Australasian Plant Pathology最新文献

Early recognition of symptoms of infection is essential to prevent diseases from spreading through nurseries and into planted systems. In plantations, symptoms of Ceratocystis manginecans infection are typically wilt and canker but symptoms may differ at the nursery stage and as yet have not been described for Eucalyptus pellita. In this study, disease symptoms were recorded over a three-month period in an E. pellita nursery and isolates trapped. Then, to clearly identify those relating to ceratocystis disease and any related mortality, two C. manginecans isolates were re-inoculated by either spraying or dipping of healthy plantlets raised by tissue culture and mini-cuttings. Many disease symptoms were observed in the nursery but only perithecia on the leaves and stems was a clear indication of the presence of a Ceratocystis pathogen. Nine pathogenic fungal species, including C. manginecans, were isolated and identified by DNA analysis. Koch’s postulates indicated that leaf blight associated with C. manginecans was black-brown in colour, irregular, with uneven edges and surrounded by a yellow margin or halo on the upper leaf surface. Mortality following inoculation of plantlets by spraying immediately after planting was > 70%; by contrast, mortality of mini-cuttings was < 50% if spraying was done just before transplanting but < 20% if done 7 or 14 days after transplanting. Isolate EP313C caused significantly greater mortality than isolate EP106C. The research showed that C. manginecans and other pathogens were present in the nursery environment and must be identified and managed as part of good nursery practice.

In this study, two efficient plant growth promoters coupled with potent antagonists viz. Pseudomonas monteilii strain-CRC1, Cedecea davisae strain-CRC2 and AM Fungi named Glomus intraradices (GI) were assessed individually and in combination for their potential to increase yield and essential oil yield as well as lessen the severity of the disease caused by Rhizoctonia solani in Pogostemon cablin (patchouli). In field trials, nine treatments were used: CRC1, CRC2, GI, CRC1 + CRC2, CRC1 + GI, CRC2 + GI, CRC1 + CRC2 + GI, un-inoculated vermicompost, and uninoculated soil as control, with five replications in randomised complete block design, where Rhizoctonia root-rot/wilt was a persistent problem. As compared to the control, the plants inoculated with CRC1 + CRC2 + GI performed best and significantly increased the plant height (87%), plant spread (50%), branch count (67%), herbs yield (67%), essential oil yield (69%) as well as reduced the percent disease index (68%) and percent wilt incidence (87.5%). Moreover, the Patchouli alcohol, a key component of its essential oil, was found to be markedly enhanced by 10% in CRC1 + CRC2 + GI inoculated plants. Furthermore, 43, 27 and 191% of higher uptake of NPK were observed in CRC1 + CRC2 + GI inoculated plants, respectively. After harvesting, a considerable abundance of CRC1, CRC2, and GI in the rhizosphere soil was observed. The results of this experiment indicate that higher herb yields and other observed plant attributes could be due to improved nutrient (NPK) uptake by the patchouli plants. The management of wilt disease and the production of high-quality essential oils in patchouli both can be accomplished with the help of the established consortium.

Cacao (Theobroma cacao) is a tropical plant that is grown throughout India. Cacao pods exhibiting chocolate brown patched symptoms were collected. The organism was isolated and cultured on V8 Agar from the diseased samples. The pathogenicity was proved on Cacao pods by inoculating mycelium of the organism and Koch’s postulates were proved by re-isolating the pathogen. The pathogen was identified as Phytophthora tropicalis based on cultural and morphological characters, followed by molecular investigations (ITS and COX1). This is the first report of Phytophthora tropicalis causing black pod of Cacao in India.

Badnaviruses infecting sugarcane, collectively called sugarcane bacilliform viruses (SCBVs), are reported worldwide and are responsible for causing leaf fleck disease in sugarcane. SCBVs are genetically heterogeneous members of the badnavirus species complex. The objective of this study was to evaluate the genetic diversity of sugarcane bacilliform viruses (SCBVs) in four distinct sugarcane growing sites in Ethiopia. Additionally, the study aimed to examine the transmission of SCBV through vectors. A total of 270 sugarcane leaf samples, including both virus-suspected (symptomatic) and asymptomatic leaves, were collected and tested using a PCR assay with SCBV-F and SCBV-R primer pairs. Out of these samples, 67 (24.8%) were found to be SCBV-positive. Phylogenetic analysis and pairwise sequence comparisons based on the partial RT-RNase H coding region showed that the SCBVs in Ethiopia are genetically diverse. The phylogenetic analysis revealed that isolates from the current study formed four clusters together with SCBV-G, L, Q and S isolates reported from different parts of the world. This suggests that the introduction of SCBV to Ethiopia may have occurred in multiple countries. The glasshouse experiments demonstrated the efficient transmission of SCBV from infected to healthy sugarcane plants by pink sugarcane mealybugs (Saccharicoccus sacchari), which are associated with the sugarcane crop in the field. These findings contribute to the current understanding of the genetic diversity of SCBVs in Ethiopia.

Wheat is among the top food crops and its production needs to be increased to tackle food security. In the developing world subsistence farmers are often unaware of resistant wheat varieties and cannot afford expensive fungicides. This study was designed to evaluate anti-fungal potential of biofabricated Zinc Oxide (ZnO) nanoparticles (NPs) to control leaf rust of wheat. Wheat variety Morocco was used because of its susceptibility to all known strains of Puccini triticina, the causal agent of wheat leaf rust. The green technology based ZnO NPs were prepared. Six treatments varying from 25 to 150 ppm of ZnO NPs concentrations were used. Treatments T4 to T7 provided a high level of protection against leaf rust. This technology will be useful for subsistence/organic farmers and will help them to avoid environmental pollution. The large-scale production of ZnO NPs is feasible and can lead to commercialization for broad-acre farmers.

Sorghum is the fifth most important cereal crop in the world. There is a high potential for sorghum production in Indonesia because of its drought tolerance and wide adaptability. Sorghum cultivation is constrained in Indonesia by pests and diseases. One such disease is tar-spot caused by the Phyllachora sp., an obligate fungal pathogen. Tar spot disease of sorghum has not been widely reported. This study reports the finding of Phyllachora species based on the morphology and molecular identification of tar spot on leaves of sorghum plants of Latu Monca and Latu Kaca local varieties.The pathogen was identified as Phyllachora species. This is the first report of tar spots of sorghum caused by Phyllachora in West Lombok Regency, West Nusa Tenggara Province, Indonesia.

Hormozgan province in the south of Iran is one of the main regions in producing tomatoes, eggplants, bell peppers, and other vegetables as well as sesame in the winter season. In a 2021–2022 survey for phytoplasmas in different areas of this province, phytoplasma–type symptoms were observed in tomato, bell pepper, eggplant and sesame crops and many weed plants including Chenopodium album, Taraxacum officinale, Erodium cicutarium, Physalis angulata, Convolvulus virgatus, Tephrosia apollinea, and Malva sylvestris. Nested PCR assays using primers P1/P7 followed by R16mF2/R16mR1 confirmed association of phytoplasma with all symptomatic plants. 16 S rRNA nucleotide sequencing followed by virtual RFLP analysis showed that all detected phytoplasma strains from different hosts and locations belonged to 16SrII-D subgroup, ‘Candidatus Phytoplasma australasia’. The latter seemed to be the dominant phytoplasma among herbaceous plants in the region. To our knowledge, this is the first world report of natural infection of T. officinale, E. cicutarium, P. angulata, C. virgatus, T. apollinea, and M. sylvestris by a 16SrII-D phytoplasma. These plants can act as alternative hosts for transmission of the phytoplasma strains to major agricultural plants including tomato, pepper, eggplant, sesame and probably other plants.

Coffee leaf rust (CLR) poses a significant threat to coffee crops worldwide, including those grown in Brazil. CLR thrives in climatic conditions ideal for coffee cultivation, which results in its constant presence in Brazilian coffee farms. The intensity of CLR exhibits variations as affected by interannual and spatial climate variability that shape epidemics. The aim of this study was to determine the agro-climatic favourability zones for CLR occurrence in the major coffee-producing regions of Brazil based on region-specific agro-climatic conditions. Climate data spanning from 1961 to 2015 at 46 sites were selected to represent the major coffee-producing regions. Using a CLR infection rate model, daily simulations were performed to calculate the cumulative infection rate (CIR) for each site and growing season, starting from 1^st October to 30^th June of the following year. Based on the CIR values, the sites and seasons were categorised into five favourability classes: Very Low, Low, Medium, High, and Very High. An Agro-Climatic Favourability index (ACFav_index) was developed, considering the frequency of seasons falling within each favourability class. A map displaying four distinct favourability zones across the studied regions was then obtained and showed that most of the traditional coffee-growing areas fell within the Medium to High Favourability zones for CLR. The obtained map, delineating CLR favourability zones, holds practical value for coffee growers, consultants, and policymakers alike. It can guide the selection of CLR-resistant coffee cultivars for new cultivation areas and aid in the development of effective disease control strategies.

Arecanut is an important commercial plantation crop in India, and many farm families depend solely on the arecanut industry. In July 2018, immature nuts were shed heavily due to fruit rot disease in the Western-Ghats region. Though the symptoms were suggestive of common fruit rot disease, they appeared to be unusual. The associated pathogen was isolated from the infected tissue using the standard isolation technique, and an oomycete fungus was consistently isolated from infected nuts. Based on the colony and spore morphology, the pathogen was identified as Phytophthora sp. and by multi-gene sequencing (ITS, β-tub, TEF-1α, and Cox-II) confirmed it as Phytophthora parsiana. The pathogenicity of the isolate (P25) was established by inoculating healthy arecanut fruits with the pin-prick method. To our knowledge, this is the pioneering work that represents the first report of Phytophthora parsiana infecting arecanut in Western-Ghats of Southern India.