Abstract
Hydrangea anomala subsp. petiolaris (synonym H. petiolaris and H. scandens), also known as climbing hydrangea, is cultivated as an ornamental for landscaping in parks and gardens. This species, belonging to the Hydrangeaceae and native to the woodlands of Japan and coastal China, is widely appreciated for its abundant, creamy white flowers with a sweet aroma, particularly in shade gardens. During the summer of 2006, extensive necroses were observed on leaves and young stems of 3-year-old plants grown outdoors in several gardens of Piedmont of northern Italy. In many cases, on the upper side of the leaves, necrotic spots (4 to 10 mm in diameter) turned progressively black. Lesions often coalesced, generating larger (2 to 6 cm in diameter) necrotic areas. Necroses initially developed mainly at leaf margins and near petioles, and severely affected plants were defoliated. Infected plants rarely died, but the presence of lesions reduced the aesthetic quality and subsequently the commercial value. The disease occurred on 50 of 100 plants. A fungus was consistently isolated from infected leaves on potato dextrose agar (PDA) and identified on the basis of its morphological characteristics as an Alternaria sp. Conidia were dark gray, multicellular, clavate to pear shaped, measuring 23 to 54 × 10 to 13 μm (average 38 × 12 μm), with five longitudinal crosswalls and a relatively short apical beak. DNA was extracted with a Nucleospin Plant Kit (Macherey Nagel, Brockville, ON, Canada) and PCR was carried out with ITS 6/ITS 4 primer (2). A 557-bp PCR product was sequenced, and a BLASTn search (1) confirmed that the sequence corresponded to Alternaria compacta (99% homology). The nucleotide sequence has been assigned GenBank Accession No. EU 128529. Pathogenicity tests were performed by spraying leaves of healthy 1-year-old potted H. anomala plants with an aqueous 10 5 CFU/ml spore suspension. The inoculum was obtained from cultures of the fungus grown on sterilized host leaves placed on PDA for 20 days in light/dark at 23 ± 1°C. Plants sprayed only with water served as controls. Five plants were used for each treatment. Plants were covered with plastic bags for 3 days after inoculation and maintained between 12 and 22°C. Lesions developed on leaves 8 days after inoculation with the spore suspension, whereas control plants remained healthy. A. compacta was consistently reisolated from these lesions. The pathogenicity test was repeated twice. The presence of an Alternaria sp. on H. macrophylla was reported in the United States (3), whereas A. hortensiae was observed in Spain on H. hortensis. Recently, A. alternata belonging to the alternata group was reported on H. macrophylla in Italy (4). This is, to our knowledge, the first report of A. compacta on H anomala subsp. petiolaris in Italy. References: (1) S. F. Altschud et al. Nucleic Acids Res. 25:3389, 1997. (2) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (3) M. L. Daughtrey et al. Page 9 in: Compendium of Flowering Potted Plant Diseases. American Phytopathological Society. St. Paul, MN, 1995. (4) A. Garibaldi et al. Plant Dis. 91:767, 2007.
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Claims 6
Claim · model-written summary
Necrotic leaf and stem lesions were observed in three-year-old hydrangeas in Piedmont.
- Taxon
- Hydrangea anomala subsp. petiolaris
Hydrangea petiolarist0 - Organ / stage
- leaves and young stemse0
- Outcome
- extensive necrosese0
- Setting
- Piedmont of northern Italye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“extensive necroses were observed on leaves and young stems of 3-year-old plants grown outdoors in several gardens of Piedmont of northern Italy”
t0“Hydrangea anomala subsp. petiolaris”
Claim · model-written summary
The disease affected 50 of 100 plants.
- Taxon
- Hydrangea anomala subsp. petiolarisHydrangea petiolarist0
- Outcome
- disease occurrede0
- Value
- 50 of 100 plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The disease occurred on 50 of 100 plants.”
t0“Hydrangea anomala subsp. petiolaris”
Claim · model-written summary
The isolated fungus was identified as Alternaria compacta by sequence comparison.
- Taxon
- Hydrangea anomala subsp. petiolarisHydrangea petiolarist0
- Interactor
- Alternaria compactaAlternaria compactae0pathogen
- Outcome
- sequence corresponded to Alternaria compactae0
- Value
- 99% homologye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“confirmed that the sequence corresponded to Alternaria compacta (99% homology)”
t0“Hydrangea anomala subsp. petiolaris”
Claim · model-written summary
Inoculated hydrangea leaves developed lesions after eight days, while water controls remained healthy.
- Taxon
- Hydrangea anomala subsp. petiolarisHydrangea petiolarist0
- Organ / stage
- leavese2
- Treatment
- spraying leaves of healthy 1-year-old potted H. anomala plants with an aqueous 10 5 CFU/ml spore suspensione0
- Interactor
- Alternaria compactaAlternaria compactat0pathogen
- Outcome
- Lesions developed on leavese2
- Qualifier
- 8 days after inoculatione2
- Comparator
- Plants sprayed only with watere1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pathogenicity tests were performed by spraying leaves of healthy 1-year-old potted H. anomala plants with an aqueous 10 5 CFU/ml spore suspension.”
e1“Plants sprayed only with water served as controls.”
e2“Lesions developed on leaves 8 days after inoculation with the spore suspension, whereas control plants remained healthy.”
t0“Alternaria compacta on Hydrangea anomala subsp. petiolaris”
Claim · model-written summary
Alternaria compacta was reisolated from inoculation lesions.
- Taxon
- Hydrangea anomala subsp. petiolarisHydrangea petiolarist0
- Interactor
- Alternaria compactaAlternaria compactat0pathogen
- Outcome
- A. compacta was consistently reisolated from these lesionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A. compacta was consistently reisolated from these lesions.”
t0“Alternaria compacta on Hydrangea anomala subsp. petiolaris”
Claim · model-written summary
The authors report the first occurrence of A. compacta on this hydrangea in Italy.
- Taxon
- Hydrangea anomala subsp. petiolarisHydrangea petiolarist0
- Interactor
- A. compactaAlternaria compactae0pathogen
- Outcome
- first report of A. compacta on H anomala subsp. petiolaris in Italye0
- Setting
- Italye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This is, to our knowledge, the first report of A. compacta on H anomala subsp. petiolaris in Italy.”
t0“Alternaria compacta on Hydrangea anomala subsp. petiolaris in Italy”