Australasian Plant Disease Notes最新文献

In an attempt to provide additional information on the virome in apples in Southern Brazil in face of recurrent events of tree decline, plant samples of regional apple orchards have been submitted to HTS (high-throughput sequencing) analysis. Besides common latent viruses, results showed additionally the presence of apple rubbery wood virus 2 (ARWV 2) and citrus concave gum-associated virus (CCGaV) in orchards with decline history.

This is the first report of yambean mosaic virus and lettuce chlorosis virus in Australia. Both viruses were initially identified co-infecting the Fabaceae weed, Calopogonium mucunoides collected from Umagico in far north Queensland. Full coding sequences of both viruses were obtained with high throughput sequencing and confirmed with RT-PCR and Sanger sequencing. Lettuce chlorosis virus has subsequently been confirmed in several other species collected from far north Queensland and may become a new emerging threat to agronomical crops in Australia.

Hop cyst nematode, Heterodera humuli Filipjev, 1934 was found in soil samples collected from hop farms in Bushy Park, Tasmania and in Merriang, Victoria, Australia. Morphological and molecular characteristics were consistent with those described for this species in other parts of the world. Novel gene sequences of ITS rRNA, 28S rRNA and CO1 mtDNA generated from cysts were compared against sequences of H. humuli available on the NCBI GenBank database, demonstrating little to no genetic variation between Australian hop cyst nematode populations and those from other regions. This report provides the first molecular sequence data for H. humuli from Australia and reports a significant range extension of this cyst nematode from Tasmania to the Australian mainland.

Passion fruit (Passiflora edulis) is one of the tropical fruits well-adapted to Florida’s hot and humid climate. A high population of root-knot nematode, Meloidogyne incognita was identified morphologically from soil samples taken from declined passion fruit vines in an organic field in North Florida. Species identification was also confirmed based on DNA-based diagnostics using species-specific primers and sequencing based on D2-D3 of 28 S and ITS of ribosomal DNA. To the best of our knowledge, this is the first report of infection of purple passion fruit with M. incognita in Florida, USA.

Litsea deccanensis is a commercially important tree, distributed in South India and Sri Lanka. The seedlings raised in the nursery were found infected and wilted. The disease incidence rate was recorded nearly 40%. The fungus was isolated from the disease sample and grown on PDA. The same fungus was re-isolated and identified from diseased stems after the pathogenicity test, which showed the pathogenic behaviour of the isolated fungus, thus fulfilling Koch's postulates. Based on cultural and morphological characteristics followed by molecular analyses (ITS and TEF1), the pathogen was identified as Clonostachys byssicola (Bionectriaceae). This communication is the first report of C. byssicola causing seedling wilt in L. deccanensis from the Southern Western Ghats, Kerala, India.

Paramyrothecium foliicola is reported for the first time in Brazil and worldwide causing leaf spots on hop (Humulus lupulus). The fungus was identified with a combination of morphological and molecular information. The pathogenicity of P. foliicola to hop was demonstrated through inoculations under controlled conditions. 

White mold of cabbage caused by Sclerotinia sclerotiorum was identified in Bangladesh Agricultural Research Institute (BARI), Bangladesh. The fungus was isolated from the symptomatic leaves of cabbage on potato dextrose agar (PDA) medium. Subsequent inoculation of S. sclerotiorum on detached cabbage leaves and cabbage heads confirmed the pathogenicity of fungus. Based on morphological characteristics and phylogenetic analysis, the pathogen was identified as Sclerotinia sclerotiorum.

A morphometrics, morphological and molecular study revealed the presence of the stunt nematode Tylenchorhynchus annulatus in rhizosphere soil of paddy rice and corn in Central Java, Indonesia. Phylogenetic analysis placed the Indonesian populations in a clade with populations from China and South Korea, separated from populations from the USA. To our knowledge this is the first report of T. annulatus in Indonesia.

A powdery mildew has been observed for several years on Rosa canina plants in Idaho and Utah, USA. Morphology showed it was in the genus Podosphaera and sequencing of the internal transcribed spacer (ITS) region indicated Podosphaera pannosa. This is the first confirmed (i.e., evidence-supported) report of P. pannosa occurring on Rosa canina in North America.

Little leaf and yellowing symptoms associated with phytoplasma disease were observed in Pyracantha angustifolia in Turkey. Amplification (through nested PCR) and virtual restriction fragment length polymorphism (V-RFLP) confirmed the presence of phytoplasma in the symptomatic plants the phylogeny based on the R16F2n/R2 sequences of the P. angustifolia phytoplasma was established and the sequence analysis showed that the isolate had 98.7% similarity to ‘Candidatus Phytoplasma australasia’, a member of the 16SrII-D subgroup. This is the first world report of a phytoplasma in P. angustifolia and its first identification in the Republic of Türkiye.