Australasian Plant Disease Notes最新文献

In a survey in 2020, Salix babylonica trees displaying symptoms of phyllody, little leaves, and dieback were observed in Xinjiang province of China. Nested PCRs carried out using universal primer pairs for 16 S rRNA and tuf genes, detected the presence of phytoplasmas in symptomatic trees, while no amplification was found in symptomless trees. Blastn and phylogenetic analyses showed that detected phytoplasmas belong to the species ‘Candidatus Phytoplasma ziziphi’, ribosomal subgroup 16SrV-B. This is the first report of S. babylonica as plant host of ‘Ca. Phytoplasma ziziphi’, associated with phyllody disease in China.

Diseases caused by Fusarium species in garlic, which is among the products of economic importance, cause serious yield losses. While the isolation and characterization of Fusarium species has mostly been done from cloves and storage, the disease agent has been documented in very few seedling stages. In our study, eight isolates were obtained from specimens at the seedling stage, and species were defined according to morphological and molecular characterizations. Two isolates were identified as F. oxysporum, and the other six as F. proliferatum. As a result of cross pathogenicity of F. oxysporum isolates with onions, these isolates were defined as F. oxysporum f. sp. garlic. According to the data obtained from our study, these species that cause basal rot in garlic from Turkey were characterized for the first time using molecular techniques. In addition, this publication Fusarium oxysporum f.sp. garlic is the first report from Turkey.

Banana bunchy top virus is reported for the first time in Laos. Infected plants showed typical disease symptoms and the two complete genome sequences reported place the isolates in the Southeast Asian subgroup.

Occurrence of cyst nematode Heterodera daverti Wouts and Sturhan 1978 (Wouts & Sturhan 1978) is reported from Australia for the first time. Cysts were recovered from soil samples collected from a hop farm in Merriang, Victoria. Morphological and morphometric characteristics of cysts and second stage juveniles match those described for this species reported from other parts of the world. Identification was further supported by molecular evidence through comparison of newly generated sequences of ITS rRNA, CO1 mtDNA and 28S rRNA gene regions with sequences previously available on NCBI GenBank.

This is the first report of cactus virus X in Spain. It was found in dragon fruit (Hylocereus undatus) plants growing in an orchard, that showed mild chlorotic symptoms. The virus was identified following RT-PCR and Sanger sequencing of total RNA-extractions of symptomatic tissue. This also the first report of this virus in dragon fruits in Europe, and propagation of this emerging crop through planting of cuttings should include testing for this virus in order to prevent further spread.

In March 2021, severe signs of powdery mildew were observed on leaves and stems of Coccinia grandis in the Manchar, Pune District, Maharashtra state, India. Based on morphological examination, phylogenetic analyses, and pathogenicity test, the causal agent of powdery mildew on Coccinia grandis was identified as Golovinomyces tabaci. To our knowledge, this is the first record of G. tabaci infecting C. grandis in India. Previously, G. tabaci had only been reported on C. grandis from Taiwan and Thailand.

Clover yellow mosaic virus (ClYMV) is reported for the first time in two cultivars of ornamental verbena (Verbena X hybrid) from Christchurch in New Zealand. Sequencing of a ~ 500 bp fragment of the 8 KDa triple gene block and coat protein partial genes indicated the NZ isolates were closely related to ClYMV from verbena in the UK and Poland and more distantly to isolates from clover in Australia and Japan. ClYMV has been intercepted in quarantine in tulips and detected in white clover in Auckland; the verbena isolates may represent a separate incursion into NZ.

Austropuccinia psidii, the fungus causing myrtle rust, was detected in Western Australia for the first time in June 2022. Few Western Australian plant species have been screened for response to the pathogen. Melaleuca thyoides, Melaleuca marginata and Melaleuca leucadendra grown from seeds sourced from Western Australian populations were all highly susceptible to an isolate of the pathogen from eastern Australia.