade (GenBank Accession No. KF111755). The sequence had 99% identity (total score 819, 85% coverage) with that of Pseudocercospora angolensis (T. Carvalho & O. Mendes) Crous & U. Braun epitype strain CBS 112933 (GU269836) (1). Pathogenicity tests were performed twice on 12-week-old detached fruit of sweet orange cv. Valencia Late of about 4 to 5 cm in diameter. Inoculations were performed using a conidial suspension (3.0 × 10 5 conidia/ml water) by spraying fruit to run off, brushing the rind, dipping for 6 min, or injecting 2 ml in the albedo. Twenty-two isolates were evaluated and 18 fruit were used for each inoculation technique, isolate and experiment. Fruit treated with sterile distilled water were used as controls. Inoculated fruit were maintained in humid chambers at 24 to 26°C. Disease incidence on inoculated fruit varied from 40.7% to 92.6% and severity from 2 to 3 to 3 to 11 lesions per fruit, depending on the isolate and inoculation technique. No symptoms were observed on control fruit. Fungal colonies morphologically identified as P. angolensis were reisolated from lesions on inoculated fruit, but not from asymptomatic control fruit. Based on these results, the disease was identified as Pseudocercospora fruit and leaf spot of citrus caused by P. angolensis. Until this present report, Ghana was considered one of the few countries in Central Africa that was still free of this citrus disease (2). References: (1) P. W. Crous et al. Stud. Mycol. 75:37, 2013. (2) A. A. Seif and R. J. Hillocks. Int. J. Pest Manag. 39:44, 1993. (3) T. J. White et al. Pages 315-322 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.
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Claims 11
Claim · model-written summary
Sweet orange and mandarin orchards had necrotic leaf spots in eastern Ghana.
- Taxon
- sweet orange (Citrus sinensis) and mandarin (C. reticulata)
Citrus sinensis.jpg?width=60)
Citrus reticulatae0 - Outcome
- necrotic leaf spotse0
- Value
- about 1 cme0
- Setting
- Eastern Region of Ghanae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“necrotic leaf spots of about 1 cm in diameter with light brown centers and dark brown margins surrounded by a yellow halo were first observed in sweet orange (Citrus sinensis) and mandarin (C. reticulata) orchards in the Eastern Region of Ghana”
Claim · model-written summary
Affected citrus fruit had raised corky lesions and rind cracks.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fruits with raised corky lesions of up to 3 to 4 cm in diameter with yellow halos were also observed. Affected fruit had longitudinal and transversal cracks in the rind with the internal locules exposed.”
t0“Citrus”
Claim · model-written summary
Juice content in diseased citrus fruit was strongly reduced.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Juice content in diseased fruit was strongly reduced”
t0“Citrus”
Claim · model-written summary
The citrus disease reached central and Ashanti regions with incidence over 95%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The disease expanded to the Central and Ashanti Regions, with incidences over 95% and estimated yield losses of about 50 to 90%.”
t0“Citrus”
Claim · model-written summary
Estimated citrus yield losses were about 50 to 90%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“estimated yield losses of about 50 to 90%”
t0“Citrus”
Claim · model-written summary
The isolate from sweet orange leaves had 99% sequence identity with the Pseudocercospora angolensis epitype.
- Taxon
- sweet orangeCitrus sinensise1
- Interactor
- Pseudocercospora angolensisPseudocercospora angolensise0pathogen
- Outcome
- sequencee0
- Value
- 99% identitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The sequence had 99% identity (total score 819, 85% coverage) with that of Pseudocercospora angolensis (T. Carvalho & O. Mendes) Crous & U. Braun epitype strain CBS 112933 (GU269836)”
e1“obtained from sweet orange leaves in Kade”
Claim · model-written summary
Inoculated sweet orange fruit developed disease with incidence from 40.7% to 92.6%.
- Taxon
- sweet orangeCitrus sinensise2
- Material
- Valencia Latee2
- Treatment
- inoculatede0
- Outcome
- Disease incidencee0
- Value
- 40.7% to 92.6%e0
- Qualifier
- depending on the isolate and inoculation techniquee0
- Comparator
- sterile distilled watere1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Disease incidence on inoculated fruit varied from 40.7% to 92.6% and severity from 2 to 3 to 3 to 11 lesions per fruit, depending on the isolate and inoculation technique.”
e1“Fruit treated with sterile distilled water were used as controls.”
e2“sweet orange cv. Valencia Late”
Claim · model-written summary
Inoculated sweet orange fruit developed 2 to 11 lesions per fruit, depending on isolate and technique.
- Taxon
- sweet orangeCitrus sinensise2
- Treatment
- inoculatede3
- Outcome
- severitye0
- Value
- 2 to 3 to 3 to 11 lesions per fruite0
- Comparator
- sterile distilled watere1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“severity from 2 to 3 to 3 to 11 lesions per fruit, depending on the isolate and inoculation technique”
e1“Fruit treated with sterile distilled water were used as controls.”
e2“sweet orange cv. Valencia Late”
e3“Disease incidence on inoculated fruit varied from 40.7% to 92.6% and severity from 2 to 3 to 3 to 11 lesions per fruit, depending on the isolate and inoculation technique.”
Claim · model-written summary
Control sweet orange fruit showed no symptoms.
- Taxon
- sweet orangeCitrus sinensise1
- Organ / stage
- fruite0
- Outcome
- No symptomse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No symptoms were observed on control fruit.”
e1“sweet orange cv. Valencia Late”
Claim · model-written summary
P. angolensis was reisolated from inoculated sweet orange lesions but not asymptomatic controls.
- Taxon
- sweet orangeCitrus sinensise1
- Interactor
- P. angolensisPseudocercospora angolensise0pathogen
- Outcome
- P. angolensis were reisolated from lesions on inoculated fruit, but not from asymptomatic control fruite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungal colonies morphologically identified as P. angolensis were reisolated from lesions on inoculated fruit, but not from asymptomatic control fruit.”
e1“sweet orange cv. Valencia Late”
Claim · model-written summary
The citrus disease in Ghana was identified as fruit and leaf spot caused by P. angolensis.
- Interactor
- P. angolensisPseudocercospora angolensise0pathogen
- Outcome
- Pseudocercospora fruit and leaf spot of citruse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the disease was identified as Pseudocercospora fruit and leaf spot of citrus caused by P. angolensis”
t0“Citrus”
The same questions in other papers
inoculation · disease · Citrus sinensis (sweet orange)Positive and negative results
9 papers in the same direction as this paper · 5 in the opposite direction
- positive
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See all 15 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.